eng 470 honours thesis: water system design for ......water system design for wadjemup conservation...

Water system design for Wadjemup Conservation Centre expansion on Rottnest Island Aled Lewis 2016

ENG 470 Honours Thesis:

Water system design for Wadjemup Conservation

Centre expansion on Rottnest Island

Aled Lewis

Semester 2, 2016


I

Executive Summary Continuing with the development of Rottnest Island’s infrastructure, the existing nursery is

under examination for its expansion. Taking on the goals of the Rottnest Island Authority,

the aim of the expansion will be to have the buildings off the grid for water and electricity as

well as providing accommodation for researchers, workspace for the island's

horticulturalists and volunteers, as well as being an educational building for the island's

visitors focusing on environmental issues.

This project tackles the water aspect of the development. This was conducted through

measuring the current water use and extrapolating this data to find the projected use at the

future site. From this a review of options was conducted to find what could be used at the

site to ensure water availability and treatment. The considered options have been split into

3 categories: input, which compared desalination and combination of rainwater and

desalination; On-site use, which compared the use of composting toilets and rainwater

flushed toilets and also the inclusion of a greywater system; Effluent treatment models,

which compared existing models and assessed their appropriateness for the Rottnest

system. The models reviewed are Findhorn’s “Living machine”, Currumbin’s textile filters,

Capo Di Monte’s membrane bioreactor and Council House 2’s ultra-filtration system.

The 48 possible combinations were condensed down to 14 systems due to constraints

present with certain components. These final 14 options were compared against each other

in a MCA table weighted with concerns from stakeholders on the criteria. This concluded in

the decision of having a system comprising of a combined rainwater harvesting and

desalination water source as the input, reclaimed water-flushed toilet system with the

Currumbin model textile filter as the effluent treatment method. Pricing this method gave a

20 year payback period for the system, as the lifespan of the majority of the components

was also 20 years, this system provided no financial benefits making this project break-even.


II

Acknowledgements

I would like to thank all those who helped me through this work by support or aiding my research.

The members of the Rottnest Island Authority for allowing me to work with them for this project,

notably, Shane Kearney, Tyra Garacci and Luke Wheat.

Thanks go to Martin Anda for his assistance and guidance through my years at Murdoch University.


III

Abbreviations

AGWR Australian guidelines for water recycling AWA Australian Water Association BOD Biological Oxygen Demand CDM Capo Di Monte CH2 Council House 2 DOH Department of Health DOW Department of Water EPA Environmental Protection Authority GTS Greywater Treatment System MCA Multi-Criteria Analysis NGI Nursery and gardening industry NSW New South Wales OPL One Planet Living RIA Rottnest Island Authority RO Reverse Osmosis RWH & RWHS Rain Water Harvesting and Rain Water Harvesting System SSF Slow Sand Filtration UV Ultra Violet WA Western Australia WELS Water Efficiency Labelling and Standard


IV

Table of Contents Executive Summary .................................................................................................................................. I

Acknowledgements ................................................................................................................................. II

Abbreviations ......................................................................................................................................... III

1. Introduction and Background ............................................................................................................. 1

1.1 Rottnest Island (Wadjemup) ......................................................................................................... 1

1.2 Water on Rottnest ......................................................................................................................... 2

1.3 One planet living and Earthcheck ................................................................................................. 4

1.4 Objectives ...................................................................................................................................... 5

2. Literature Review ................................................................................................................................ 6

2.1 Rainwater ...................................................................................................................................... 6

2.2 Desalination .................................................................................................................................. 7

2.3 Greywater ..................................................................................................................................... 7

2.4 Toilets ............................................................................................................................................ 8

2.5 Effluent treatment......................................................................................................................... 9

2.6 Legislation ................................................................................................................................... 10

2.7 Water reuse at nurseries ............................................................................................................. 10

2.8 Similar cases ................................................................................................................................ 11

3. Methods used to find water use ....................................................................................................... 13

3.1 Current water use........................................................................................................................ 13

3.2 Water audit ................................................................................................................................. 13

3.2.1 Overnight stay water use ..................................................................................................... 14

3.2.2 Day visit water use ............................................................................................................... 15

3.2.3 Confidence of calculated data compared to industry data ................................................. 16

4. Options considered for nursery system ............................................................................................ 17

4.1 Water sources ............................................................................................................................. 17

4.1.1 Rainwater ............................................................................................................................. 17

4.1.2 Water reuse: Greywater and Drainage capture .................................................................. 18

4.1.3 Saltwater desalination ......................................................................................................... 19

4.2 Toilets .......................................................................................................................................... 20

4.2.1 Rainwater and greywater flushed systems .......................................................................... 20

4.2.2 Composting toilets ............................................................................................................... 21

4.3 Effluent ........................................................................................................................................ 21

4.3.1 ‘Living machine’: Findhorn ................................................................................................... 21


V

4.3.2 Currumbin textile filters ....................................................................................................... 23

4.3.3 Capo di Monte Membrane bioreactor ................................................................................. 25

4.3.4 Council House 2, Multi water reuse ..................................................................................... 26

4.5 Flow options ................................................................................................................................ 27

5. Multi-Criteria Analysis ....................................................................................................................... 30

5.1 Cost ............................................................................................................................................. 30

5.2 Footprint...................................................................................................................................... 31

5.3 Complexity ................................................................................................................................... 32

5.4 Education potential ..................................................................................................................... 33

5.5 Environmental Factors ................................................................................................................ 34

5.6 Public perception ......................................................................................................................... 35

5.7 Availability of water .................................................................................................................... 36

5.8 Water quality .............................................................................................................................. 36

5.9 Life expectancy ............................................................................................................................ 37

5.10 Aesthetics .................................................................................................................................. 38

5.11 MCA summary ........................................................................................................................... 39

6. Results ............................................................................................................................................... 41

6.1 Sensitivity analysis ...................................................................................................................... 41

6.2 Final design ................................................................................................................................. 44

6.3 Guidelines & legislation ............................................................................................................... 45

6.4 Final cost & grants ...................................................................................................................... 46

7. Conclusion ......................................................................................................................................... 47

8. References ........................................................................................................................................ 49

9. Appendix ........................................................................................................................................... 56

9.1 Case studies ................................................................................................................................. 56

9.1.1 Ocracoke, USA ...................................................................................................................... 56

9.1.2 The Grove, Peppermint Grove ............................................................................................. 56

9.2 Desalination options ................................................................................................................... 57

9.3 Contact with companies regarding waterless toilets .................................................................. 59

9.3.1 Ecoflo.................................................................................................................................... 59

9.3.2 Dynamic supplies ................................................................................................................. 59

9.3.3 Waterwally ........................................................................................................................... 59

9.4 Complete list of combinations for water system......................................................................... 60

9.5 Contact with Orenco ................................................................................................................... 62


VI

9.6 Results from questionnaire ......................................................................................................... 65

9.7 Maintenance, monitoring and approvals ................................................................................... 65

9.7.1 Rainwater ............................................................................................................................. 65

9.7.3 Monitoring ........................................................................................................................... 69

9.8 Matlab model .............................................................................................................................. 69

List of Tables Table 1. Water charges at Rottnest Island .............................................................................................. 3

Table 2. Flow rates of appliances found on site at nursery .................................................................. 14

Table 3. Calculation of water use per person for overnight stay .......................................................... 15

Table 4. Calculation for water use for day visitors ............................................................................... 16

Table 5. Calculation of total daily and yearly use from two sources .................................................... 16

Table 6. Approved uses of greywater for commercial premises (Department of Health, 2010) ......... 18

Table 7. WELS rating for appliance water use ...................................................................................... 20

Table 8. Final water quality parameters for Findhorn water treatment method................................. 22

Table 9. Final water quality parameters for Currumbin water treatment method (Innoflow, 2009) .. 24

Table 10. Final water quality parameters for CDM water treatment method ..................................... 26

Table 11. Final water quality parameters for CH2 water treatment method ...................................... 27

Table 12. Final 14 combination options for MCA ................................................................................. 29

Table 13. Comparison of options for cost criterion .............................................................................. 31

Table 14. Information about UF filters available from Enviroconcepts (Enviroconcepts) .................... 32

Table 15. Information on RO filters available from Enviroconcepts (Enviroconcepts 1) ...................... 32

Table 16. Comparison of options for footprint criterion ...................................................................... 32

Table 17. Comparison of options for complexity criterion ................................................................... 33

Table 18. Comparison of options for education criterion..................................................................... 34

Table 19. Comparison of options for environment criterion ................................................................ 35

Table 20. Comparison of options for public perception criterion ........................................................ 36

Table 21. Comparison of options for availability criterion ................................................................... 36

Table 22. Comparison of options for water quality criterion ............................................................... 37

Table 23. Comparison of options for life expectancy criterion ............................................................ 38

Table 24. Comparison of options for aesthetics criterion .................................................................... 38

Table 25. MCA rating summary of all 14 combinations with weighted total ....................................... 39

Table 26. Options for small scale decentralised water treatment systems (Rajapakse, Waterman,

Millar, & Sumanaweera, 2014) ............................................................................................................. 57

Table 27. Total 48 combinations of options for MCA ........................................................................... 60

Table 28. Results of questionnaire for weighting of MCA criteria ........................................................ 65

Table 29. Maintenance schedule for rainwater harvesting system ...................................................... 66


VII

List of Figures Figure 1. Proposed development at the nursery. ................................................................................... 2

Figure 2. Map of bores throughout Rottnest Island. (Rottnest Island 1, 2014) ...................................... 3

Figure 3. Current water use at nursery ................................................................................................. 13

Figure 4. Flow of water through the Findhorn Living Machine system (Formosa, Mack, Roll, & Udell)

.............................................................................................................................................................. 23

Figure 5. Layout of the Currumbin water treatment system (Innoflow, 2009) .................................... 24

Figure 6. Schematic diagram of the CDM submerged membrane bioreactor treatment system

(Sharma, et al., 2012) ............................................................................................................................ 25

Figure 7. Schematic of the water filtration system at CH2. (Othman & Jayasuriya) ............................ 27

Figure 8. Summary of the waste water treatment methods ................................................................ 28

Figure 9. Image of water treatment facility at the Green Skills Building .............................................. 34

Figure 10. Average results of questionnaire, where lower value is considered more important ........ 40

Figure 11. Resulting weighted scores of 14 water system options ...................................................... 41

Figure 12. Assessment of sensitivity for criteria’s effect on options scores ......................................... 43

Figure 13. Final system flow model ...................................................................................................... 44

Figure 14. Model of greywater Treatment System (EMRC, 2014) ........................................................ 45

Figure 15. Estimated payback period for proposed water system ....................................................... 47

Figure 16. Schematic diagram of The Grove integrated water system (EMRC, 2011) ......................... 57

Figure 17. Communication with Ecoflo regarding options for composting toilet ................................ 59

Figure 18. Communication with Dynamic Supplies regarding options for composting toilet .............. 59

Figure 19. Part of communication with Waterwally regarding options for composting toilet ............ 60

Figure 20. Cost estimation of Advantex treatment system .................................................................. 62

Figure 21. Energy use estimation of Advantex treatment system........................................................ 63

Figure 22. Example of treatment system using advantex textile filters ............................................... 64

Figure 23. Notes regarding features of Advantex treatment system ................................................... 64

Figure 24. Approvals for installation of rainwater systems (Australian Government, 2008) ............... 67

Figure 25. Steps to aquire approval of GTS ........................................................................................... 68


1

1. Introduction and Background

1.1 Rottnest Island (Wadjemup)

Rottnest Island has a long and remarkable history. Now disconnected and 18Km away from

the coast of Western Australia, this island was once connected to the mainland before the

sea levels rose around 2500 years ago (Duggan, 2004). The island has strong indigenous ties,

with evidence of Aboriginal settlement dating back to 17,000 years ago (Collard, 2010).

Through the island's use as a prison, garrison and, as it still is, a holiday resort, there has

been a constant demand for fresh water. Initially, this water was received via roof

catchments of rainwater, the increasing demand made it necessary to seek additional

sources. The initial response was to add bores to access the groundwater, adding a brackish

source for non-potable use (Playford & Leech, 1977). The continuing increase in visitors and

residents on the island has continued to push the demand for water; this has resulted in salt

intrusion to the freshwater aquifers leading to a need for a desalination plant and a water

treatment facility (Environmental Protection Authority, 1991). With the number of people

on the island continuing to increase by an expected 62% in 2035, the pressures of water

scarcity continue to rise, exacerbated by the threat of climate change (Rottnest Island

Authority, 2014).

Due to its long-standing isolation, the environment on Rottnest has become specially

adapted but is vulnerable to human disturbance. With such a delicate ecology, the island

has been categorised as an ‘A’ class reserve to conserve the environment and cultural

heritage, the Rottnest Island Authority (RIA) has been charged with the handling of the

islands operations and management (Rottnest Island Authority, 2014). One of the duties

undertaken by the RIA is to coordinate a nursery for the propagation of native plants from

seeds and cuttings gathered from the island, which is to be used for revegetation projects

through the island (Rottnest Island Authority, 2014). This nursery has recently been the

focus of ongoing plans for redeveloping the island's infrastructure to improve long-term

sustainability, improve visitor experience, upgrade management and volunteering capacity

and better communicate the island's heritage (Chaney Architecture, 2015). As a part of this

upgrade the current nursery area will be expanded with the inclusion of a horticulture

centre to supply edible crops to the local community, the area will also gain an education

and interpretive centre, and facilities for long-term researchers such as accommodation,

ablution blocks and communal areas (Figure 1) (Chaney Architecture, 2015).

In keeping with the island's efforts to become more sustainable and environmentally

conscious, the RIA are seeking to develop this area so that it produces and reuses enough

water that it could remain decentralised from the island's main water supply, to design such

a system is the goal of this work.


2

Figure 1. Proposed development at the nursery.

1.2 Water on Rottnest

The water source for the island relies on two bore fields, the Wadjemup freshwater field on

the North-West of the island, and the saltwater bores at Longreach bay (Figure 2). The

saltwater bores are the main source of water for the island due to its long-term viability

(Department of Water, 2014), and produced 85% of the island’s needs (Programmed Facility

Management, 2014). The abstraction of this water is regulated by the Department of Water

(DoW), providing limitations to protect the water zones, for this case the limit is 120,000kL

per annum, while the actual combined drawn water from both sources is less, reported to

be 110,000kL per annum (Department of Water, 2014). This water is taken to the islands

reverse osmosis plant to be treated before distribution around the island.


3

Figure 2. Map of bores throughout Rottnest Island. (Rottnest Island 1, 2014)

The island currently used a mix of renewable and fossil fuel sources for it energy use, the

use of diesel incurs the additional costs of importing to the island. The cost of providing

energy and water resources on the island is greater than that on the mainland (Table 1); this

provides the push for the use of renewable energy and more sustainable water use

(Rottnest Island Authority, 2014). As well as the financial incentives there are also

environmental concerns to reduce the water use on the island, the bore fields on the island

are shallow and unconfined, making them susceptible to contamination, such as saltwater

intrusion and microbial contamination (Rottnest Island 1, 2014). With the upgrade of the

golf course on the island in 2013, the demand for water has significantly increased , this

along with the goal of increasing visitor numbers puts a strain on the existing infrastructure

(Rottnest Island 1, 2014), exacerbated by the reported increasing temperatures and reduced

rainfall for the island (Rottnest Island Authority, 2014).

Table 1. Water charges at Rottnest Island

Water cost $3.65/KL

Waste Water – Sewerage $348.90 annual Waste Water – Drainage $98.92 annual Waste Water Service Charge $796.94 annual Potable Water Service Charge

Min $94.05 annual Max $585.20 annual

The wastewater produced on the settlements of the island is treated on the island's

wastewater treatment plant, transferred through a sewer with a combination of pump and

gravitational methods. This wastewater is treated to a standard where it can be used on the


4

golf course and football oval easing the reliance on potable water, with the approval of the

EPA (Department of Water, 2014).

Further from the settlement, there is no sewer system. The toilets in these areas were

reliant on septic trench systems, the RIA has taken initiative to replace these existing toilets

with hybrid toilets (Parker Point), or composting toilets (Oliver Hill, Stark Bay and

Narrowneck). A comparison of these systems after installation noted that while both

worked, the hybrid systems were notably more expensive than the composting (Rottnest

Island 1, 2014).

1.3 One planet living and Earthcheck

One Planet Living (OPL) is an international organisation that provides a framework to guide

sustainable development by using ten guiding principles with the goal of encouraging

sustainability from communities, companies and governments (Bioregional, 2015). OPL uses

ecological and carbon footprinting as comparative measures in its assessments.

The principals given by OPL are:

Health and happiness

Equity and local economy

Culture and community

Land use and wildlife

Sustainable water

Local and sustainable food

Sustainable materials

Sustainable transport

Zero waste

Zero carbon

The RIA has previously used OPL as a guide in its assessments, and so for continuity it will

also be used for this review. Some of the principals will not be applicable to the project the

Sustainable Water section will be and so will be considered closely. This section relates to

this work by considering water efficiency and pollution from outputs, also, the recycling and

reuse of water could also fit into this section (City of Geelong, 2016).

Earthcheck is the other system Rottnest uses to assess its impacts. Earthcheck is a global

benchmarking, certification and environmental management programme for travel and

tourism. The programme considers: energy, carbon, community, paper, waste, pesticides,

cleaning products and water. The benchmarking is done initially by collecting data from

similar businesses and communities to compare the islands use with decided indicators,

followed by a comparison of this set benchmark to each successive year’s improvement.

Proof of performance is required and all improvements are awarded with certification

achievements of bronze, silver, gold and platinum for varying successes (Earthcheck, 2016).

The importance of attaining such certifications does not solely fall on the reduction of


5

environmental impact but also for tourism. Research has shown that 60% of tourists were

influenced by the inclusion of an eco-label, with 65% of them trusting in the eco-label (Logi

Karlsson, 2016)

1.4 Objectives

The aim of this work is to decide on the best suited, decentralised water system for the

expansion of the Rottnest Island's nursery.

This will be done through:

Finding the current water use at the nursery to extrapolate and predict the future

water use.

Consider the water sources available and assess if these sources will provide

adequate water.

Review and compare the options that could be used on the site for a water source,

toilets and waste water treatment.

Create a multi criteria analysis table that will compare the combinations against

various criteria of concern, which will be weighted to the stakeholder’s opinion of

importance. this will aid in finding the preferred arrangement

Finalise with a flow design of the idealised system.


6

2. Literature Review

2.1 Rainwater

Though a very old idea, the use of rainwater as a water source has drastically improved. This

has been done through the defining of components and parts for the design of the system

as can be seen in numerous books from a simplified guide with a target audience of

homeowners (Kinkade-Levario, 2007 and Dupont & Shackel, 2013) to the more complicated

technical analysis (Vieira, Beal, Stewart, & Stewart, 2014 and Pearce, Willis, Jenkin, & Wurst,

2005). Through these available sources, there are recurring elements describing the needed

components of the system, namely; catchment, conveyance, filtration, storage, distribution

and purification. Within these publications there is also the indication that there is a need

for monitoring the quality of the water with regards to the Australian standards, listed

throughout are items ranging from mosquito protection through to disinfection methods.

These journals and books outline the necessary elements of the system however they do

not give a comparison of the subsets of the elements (i.e. UV treatment compared to

chlorine dosing or filtration) to provide a discussion on which is preferable in which

situations. This comparison can be found within the Australian drinking water guidelines

(Australian Government, 2011), this provides a simple table that surmise five disinfection

methods and weighs their application in various considerations relevant to its effectiveness

at disinfection, health concerns and the need for technology through the process.

When considering the cost and benefit of installing a rainwater harvesting system, there are

numerous conditions to consider. Hajani and Rahman have proposed a repeatable method

used to compare the lifecycle cost analysis and the cost-benefit ratio by using peri-urban

regions throughout greater Sydney (Hajani & Rahman, 2014). They use the average rainfall

of each area on the average sized household site area and compared the cost saved on

water use by using different sized water tanks. Three categories of use were outlined for

comparison; toilet & laundry, irrigation, and combined toilet & laundry with irrigation. The

results were not surprising, with the areas of higher rainfall and the larger tank size allowing

for higher savings, thus a better cost-benefit ratio, the importance of this work is the outline

for calculating the various aspects of use in comparison. Their work was done by producing

a FORTRAN simulation, it seems simple enough to follow using a simpler program such as

Excel. Continuing this concern of feasibility and costs for rainwater harvesting systems,

Pearce et. al. review the potential for rainwater harvesting at the rural community Koonibba

(Pearce, Willis, Jenkin, & Wurst, 2005). This case has much in common with the Rottnest

project, as both are isolated from the larger population, and the concern over time for

replacement and repairs should the need arise. While the work is mainly focused on the

community’s perception of having a RWHS placed, there is still a discussion of the cost and

benefits of the installation for the community, including a comparison of installing a reverse

osmosis system to reduce the salinity levels in the mains water. Both community perception

and benefits have relevance to the Rottnest project the latter being the goal of the project,


7

as Rottnest is a tourist resort and home to residents the views of these both must be

considered with the implementation of a RWHS.

2.2 Desalination

Another well-documented aspect of water treatment systems is desalination. This has many

comprehensive works such as the journal article by Kalogirou, that outlines the science

behind the energy demands that are associated with the different types of desalination

methods, and discusses the options of renewable energy technology that would

complement the use of desalination methods (Kalogirou, 2005). The available information

on the workings of desalination technology also ranges from simple fact sheets aimed at

educating the public (Australian Water Association, 2016), to the more technical for industry

use such as Kucera’s work (Kucera, 2014).

While this process requires a large amount of energy to operate (Australian Water

Association, 2016), there is the opportunity to use renewable energy for this through the

application of solar thermal, solar PV, wind, hybrid solar PV and wind, and geothermal

energy, the choice of which would depend on the site and application (Kalogirou, 2005).

There are modelling methods for these systems available that can be used to ascertain the

size of the energy system, the amount of water produced and the energy used, thereby

easing the design of the system (Bilton & Kelley, 2015).

A comparison of the various technologies available for decentralised water treatment

technologies is provided by Rajapakse et. al. who as well as listing the possible technologies

provide a list of the significant pollutants each method treats (Rajapakse, Waterman, Millar,

& Sumanaweera, 2014). This work is significant as it looks at rural areas in Australia as well

as Sri Lanka, a focus that translates well to the scope of this project.

Desalination use through the world is also well recorded, some examples outside of

Australia shown are Singapore, China (Palmer & Porter, 2012), Honduras, Eritrea (Bilton &

Kelley, 2015), Israel, and more recently the San Diego California droughts have been singled

out where desalination came to be a significant aid (Talbot, 2014). Talbot also notes aspects

of desalination that are unfavourable showing the large energy use compared to other

sources, a factor again pointed out in Australian Water Association’s (AWA) fact sheet

noting each state's large capital and investment costs for the technology (Australian Water

Association, 2016). Talbot also mentions the environmental costs for this method through

killing marine life. A concern noted by the AWA is the “lack of assessment of desalination

versus treatment of natural catchment supplies” (Australian Water Association, 2016),

showing an area that is in need of further research to overcome a barrier for acceptance.

2.3 Greywater

Using greywater and wastewater for reuse in plant nurseries has been undertaken, with a

proven method in Italy (Lubello, Gori, Nicese, & Ferrini, 2004) and Jordan (Al-Jayyousi,

2003). Lubello et. al. note that with the increasing demand for water coupled with the


8

pressures to avoid high-quality water provides a drive to use alternate water sources for use

in irrigation purposes. Using greywater as this alternate source has its benefits on top of

water and cost saving, since the water contains higher levels of nutrients that aid the plants

in growth and fruiting (Lubello, Gori, Nicese, & Ferrini, 2004). Conversely, greywater

contains a larger pollutant load than that of rainwater (Al-Jayyousi, 2003), with an increase

suspended solids and BOD that has been reported to cause damage to plants (Lubello, Gori,

Nicese, & Ferrini, 2004). This latter limitation can be mitigated through the use of water

treatment methods, outlined and discussed by both Lubello and the Eastern Metropolitan

Regional Council. The former reviews the effects of a two-stage filtration and disinfection

system on the quality standards of the greywater, concluding that peracetic acid and UV

treatment were highly effective in the removal of E. Coli and total coliform indicators

(Lubello, Gori, Nicese, & Ferrini, 2004), while the latter reviews the costs for the installation

of such systems specifically referring to systems available and complying with the standards

of Western Australia (EMRC, 2011), this work goes into the cost-benefit analysis of installing

a system and notes that there is a rather large payback period of 6 to 15 years for the

installation of such a system, perceiving this as a limitation to the large scale acceptance of

greywater systems, this may change in future as the price of water increases.

2.4 Toilets

Using potable water for use in toilets is a poor use of the resource. As the goal of this

project is to produce an efficient water use system and avoidance of typical water-flushed

toilets would seem obvious. When comparing the water use of toilets, the main points of

technological comparisons are high efficiency, split stream, rainwater flushed and

composting toilets. A comparison of a combination of these (High efficiency, rainwater

combination rainwater with high efficiency, and composting) was conducted by Anand and

Apul (Anand & Apul, 2011). For this study, life cycle assessment, potable water demand and

wastewater production, energy use and economic analysis were used as points of

comparison. The concluding results showed that both rainwater and composting options

were viable in comparison to the commonly used methods when considering the economic

and environmental factors, but are not widely used. This study showed that the initial cost

of installing a composting waste system was highest, while its final running cost over an

estimated 50 year period ended up the least costly, produced the least emissions with the

lowest energy use with a reasonable 5 year payback period. There was discussion of factors

that may hinder the common acceptance of these types of systems including odour, the cost

and time needed to retrofit buildings for the composting toilets and planning needed for the

dual piping systems, also included was the unpredictable input from seasonal rainfall when

considering the rainwater flushed systems.

Anand and Apul provided a detailed outline of the full cycle of a composting system (Anand

& Apul, 2014). Following a brief history of the composting toilet system, the important

sections detail the component makeup of a composting system and compare the options.

The factors needing to be considered before choosing the size and type of composting


9

system is also described along with a brief discussion of the regulations and guidelines. The

main aspect of this paper is to fill in the gaps of knowledge for the utilization of composting

systems. Noted in the work is that there is not yet an accepted global regulation used for

the design of these systems, providing a barrier to the further advancement of using

waterless toilet systems, Anand and Apul do note other barriers that have been

encountered, most of which revolve around public awareness and negative perceptions

about the technology, many of which are pointed out to be unjustified. The paper concludes

with some case studies on composting toilets, these note a few issues found in the

implementation of these systems. Using these lessons Rottnest Island can go into this

project more prepared.

A recurring statement through these papers is that using the standard method of sanitation

is highly inefficient in its water use (Anand & Apul, 2011) and increased loss of water

through the hard-to-notice leaks in the pipework, which is exacerbated by the expansion

and increasing size of sewer systems (Anand & Apul, 2014). In comparison to this the

waterless option of composting toilets, which have a higher initial cost, are cheaper in the

long run due to the lower water and energy use (Anand & Apul, 2011). Rainwater flushing

systems have also been noted for their reduction of cost through less use of scheme water,

however this will still need to be connected to the wastewater infrastructure, giving it a less

desirable aspect over the composting systems (Anand & Apul, 2014). Another recurring

element is the lack of awareness and scientific comparisons on the topic, leading to

misguided views by the public (Anand & Apul, 2014), it has been noted that to overcome

this barrier there is a need for more awareness before these kinds of systems are more

widely used. One of the major obstacles is the fact that the excreta contain a large amount

of pathogens that can result in serious illness. Noted safe handling methods of the

composting products are multi-barrier uses with safe handling and sanitation (EcoSanRes,

2010), and if the composting is done correctly the heat produced will degrade and kill most

pathogens through the thermophilic phase (Anand & Apul, 2014). An alternative method to

this is to increase the pH, a widely used and successful method in developing countries

(Vinneras, Bjorklund, & Jonsson, 2003). Another issue brought up is the moisture content of

the compost (Anand & Apul, 2014). The addition of urine to the compost keeps it wet

creating unwanted anaerobic conditions, and this can be avoided by urine separation

methods. The benefit of this is not only the reduction of moisture, but also the compost

nitrogen levels can be kept down (Rauch, Brockmann, Peters, Larsen, & Gujer, 2003);

methods suggested for urine separation are urine separation toilets (Anand & Apul, 2014)

and the inclusion of urinals (Anand & Apul, 2011).

2.5 Effluent treatment

This project will assess the possible wastewater treatment methods for the decentralised

system. With this in mind Collado and Diez have provided a basic description of some

treatment options, comparing Infiltration trenches and beds, drained and non-drained sand

filters, infiltration mounds, drained horizontal sand filters, constructed wetlands and zeolite


10

filters (Collado & Diez, 2010). Even with this summary of comparisons, Sharma et.al. notes

that there is still a lack of knowledge regarding the overall systems in regards to their

performance, costs and energy use (Sharma, et. al., 2012). Kavanagh promotes that the

most durable option for an environmental water treatment system is the use of engineered

ecosystems, such as the one existing in Findhorn, Scotland (Kavanagh, 1999) (Formosa,

Mack, Roll, & Udell).

2.6 Legislation

Rainwater and its storage are covered greatly through various government publications,

both national and state. The rainwater tank design and installation handbook is an all-

encompassing source, covering from basic sizing and installation and treatment needed,

importantly this report outlines the different requirements that each state has for rainwater

systems as well as calculations for rainwater harvesting (Australian Government, 2008). The

enHealth report brings in a social aspect to the use of rainwater discussing the domestic use

and significance of this water source (Australian Government, 2004). While both of these

outline the various treatment methods, only the NSW government has a guide specifically

for the purpose for a comparison of the various methods (NSW government Health).

The guidelines given for the use of greywater in Western Australia provide a simple yet

thorough walkthrough of the steps needed for compliance. This covers its aspects in a step

by step fashion covering the guidelines to be met as well as management strategies

(Department of Health, 2011). This is furthered in another Department of Health paper that

also adds calculations to estimate the amount of greywater produced per household, as well

as discussing various treatment methods (Department of Health, 2010). The latter is aimed

at household use, the former leans that way also, with a brief discussion on areas with

multiple buildings and industry. These documents do not go into much depth on this idea,

suggesting that the average homeowner is the target audience. What the Western

Australian reporting lacks is a classification scheme for the recycled water quality as

Queensland has, giving a scale from class D to class A+ depending on the quality of the

treated water and the levels of bacteria, viruses, protozoa and helminths. This ranking helps

to classify the waters suitability for certain applications (Department of Energy and Water

Supply, 2008).

2.7 Water reuse at nurseries

As the nursery is the main consumer of water in this proposed development it is an

important factor to the current and future water use. To understand the water intake by

the processes there is a need for a water audit, Sturman, Ho and Mathew provide a general

outline for such undertakings (Sturman, Ho, & Mathew, 2004), the best practice guide by

the Nursery and Gardening Industry (NGI) provides a more precise method aimed for the

use in nurseries (Nursery & Garden Industry Australia, 2010). The information from this

provides the base from which a plan to reduce water use can be made. The NGI again

provides information here as does the NSW department of agriculture (NSW Agriculture,


11

2000), and importantly there is a discussion on both regarding the water sourcing and the

application of greywater reuse. The NGI goes as far as giving an equation to calculate the

amount of water available from rain and drainage from the reticulated area, while both

again go into depth regarding the limitations to water quality parameters and the options in

treatment and storage of this water. Here both books are supported by the Australian

government and promote the effective use and reuse of water through nurseries.

The reuse of irrigation water within a nursery is not without issue. As noted by Stewart-

Wade there is a chance of the accumulation of pathogenic microorganisms and increasing

the risk or outbreaks (Stewart-Wade, 2011). Here Stewart-Wade noted that for each of the

types of pathogen (bacterial, viral, nematodes), there needs to be a management practice

to maintain these below a hazardous threshold. The paper outlines detection methods and

a comparison of the physical, chemical and biological methods of treatment. This coupled

method of thresholds and treatment comparison is repeated in more depth by Salgot et. al.

(Salgot, Huertas, Weber, Dott, & Hollender, 2006), here values are assigned to the

parameters, unlike the previous work that only outlined the need for measuring. The need

for this testing is outlined by Mafia et. al. through their study of a recycled water system in a

Brazilian nursery. Mafia et. al. results show that although the reuse of water reduces the

demand for water and fertiliser, there was a high risk of accumulated pathogenic material

(Mafia, Alfenas, Ferreira, Machado, & Binoti, 2008).

2.8 Similar cases

Throughout Australia there are numerous eco island tourist resorts comparable to Rottnest,

mostly through the barrier reef in far North Queensland. A number of these have

revegetation programmes, yet none have implemented a recycled or greywater system.

These islands rely mainly on rainwater (Green Island Resort, 2005), and the use of reverse

osmosis plants (Green Island Resort, 2005). Closer to the project the Grove library has had

success in reducing water demand through alternate water sources and through the use of

onsite treatment has reduced reliance on a sewerage system (Shire Peppermint Grove).

Expanding the focal point, there are also larger island’s that have had the issues of

sustainability and water security discussed. The Croatian ‘Eco Island’ of Krk is one. Here

Nizic, Ivanovic and Drpic note the importance of a balance between sustainability and the

tourism market as Krk depends highly on the work brought from domestic and international

visitors (Nizic, Sasa, & Drpic, 2010). Although this work focuses more on the tourism aspect

of the island, the paper does note that if the goal is of being a sustainable tourist island then

there is a need for the island to produce a sustainable water supply management plan with

a reduction of natural spring abstraction, this is reminiscent of what is being seen on

Rottnest Island. Another similar case is the barrier island of Ocracoke in the US, where the

island has resorted to an on island RO plant as rainwater was not sufficient for the islands

demands. Further work is being done here due to an aged sewer system (Pompeii, 2016).


12

Away from eco-destinations, island communities are also noting the importance of tourism

on their water sustainability. One such case is the Spanish island of Majorca, a popular

tourist spot that is threatened by climate change. Kent et. al. state that the issues regarding

water here were first documented in the 1970’s and 80’s, showing the water demand trend

increasing past the availability (M. Kent, 2001). The response was to increase the

abstraction from inland aquifers, which resulted in saline intrusion, the same problem that

is occurring on Rottnest. Majorca’s issues had other proposed solutions. The construction of

reservoirs and shipping of fresh water from mainland Spain, both of which would not be

suited for Rottnest due to space and cost constraints. The final solution presented here is

through the ‘Proposal for a Hydrological plan for the Balearic Islands’ in 1998, outlining goals

emphasising the need for increased use of recycled and treated water among others, this

goal is shared in the scope of this project.

Hawaii has also been found to have the same problem of a large tourism water footprint;

Saito’s work considers the water food and energy consumption on the island and compares

it to the number of establishments, visitors and jobs (Saito, 2013). Through the data

gathering, it was found that the tourism on the island accounted for 44.7% of the entire

island’s water consumption, with the golf course and accommodation the biggest users. This

situation is noticeably similar to Rottnest (Rottnest Island 1, 2014). Saito gives no suggestion

in how to alleviate the problem, instead discusses how this collected data could be used in

improved management decisions; this would be beneficial to Rottnest Island as a whole,

possibly coming to consideration with the creation of a management strategy.

There has also been work done into the effects of tourism and ecotourism on sustainability

and the impacts on water availability. Kavanagh provides a thorough review of water

management at tourist attractions through Queensland (Kavanagh, 1999). This provided

four conclusions: A water source hierarchy, with rainwater use being prioritised over bore,

spring or river water and that in turn preferred over mains; The water used should be done

so sparingly with the use of water saving devices, composting toilets, xeriscaping and similar

practices; Wastewater should be treated with minimal chemical and energy inputs, while

still reaching standards that allow reuse; and all treated wastewater should be reused.

These conclusions are suited well for Queensland where the rainfall, and thus the potential

alternate water availability are high; this does not pass well to Western Australia where the

rainfall is generally lower, still the other points hold validity.


13

3. Methods used to find water use To gain an understanding of the current water use at the existing nursery, the appliances on

the site will be reviewed to model the needs that the proposed project will have.

3.1 Current water use

Along with the majority of the island, the nursery’s current water source is from the island’s

mains water supply. This water is drawn from saltwater bores on the northern face of the

island and fed through the desalination plant (Department of Water, 2014).

A flow chart is illustrated in figure 3 to demonstrate the current water situation of the

nursery. Here it can be seen that there is one input for water, the scheme water from the

desalination plant, and two outputs, overflow gets piped into the surrounding vegetation

while waste water from potable uses goes to the waste water treatment plant via the

sewerage system. The uses of water at the nursery involve numerous appliances, this use

includes: two sinks, one in the kitchen area and one in the bathroom, dual flush toilet,

shower, three exterior taps and the sprinkler system.

Figure 3. Current water use at nursery

This area also includes non-commercial accommodation for researchers who are conducting

long-term fieldwork on the island (Rottnest Island Authority 2, 2014). Here the facilities

include three sinks, two toilets, shower and laundry.

3.2 Water audit

The site does not currently have a flow meter on the water system so to find the current

water use of the nursery, a water audit has been undertaken. To do this, the water flow


14

from each appliance was assessed. This was done for most equipment by using the bucket

and stopwatch method. This follows the outline proposed in Water Auditing and Water

Conservation (Sturman, Ho, & Mathew, 2004). For the toilet, the water used for each flush

was found through the model of the toilet. The flow rates found are listed in Table 2. The

use of this site fits into two categories: The overnight stays and the day visits. The former

refers to researchers staying in the accommodation while the latter covers employees,

volunteers and visitors to the site.

Table 2. Flow rates of appliances found on site at nursery

Appliance Volume (L) Time (s) Flow rate (L/min)

Kitchen tap 0.591 3.9 9.09 Bathroom tap 0.532 2.8 11.4 Shower 0.591 4 8.9 Sprinkler type 1 0.22 9.3 1.4 Sprinkler type 2 0.213 24.4 0.5 Animal tap 0.591 5.3 6.7 Overhead tap 0.591 3.8 9.3 Front tap 0.591 3.5 10.1 Toilet 3L for half flush, 6L for full flush

3.2.1 Overnight stay water use

The faucets have a varied time depending on its use, 5-30 seconds is a reported average

range (Alliance for water efficiency, 2016). At the site there are two interior taps, one in the

toilet and one for the kitchen, and three exteriors. Evaluating the use of the interior taps,

the kitchen will be given a 30-second use, while the toilet will be given 10 seconds, the use

of these will be once per person for the Kitchen and once per use of the toilet for the

bathroom tap, that being three times per person. The exterior taps are used for work

purposes, such as tool wash downs, and so do not rely on the number of people present.

Instead, this is assumed to be used for three minutes per day.

Similarly, the sprinkler system does not rely on the occupant number, rather the sprinkler

system is on a timer with a varied length depending on the season and species watered,

through discussions with those working in the nursery it was revealed that a rough estimate

of this would be 20 minutes, 3 to 4 times a day, varying with season and type of plants being

watered. The sprinkler system has two different nozzles with different flow rates, both of

which have been taken into consideration.

Again through discussions with those who work in the building, it was found that the shower

was used very little, possibly once a month, along with the average shower length of 6.7

minutes (Water Corporation, 2009) the water use of the shower can be determined. The

average use of a toilet is two half flush and one full flush per person per day (Alliance for

water efficiency, 2016); the existing toilet gives 6L for full and 3L for a half flush.


15

The average yearly use of washing machines is 8 kL a year, gives an approximate 22 L use

per day (Water Corporation, 2009), along with an assumption that this will not be used by

single night stays, but those staying for multiple nights, for this report an estimate of four

days has been decided thus 5.5 L per day is used on the laundry. With the flow rates and the

approximate appliance use a model has been made to calculate the rough water use in the

nursery calculating for varying number of people (Table 3).

Table 3. Calculation of water use per person for overnight stay

People 1

Appliance Q (L/s) Time (s) Person/Single use Period Water use (L) Kitchen tap 0.15 30 Person Day 4.5 Bathroom tap 0.19 10 Person Day 5.7 Shower 0.15 13.4 Use Day 2.01

Sprinkler type 1 0.024 3600 Program Day 86.4 Sprinkler type 2 0.009 3600 Program Day 32.4

Outdoor taps

0.112 180

Use

Average daily

26.22

0.156 0.169

Toilet 3/6 2/1 Person Day 12 Washing Machine

22 L 1 use Use 4 days 5.5

Total per day 174.73 Yearly use (kL) 63.78

3.2.2 Day visit water use

The day visitor’s data is based on the same flow rates as the previous data with different

use. For this, the sprinkler water use and washing machine use have been omitted, and the

exterior tap use reduced to an assumed one-minute use. This leaves the kitchen tap,

bathroom tap, toilet use and shower times the same as with the overnight stays (Table 4).


16

Table 4. Calculation for water use for day visitors

People 1

Appliance Q (L/s) Time (s) Person/Single use Period Water use (L) Kitchen tap 0.15 30 Person Day 4.5 Bathroom tap 0.19 10 Person Day 5.7 Shower 0.15 13.4 Use Day 2.01 Sprinkler type 1 0.024 0 Program Day 0 Sprinkler type 2 0.009 0 Program Day 0

Outdoor taps 0.112

60 Use Average day 8.74 0.156 0.169

Toilet 3/6 2/1 Person Day 12 Washing Machine

22 L 0 Use 4 days 0

Sum 32.95

Yearly use (kL) 12.03

3.2.3 Confidence of calculated data compared to industry data

To confirm the calculated use, a comparison was performed with the industry data. In the

information provided in the AS/NZS 1547:2000, the closest premises aligning with the use of

the overnight stays at the nursery could be the motels/hotels, with the guest and resident

staff subsection. This classification gives an estimated 180L of water per person per day

(AS/NZS 1547:2000, 2000), using this in comparison with the calculated data gives 97.07%

confidence, well within the 10% confidence interval needed (Sturman, Ho, & Mathew,

2004), making this assumption of water use reasonable.

The day visitors would fit into the non-resident staff section of this classification; this 30 L

per person per day (AS/NZS 1547:2000, 2000). This gives a 91.04% confidence interval, again

within the acceptable 10% limit (Sturman, Ho, & Mathew, 2004).

Using these data the projected future use can be estimated as in Table 5, where the

expected use is 100 people per day as noted through contact with the Rottnest Island

Authority (RIA). Of this 100 people, the proposed development will have potential to

accommodate 25-30 people for overnight or long term stays, the model will use 30 and 70

for the day visitors.

Table 5. Calculation of total daily and yearly use from two sources

Model Daily use (L) Yearly use (L)

Calculated 7548.4 2,755,166 AS/NZS 1547 7500 2,737,500


17

4. Options considered for nursery system There are three distinct sections for consideration, that being; the source of water, the

appropriate use of water, and the effluent from the site. The first is a simple definition of

how the site will attain the water used. The third section applies to how the wastewater will

be treated before release. The use of water on site generally relates to the use of water

efficient appliances and so has been left to the discretion of the RIA. What has been

considered, are the various options of toilets and the addition of water recycling through

greywater systems. The latter has been included in the initial water source section for

simplicity.

4.1 Water sources

The main source of water for the island is the reverse osmosis treatment plant that procures

its potable water from the aquifers on the island. While this method is well used and

proven, the use of this system does not align with the RIA goals or the standards set out by

implementing the OPL and Earthcheck benchmarks. Therefore as an alternative to this

method other sources of water will need to be found and evaluated to see if it would be

practical for the development.

Modelling of water capture was done through a Matlab program. This program calculated

the amount of rain available daily for use using historical data, area of capture and

percentage of this available. The program allows for the inclusion of both drainage

catchment and solar powered pumps for groundwater abstraction either individually or

together to allow calculations for all combinations. The calculated daily input was compared

to the inputted daily use, with surplus water stored in a water tank with adjustable storage

capacity. The program was designed to output the amount of water captured, amount of

water used and total number of days where the daily use was greater than the input

(Appendix 9.8).

4.1.1 Rainwater

For islands with limited fresh water aquifers, rainwater harvesting has been prominent

when considering alternative sources of water. For Rottnest there is a limited choice when

considering alternatives, thus rainwater would be considered as a significant option for

water. However, Rottnest, similar to the rest of south-west of Western Australia, is

experiencing a reduction in rainfall, to about 15-20% from the mid 1970’s figures (Stocker,

Burke, Kennedy, & Wood, 2012). Therefore this signifies a limitation in the availability of

rain available to be captured for use, yet it is still the preferred option of water sourcing

with reference to the RIA’s environmental goals and the objectives of OPL and Earthcheck.

As the Wadjemup conservation centre will consist of three buildings, the catchment area

will consist of the buildings roofs, referring to the proposed plans for the development, the

three buildings have a footprint of 910m2, 195 m2 and 112 m2 for a total catchment of 1217

m2 (Chaney Architecture, 2015).The area of catchment could be increased through smart

design of the buildings and inclusion of covered walkways between.


18

There is also an opportunity to use stormwater, this will have a higher risk of contamination,

so a more proficient purification system would need to be introduced (Kinkade-Levario,

2007). As the intent of this water is to be used as a potable source, the caught stormwater

needs to be purified to be brought to a suitable quality, this would include: Screening;

filtration; disinfection and pH control (Kinkade-Levario, 2007).

It was found through the Matlab program that the rain is not a sufficient source of water for

use, and is only able to provide 528L of the 275kL per year demand (Appendix 9.8).

4.1.2 Water reuse: Greywater and Drainage capture

There are limitations on the use of greywater as it may be a pathway for the transmission of

bacteria, because of this potable use is avoided, and four non-potable uses have been

approved by the department of health. The use of greywater for these applications depends

on the intensity of treatment methods that is surmised in Table 6 (Department of Health,

2010). The disinfection standards referenced in Table 6 refer to the maximum level of BOD

(mg/L), suspended solids (mg/L) and E.coli (/100mL), respectively, while the AGWR standard

referred to is the Australian guidelines for water recycling. From this table, it can be seen

that for any productive use of the collected greywater, there needs to be a greywater

treatment system in place with a significant level of treatment.

Table 6. Approved uses of greywater for commercial premises (Department of Health, 2010)

Treatment method Permitted use of greywater sourced from and

recycled on multi-dwelling/ commercial premises

Bucketing

Subsurface irrigation N/A

Surface irrigation N/A

Toilet flushing No

Washing machine No

Diversion device

Subsurface irrigation No

Surface irrigation No

Toilet flushing No

Washing machine No

Greywater treatment system with no

disinfection (20/30 standard)

Subsurface irrigation No

Surface irrigation No

Toilet flushing No

Washing machine No

Greywater treatment system with

disinfection (20/30/10 standard)

Subsurface irrigation Yes

Surface irrigation Drip Only

Toilet flushing No

Washing machine No

Greywater treatment system with

disinfection (10/10/1 standard)

Subsurface irrigation Yes

Surface irrigation Drip Only

Toilet flushing AGWR standard only

Washing machine AGWR standard only


19

In addition to the greywater the drainage water from the nursery can be captured for reuse,

and it can be calculated by:

𝐷𝑟𝑎𝑖𝑛𝑎𝑔𝑒 𝑉𝑜𝑙𝑢𝑚𝑒 𝑚3 = (𝐴𝑟𝑒𝑎 𝑚2 𝑥 𝑅𝑎𝑖𝑛𝑓𝑎𝑙𝑙 𝑚𝑚

1000) + (𝐴𝑟𝑒𝑎 𝑚2 𝑥 𝐼𝑟𝑟𝑖𝑔𝑎𝑡𝑖𝑜𝑛

𝑚𝑚

1000).

(NSW Agriculture, 2000)

The nursery has an approximate area of 440m2 with the addition of the future horticulture

area of 280 m2 gives a total area of 720 m2 of reticulated zone able to be captured (Chaney

Architecture, 2015). The rainfall for the area can be found through the Bureau of

Meteorology (Bureau of Meteorology, 2016). The irrigation time for the nursery also varies

with seasons, with the maximum being 20 minutes, four times a day during the peak of

summer as noted previously. The flow rates for two types of heads in the irrigation system

were measured for Table 2, these were found to be 1.4L/min and 0.5L/minute.

Using the aforementioned Matlab program (Appendix 9.8), the addition of the drainage

calculation with the rain capture provides an additional 366L for the year. This gives a total

of 894L per year at the site, again not matching the needed 275kL

4.1.3 Saltwater desalination

As well as the option to use the groundwater bores, there is the opportunity to use the salt

water Lake which the nursery is adjacent to. These are permanent natural features on the

island (Rottnest Island Authority, 2016), having these sources of water nearby could provide

the conservation centre with its source of water. This option will give a large initial supply of

available water it will also need treatment from the source to be at a usable standard.

This is a commonly used method to attain freshwater globally and is the current method

used at Rottnest Island. There are still barriers to its acceptance, the strongest of these

being the large implementation and running costs along with detrimental environmental

effects from the saline rejection stream, increased waste from used membranes and from

energy consumption (Australian Water Association, 2016).

There are several methods existing that are used to produce suitable water from a

groundwater source (Appendix 9.2). These options are categorised as household level,

small-scale system or can vary in size for both, as the household scale is only able to provide

up to 150L per day these are not enough for the Rottnest project (Rajapakse, Waterman,

Millar, & Sumanaweera, 2014). The various technologies are also differing through the

pollutants they treat. Looking at the provided choices, the only two options that are small

scale and that treat significant contaminants are the slow sand filters (SSF) and membrane

filtration (Rajapakse, Waterman, Millar, & Sumanaweera, 2014). Of these, the SSF option

would prove to be most suited due to its low maintenance, chemical free operation and

high pathogen removal (Logsdon, 2008), where the membrane filtration system would be

larger in size and use a significant amount of energy and cost (Rajapakse, Waterman, Millar,


20

& Sumanaweera, 2014). This SSF method would need to include chlorine dosing in the

system for residual treatment (Corral, et al., 2014).

With the previous findings that both rain and recycling of water would not reach the

modelled site demand, the use of on-site desalination remains the only viable option. This

could be done in conjunction with RWH and greywater or alone to suit the desired outcome.

Furthering this, the Matlab program was used with the option of a solar powered pump

along with the drainage and rainwater capture. The final values indicated this combination

would suffice to draw enough water to supply the development (Appendix 9.8).

4.2 Toilets

To achieve the goal that this facility will be self-dependant, the ablution facilities will need

to be independent of the island's main water, sewer and electrical systems while remaining

an adequately sustainable sanitation service (Humphreys, 2014).

4.2.1 Rainwater and greywater flushed systems

The continuation of using a dual flush toilet system has the benefit of being a well

understood and publicly accepted method of use. The introduction of a non-potable water

source for the flush mechanism would alleviate the dependence on a limited potable supply

while a decentralised treatment system (Section 4.3) would negate the need for use of the

island's wastewater treatment plant. The current water efficiency labelling standards (WELS)

minimum requirements for toilets state that the average water use should not exceed 5.5L,

this average is taken from one full flush and four half flushes, a summary of the WELS rating

scheme is provided in table 7 (Australian Government, 2016). By reviewing common stores

that sell toilets (Bunnings, Reece, Caroma Harvey Norman) the seemingly most common

rated toilet is the 4 star rated toilet, this would indicate that if this method was chosen, then

there is an ease of availability for the more water efficient options. Using the same sources,

there is a price range from $150 to $2000. For this project it will be assumed the more lavish

options will be avoided.

Table 7. WELS rating for appliance water use

Product Units 1 Star 2 Star 3 Star 4 Star 5 Star 6 Star

Shower L/min >12 to 16 >9 to 12

7.5 to 9 - - -

Taps L/min >12 to 16 >9 to 12

>7.5 to 9 >6 to 7.5 4.5 to 6 Less than 4.5

Toilets

Full flush L/Flush

9.5 max 9.5 max

6.5 max 4.7 max - -

Half flush L/flush

4.5 max 4.5 max

3.5 max 3.2 max - -

Average flush L/flush

5.5 4.5 4 3.5

3 With integrated basin

-


21

4.2.2 Composting toilets

Composting toilets are already in use on the island. The areas away from the main

settlement do not have access to either the main water supply or the sewage system.

Instead, the original toilets relied on septic trenches for the waste removal. The leachate

from this method was believed to be causing an impact on the surrounding marine

environment, so this system was replaced by composting toilets (Rottnest Island 1, 2014).

The Department of Health provides a list of approved waterless toilets for use in WA

(Department of Health, 2016), limiting the choice to only the approved models leaves four

manufacturers to consider. These still provide numerous options through the possibilities of

dry composting and micro-flush toilets, natural or fan based ventilation, and the option of a

hybrid toilet that also allows for composting with the inclusion of urine, not separation as

standard composting toilets do (Anand & Apul, 2014). Furthermore, the different models

will accommodate the use of a varying maximum number of people.

Through consultations with the companies Ecoflo, Dynamic supplies and Waterwally

(Appendix 9.3) all came to the conclusion that with the proposed plan and availability that

the Clivus Multrum would be the preferred option. This still leaves the options open for

varying numbers of toilets and pans with separation for male, female and disabled access.

4.3 Effluent

In keeping with the goal of this project, the options for treatment and disposal of

wastewater will focus on a decentralised option. As the effluent has a large number of

options through various combinations for primary, secondary and tertiary treatment before

release, this work will not assess each possible arrangement; instead existing, proven

examples will be reviewed and appraised to see if they will suit the Rottnest Island setting.

These options have been chosen due to their success and significant difference and

uniqueness from each other.

4.3.1 ‘Living machine’: Findhorn

The wastewater from Findhorn eco-village in Scotland is treated through a system of ‘Living

machines’. These systems simulate and hasten the natural water treating principles that

exist in wetland ecology by use of bacteria, algae, microorganisms, macroorganisms and

plant life (West, 2000).

The system consists of six steps to treat the wastewater (Figure 4). The first is a primary

treatment through use of a septic tank. Here the water is separated into settled solids, scum

and effluent, as the tank provides an anaerobic environment it gives rise to anaerobic

microbes that break down organic and inorganic matter. The effluent flows into an anoxic

reactor where further treatment via microbes occurs. At this step, the microbes convert

nitrates into nitrogen gas. The following process is a closed aerobic reactor where air is

bubbled through the bottom of the tank removing any anaerobic bacteria and allowing for

an environment for aerobic bacteria to convert ammonia into nitrates and further break

down organic matter. A layer of plant material scrubs the escaping gases to remove any


22

odour. The fourth step is the aerobic tanks where a diverse ecosystem of plants, algae,

microorganisms and macroorganisms further treat the water, this is done through nutrient

removal, metal sequestering, pathogen destruction and gas exchange. Solids from this stage

are removed by use of a clarifier; these solids are cycled back into the primary treatment

septic tank while the water proceeds to the fluidised beds. These beds provide the final

polishing of the water, acting like a natural wetland. The beds are filled with a porous

material providing surfaces for biofilm to grow and further treat the water. After this final

stage, the water is available for use in non-potable applications with the effluent having

quality listed in table 8 (Formosa, Mack, Roll, & Udell) (Findhorn Ecovillage, 2000) (West,

2000) (Biomatrix Water, 2012) (Laylin, 2010).

Table 8. Final water quality parameters for Findhorn water treatment method

Parameter Influent Effluent

BOD 250mg/L <10mg/L TSS 160mg/L <10mg/L TKN 40mg/L <10mg/L NH4 50mg/L <2mg/L NO3 0mg/L <5mg/L TP 7mg/L <5mg/L

The existing system in Findhorn was implemented in 1996 and is designed for a capacity of

up to 65 kL a day, the current 200 residents only produce 50 kL (West, 2000). The inclusion

of a variety of communities of bacteria, algae, micro-organisms and plants allow the system

to be resilient to any shock loads and fluctuations in pH, toxins and load. This would

translate well into Rottnest due to the large fluctuations in visitors through the seasons

(Formosa, Mack, Roll, & Udell), as well as having the systems above ground and visible

providing a visual learning opportunity as is the goal of the site expansion.


23

Figure 4. Flow of water through the Findhorn Living Machine system (Formosa, Mack, Roll, & Udell)

4.3.2 Currumbin textile filters

Currumbin eco-village caters to 144 homes of various sizes along with community facilities.

This village is off the grid for its water supply and treatment (The Ecovillage at Currumbin).

The treatment plant at the Ecovillage is designed to treat 60 kL per day (Innoflow, 2009).

Figure 5 shows the layout of the waste water treatment facility at Currumbin eco-village.

Here the effluent from the village is taken to the primary treatment tanks that consist of

three communal septic tanks, allowing the removal of solids and scum (Larsen, Udert, &

Lienert, 2013). The six recirculating textile filters for the secondary treatment are Orenco

Advantex filters that use attached growth for oxidation, biofiltration and Nitrogen reduction

(Orenco systems Inc, 2016) (Orenco systems Inc, 2014). Following this is the treatment to

remove the final biological contaminants, this includes a Memcor microfiltration system, UV

disinfection and chlorine dosing (Hood, et al., 2010), the combination of which produces

recycled water that complies to Queensland’s public health acts classification of class A+

water (Table 9) (Department of Health, 2008), this water is now available for reuse however

it does not comply with drinking water standards and can only be used for non-potable uses

(Hood, et al., 2010).


24

Figure 5. Layout of the Currumbin water treatment system (Innoflow, 2009)

Table 9. Final water quality parameters for Currumbin water treatment method (Innoflow, 2009)

At the site this water gets reused in the residential areas for toilet flushing and garden

irrigation, and as the residents demand is less than that produced the additional supply is

sent for use by communal spaces for further reticulation needs. Some of this is kept in

storage for future use (Hood, et al., 2010).

Parameter Required value Queensland EPA

Actual performance

BOD5 10mg/L 3.37mg/L Suspended solids 10mg/L 1.85mg/L Total Nitrogen 15mg/L 14mg/L E.coli <10 Cfu/100ml 1cfu/100ml Viruses and pathogens

5 log removal 9 log removal


25

4.3.3 Capo di Monte Membrane bioreactor

The Capo di Monte (CDM) retirement village is a 43 ha, self-sustaining, 46 house

development that utilises a decentralised water treatment system (Chong, Ho, Gardner,

Sharma, & Hood, 2011). The area has a population of 100 people with a community centre

and public facilities (MWH, 2010). The treatment plant is designed to treat 11kL of waste

water per day (Sharma, et al., 2012).

The focus of the waste water treatment at CDM is the submerged membrane bio reactor

(Figure 6). This reactor follows a screening filter, and contains both an anoxic and aerobic

zone; the second of these contain a submerged membrane bioreactor with a pore size of

0.1µm, thereby excluding solids, bacteria and viruses to continue through the process

(Sharma, et al., 2012). The water undergoes carbon substrate degradation and nitrification

in the aeration zone. Phosphorous is removed using Alum and the final tertiary treatment

uses UV and chlorine treatment (Chong, Ho, Gardner, Sharma, & Hood, 2011). This method

also produces A+ class of water through its treatment, and is used in the residential areas

through a dual pipe system for toilet flushing and reticulation (Table 10); any excess is

diverted from the local waterway by applying it to a vegetated buffer zone (Sharma, et al.,

2012).

Figure 6. Schematic diagram of the CDM submerged membrane bioreactor treatment system (Sharma, et al., 2012)


26

Table 10. Final water quality parameters for CDM water treatment method

Parameter Units Ecovillage (Average) License

Testing Frequency

Turbidity NTU 0.3 <2.0 Continuous pH - 7.0 6.0-8.5 Weekly Free Cl2 mg/L 1.4 >1.0 Daily Total Nitrogen mg/L 12.5 <15 (45 Max) Monthly Total Phosphorus mg/L 2.9 <10 (30 Max) Monthly Dissolved O2 mg/L 7.3 >2.0 Weekly BOD mg/L <3 <10 (30 Max) Monthly Suspended Solids mg/L <2 <10 (30 Max) Monthly E. coli Cfu/100mL <1 <10 Weekly

4.3.4 Council House 2, Multi water reuse

Council house 2, commonly known as CH2, it is a ten storey office building located in the

CBD of Melbourne. This building's reputation comes from it being the first purpose built

office building to reach the Green Buildings Council of Australia’s six-star rating (City of

Melbourne, 2010). The water treatment at this site boosts the treated water produced in

the building through sewage mining of the mains passing under the building, allowing for

flexibility of the treatment system through low use periods (CRC Construction Innovation,

2007). This system is designed to take 100kL of water, it has treated as low as 20kL without

adverse effects (City of Melbourne).

The system at the CH2 building consists of a three stage filtration process, as shown in figure

7 (Othman & Jayasuriya). The first of these is a 200-micron pre-screening filter. As the mined

sewerage is 95% water (Hes & Cummings) such a small filter size works fine. The collected

solids, in all the filtration steps get returned to the sewer. The second filtration step is a

ceramic ultrafiltration unit, this consists of tubular membranes of 0.02 microns, with this

size the majority of suspended solids, bacteria and viruses will be removed, screenings from

this second filter is used to wash the filtrate on the first (Hes & Cummings). This leads to the

final step in the system which is the reverse osmosis unit. This acts as a filtration and a

disinfection process as after this step approximately 95-99% of the dissolved solids and 99%

of all bacteria have been removed, the final water has the quality parameters listed in table

11, giving it a class A rating (Hes & Cummings). Following these filtration processes is dosed

with chlorine or residual disinfection (CRC Construction Innovation, 2007). The water

produced is reused within the building for non-potable purposes as irrigation water, toilet

flushing, street and open space washing, and for the cooling system (CRC Construction

Innovation, 2007).


27

Figure 7. Schematic of the water filtration system at CH2. (Othman & Jayasuriya)

Table 11. Final water quality parameters for CH2 water treatment method

Parameter Screened Sewage

Microfiltration Filtrates

Reverse Osmosis Permeate

Biochemical oxygen demand, BOD (mg/L)

230 89 < 2

Total organic carbon, TOC (mg/L) 103 46 0.8 Suspended solids, SS (mg/L) 144 <2 - Total dissolved solids, TDS (mg/L) - 103 12 Total Kjeldahl nitrogen, TKN (mg/L) 50 51 5.5 Total phosphorus (mg/l) 11.2 9.0 0.03 Faecal coliforms (cfu/100 mL) 5.1X1033 1.3 <0.1

4.5 Flow options

The effluent treatments options outlined in the previous sections are summarised in figure

8. Notably, the maximum wastewater volumes that can be treated by each option are

greater than the estimated amount produced at the proposed site. These systems can run

and keep an average below this maximum level without issue, this also provides the

opportunity to develop a smaller scale version of these methods to lower costs and

footprint.

Recapping these rates:

Findhorn maximum 65kL

Currumbin maximum 60kL

CDM maximum 11kL

CH2 maximum 100kL


28

Summary of effluent options considered

PrimaryModel Secondary Tertiary

Findhorn

Currumbin

Capo di Monte

CH2

Septic tank

Settling tank

Screening

Screening

Anaerobic Anoxic Aerobic Filtration beds

Textile filters

microfiltration UV and Cl

Anoxic Aerobic UC and Cl

Membrane filtration

UV RO

MBR

Figure 8. Summary of the waste water treatment methods

Through combining the outlined options there are numerous arrangements for the final

system, having a total of 48 unique groupings (Appendix 9.4). Some of these options will not

be considered in the upcoming MCA due to the following constraints.

One such constraint is the availability of water from rain catchment. As noted in section

4.1.1 and 4.1.2, RWH by itself or in combination with drainage reuse does not meet the

needed water demand, as such, only options that have desalination or desalination in

combination with the RWH system are considered. Furthermore, options without a

greywater treatment system are removed from the final options to help minimise demand

of potable water.

The CH2 model is based on the use of minimal solids for the filters, thus the options with

reclaimed water-flushed toilets combined with the CH2 model have been removed with the

preference of composting toilets with this effluent treatment method. This leaves 14

combinations for the final MCA consideration (Table 12).


29

Table 12. Final 14 combination options for MCA

Option number

Input Greywater reuse

Toilet Effluent model

1 Desalination Yes Reclaimed water flushed Findhorn 2 Rain and Desalination Yes Reclaimed water flushed Findhorn 3 Desalination Yes Reclaimed water flushed Currumbin 4 Rain and Desalination Yes Reclaimed water flushed Currumbin 5 Desalination Yes Reclaimed water flushed Capo di Monte 6 Rain and Desalination Yes Reclaimed water flushed Capo di Monte 7 Desalination Yes Composting Findhorn 8 Rain and Desalination Yes Composting Findhorn 9 Desalination Yes Composting Currumbin

10 Rain and Desalination Yes Composting Currumbin 11 Desalination Yes Composting Capo di Monte 12 Rain and Desalination Yes Composting Capo di Monte 13 Desalination Yes Composting CH2 14 Rain and Desalination Yes Composting CH2


30

5. Multi-Criteria Analysis From the 14 previously noted options a multi-criteria analysis table will be constructed using

ten different categories with the intent to cover the triple bottom line of economic, social

and environmental topics. These considerations are compiled into the final MCA table and

assessed against each other (Table 25). From table 12, it can be seen that there are three

points of comparison for each option, that being:

Desalination or rainwater and desalination for water source,

Reclaimed water-flushed toilet or composting toilets for onsite use

Findhorn, Currumbin, CDM or CH2 model as the effluent treatment method.

The following criteria will help rank these points singularly before combining them in the

final MCA

5.1 Cost

As the options for water sources vary only through the addition of the RWH option, it would

be intuitive that the option with all three (RWH, greywater and desalination) would be more

expensive than that with only the two (Table 13). Notably, the cost of desalination is larger

than that of RWH (Australian Water Association, 2016).

In consideration of the costs of toilets, the composting option has a significantly larger initial

cost (Table 13). The Department of Health provides a list of approved waterless toilets for

use in WA (Department of Health, 2016), limiting the choices to only the approved models

leaves four manufacturers to consider, through consulting with members in the industry all

suggest that the Clivus Multrum would be the best option, due to its availability, ease of use

and capacity. This manufacturer has toilet systems that are all over $7000 (Appendix 9.3)

with the additional cost of additives needed for successful composting such as bulking

material. The comparison of these two options has been done previously (Anand & Apul,

2011), where it was also noted that the initial cost was over $6000 higher for the

composting option. Over the 50 year assessment that was done in this work it showed that

the composting option was the most cost beneficial in the long run, having a 5 year payback

period compared to 9 for the rainwater flushed system.

The system in Findhorn cost an initial £140,000 with an annual operating cost of £22,400

through electricity use and labour (West, 2000). Converting this to Australian dollars, the

average exchange rate in 1996 was 0.5023, thus giving $267,680 for the initial cost and

$42,828.80 for the yearly expense (Australian taxation office), and then taking into account

inflation gives an estimated $436,367.90 and $69,818.86 respectively for this project

(Reserve bank of Australia). The Currumbin options main feature is the textile filter; this is

estimated to cost $87,860, with an operating input of $1.05/day (Appendix 9.5). CDM

capital cost was $312,109 while its operating cost is $1.57/kL (MWH, 2010). The cost of the

CH2 system is unavailable, using a similar project it has been given a cost of $900,000 (De

Groot, 2013) (Table 13).


31

Table 13. Comparison of options for cost criterion

Preferred options: Cost

Source Toilet Effluent 1 2 1 2 1 2 3 4

Desalination Rainwater and desalination

Composting Rainwater flushed

Currumbin CDM Findhorn CH2

5.2 Footprint

Having both rainwater and desalination options would take up more space than the

desalination option by itself (Table 16).

The size of the reclaimed water-flushed toilet system would be relatively small, needing only

a small room in the existing site. The composting toilet, on the other hand, needs a larger

space with the inclusion of the storage tanks and an access area so that the by-product can

be reached. While option does not need a huge amount of space, it is still a larger footprint

than the alternate option (Table 16).

Using Google Maps, the area taken up by the building containing the Living Machine at

Findhorn is approximately 300m2. As seen in appendix 9.5, the Currumbin system contains a

number of buildings, with the entire plan taking up near 30 m2. The size of the CDM system

has not been stated in any studies, it has been noted that the MBR is contained within a

building (Sharma, et al., 2012), with wet wells and storage tanks outside of this (Sharma,

2012). As such the size would be approximately the same as that of Currumbin’s as they

share a similar design. Modelling the CH2 on available data, the two UF and single RO units

that closest resemble the flow rate calculated for this site is the RO 30.6.8 (Enviroconcepts)

and K16 respectively (Enviroconcepts 1) (Tables 14 & 15). This gives the size need to be

roughly 35.75m2. In the CH2 building, an entire floor was allocated for this (Othman &

Jayasuriya), so this value would seem reasonable (Table 16).


32

Table 14. Information about UF filters available from Enviroconcepts (Enviroconcepts)

Model No.

UF System Capacity

Membrane Elements

Line Sizes (mm) Approx. System

Dimensions (mm) Approx Weight

(Kg) LPM M3/hr Inlet Product Reject Length Depth Height

RO 4.2.8 50 3 4 50 38 38 3500 1100 1900 600

RO 9.3.8 80 5 9 50 38 38 4000 1100 1900 900

RO 15.3.8

160 10 15 80 50 50 4000 1100 2000 1200

RO 30.6.8

330 20 30 100 80 50 5500 1500 2000 1800

RO 40.8.8

500 30 40 100 80 50 7000 1500 2200 2500

RO 55.11.8

660 40 55 150 100 80 Custom Custom Custom 3300

RO 70.14.18


RO 140.28.8


Table 15. Information on RO filters available from Enviroconcepts (Enviroconcepts 1)

Model No.

UF System Capacity

Membrane Elements

Line Sizes (mm) Approx. System Dimensions (mm)

Approx Weight

(Kg) LPM M3/hr Inlet Product Reject Length Depth Height

K2 50 3 2 50 50 50 900 790 2300 200

K4 80 5 4 50 80 100 1300 790 2300 300

K8 160 10 8 50 80 100 2600 1250 2260 700

K16 330 20 16 80 100 150 4000 1250 2260 1200

K24 500 30 24 80 100 150 4300 1250 2260 1800

K30 660 40 3040 100 100 150 4600 1250 2260 2200

K40 830 50 50 100 100 150 5400 1250 2340 2800

K80 1600 100 100 100 100 150 10800 1400 2340 4000

Table 16. Comparison of options for footprint criterion

Preferred options: Footprint



Rainwater flushed

Composting Currumbin CDM CH2 Findhorn

5.3 Complexity

As the complexity of the system increases so does the pressure on staff and the RIA itself for

training, maintenance and education. As this is undesirable additional work, the simpler


33

equipment is preferred. In regards to the water source, the higher number of interacting

systems increases the complexity of the overall project having to balance various inputs and

outputs; this suggests that combination of the sources would be considered more complex

compared to a single option (Table 17).

The composting toilet keeps the collected waste in the tank; this is undesirable compared to

the alternate method due to the treatment and the upkeep needed for the production of

fertiliser from the waste (Table 17). A further drawback to this method is the handling of the

waste, this waste needs to be treated to a set standard to be used and the handling of it

may cause some health hazards to those administering it if not managed properly (Anand &

Apul, 2011).

Maintenance required for the Findhorn method is rather low, needing to dispose of the

collected sludge one every 4-5 years (Laylin, 2010), while the sludge formed from the textile

filter needs to be removed every 8-10 years (Advantex). The CH2 model needs constant

cleaning of the RO filters, this is done through a building management system to minimise

human interaction (Hes & Cummings) with monitoring for fouling is conducted every 14

days (Othman & Jayasuriya). Maintenance of the CDM system consists of 6 monthly

chemical cleaning of the MBR (Sharma, et al., 2012), and a fortnightly removal of the excess

activated sludge (Chong, Ho, Gardner, Sharma, & Hood, 2011) (Table 17).

Table 17. Comparison of options for complexity criterion

Preferred options: Complexity



Rainwater flushed

Composting Currumbin Findhorn CH2 CDM

5.4 Education potential

As one of the goals of this expansion is to provide education to tourists and visitors

concerning environmental sustainability, it will be important that the final system provides

something for guests to consider. With this in mind having both the technologies together

would provide a good visual comparison and better opportunity for education (Table 18).

The compare and contrast technique is a commonly used method of education and the site

would benefit from such a proven method that could be utilised with this combination

(Chin, Chi, & Schwartz, 2016).

Both the toilet options would support this criterion by showing an alternative from the

commonly used toilet system, the composting toilet also has the additional educational

component of turning the waste into a useable byproduct, giving it the edge in this criterion

(Table 18). A common barrier to the acceptance of composting technology is the lack of


34

awareness, so by having this addition to the centre would alleviate the negative stigma on

this environmental technology (Anand & Apul, 2014).

The Findhorn model would allow for the most interactive education for the water

treatment, having a walk through greenhouse as in the Findhorn ecovillage, would allow the

public to view close up the methods of treatment. The remaining three options have their

parts hidden away with the exception of the textile filter that can be opened and viewed

(Table 18). There is a way that the hidden methods could be adapted for education

purposes as has been done at Perth’s Central Institute of Technology’s green skills building,

where the water treatment system is situated in a glass-walled room allowing people to see

the components inside (Figure 9).

Figure 9. Image of water treatment facility at the Green Skills Building

Table 18. Comparison of options for education criterion

Preferred options: Education


Rainwater and desalination

Desalination Composting Rainwater flushed

Findhorn Currumbin CDM CH2

5.5 Environmental Factors

OPL’s sustainable water target outlines the want to supply water to buildings efficiently

(Bioregional, 2015), this would suggest that the reuse of greywater would suit this criterion


35

as it reuses water, and although this principle would provide no preference to either of the

other options, the land use and wildlife subsection aims to protect and restore natural

habitats, signifying that the desalination option through impacting the local environment

would be unsuited with supporting proof from the existing salt intrusion issues (Rottnest

Island 1, 2014). In regards to Earthcheck, all three sources, Desalination, RWH and

greywater use are all listed as suggested alternatives to a potable water source, it is

acknowledged that desalination is an energy intensive method and that storage of rainwater

may be a more beneficial option due to this environmental impact (Earthcheck research

institute, 2014), from these two guidelines the preferred option would be the combined

RWH and desalination (Table 19).

The reclaimed water flushed system rates scores lowest here due to the use of water where

the composting option uses no water (Table 19). Additionally, the composting toilet

contains and treats its waste to produce a useable product, making this the most aligned

option to the RIA and other guidelines.

The consideration for the effluent models returns to the quality of water released into the

environment, as this is considered in section 5.8 it won’t be covered here to avoid being

rated on the same concern twice

Table 19. Comparison of options for environment criterion

Preferred options: Environment




- - - -

5.6 Public perception

In a study conducted by Hurliman and Dolnicar on the acceptance of water alternatives in

Australia, rainwater was indicated by participants to be the more well viewed option in

comparison to desalination, this was only by a small margin, where rainwater was only 3%

higher than that of desalination (Hurlimann & Dolnicar, 2010) (Table 20).

As the rain flush toilets are better known and similar to the commonly encountered waste

disposal method, there is a larger acceptance of this method over that of the composting

from the public (Anand & Apul, 2014). Although with the use of composting toilets already

on the island there is proof to the public that this method works providing confidence in this

method, nevertheless there are still some concerns regarding composting toilets from the

public and as such scores lower in the MCA (Table 20).

As there has been no study of public views comparing these wastewater treatment systems,

there is no point of comparison for this criterion.


36

Table 20. Comparison of options for public perception criterion

Preferred options: Public perception



Desalination Rainwater flushed

Composting - - - -

5.7 Availability of water

Availability refers to the readiness of water available for use through the year. The lakes and

aquifers are permanent features, with the availability of this water is constant year long.

Having two sources of water would be additionally beneficial over a single source increasing

the overall accessibility (Table 21). This is furthered by the addition of a greywater system

alongside the rainwater system for use on non-potable uses, as this would lower the

reliance on the primary source and allow for a longer rationing of the water through the

year.

The choice of toilets gives an interesting comparison, the option of composting provides the

benefit of lowering overall water use, while it also removes the opportunity for the

production of a wastewater stream to be reused. The reasoning for making the composting

toilet the preferred option here was that although the alternate would provide some

wastewater source, a fraction of this will be unusable due to loss and as blackwater; the

composting toilet would rearrange the water flow of the system allowing water to be

available for an alternate source (Table 21).

The availability of water does not affect the output of water; all models considered can

successfully treat the modelled amount of waste water produced by the proposed

development.

Table 21. Comparison of options for availability criterion

Preferred options: Availability




- - - -

5.8 Water quality

The quality of both sources of water can be may be contaminated by pathogens and contain

dissolved solids (Argaw, 2001), there are measures that can be undertaken to improve the

water quality obtained from a RWH scheme (MWH, 2010). Therefore if the RWH source is

utilised as a primary source and desalination used as a reserve, this arrangement would

serve to be the better option (Table 22). The addition of greywater systems to the


37

combinations is beneficial to water use but due to strict protocols to its use, it needs to be

treated well increasing the difficulty to reach the appropriate standards (Department of

Health, 2010).

As the composting toilets do not use water, the inclusion of these in the system will not

reduce the quality of the water. The reclaimed water-flushed toilets, on the other hand,

introduce a blackwater stream into the system, increasing the contamination risk and

resulting in more treatment needed for the wastewater (Department of Health, 2011)

(Table 22).

CH2 system treats water to a 'class A' approval using the Queensland rating system (Othman

& Jayasuriya), while both Currumbin and CDM attain an A+ rating (Innoflow, 2009), (Sharma,

et al., 2012). The quality of effluent from the Findhorn living machine reported follows the

Queensland’s A+ approval for some of the categories, the number of virus and pathogens

within are not found (Table 22).

Table 22. Comparison of options for water quality criterion

Preferred options: Water quality




Currumbin CDM CH2 Findhorn

5.9 Life expectancy

The filters of the desalination system have a life expectancy of about five years before

replacement is needed (Mickley & Jordahl, 2011), while the rainwater option has a life

expectancy of 20-25 years on the tanks and 10 for the pump (MWH, 2010). In the combined

option there would be less strain on the desalination system, providing a longer life than if

the system was working unaccompanied (Table 23).

A report on the life cycle analysis of toilets gave composting toilets a 35 year lifetime, while

the associated pumps and filters had a life span of 20 and 5 years, respectively. This report

also included the life assessment of rainwater flushed toilets, and although the system still

uses pumps, it’s given lifespan was greater, or as long as the analysis, which was 50 years

(Anand & Apul, 2011) (Table 23).

The textile filter system as in Currumbin do not need replacement (Figure 21), the pumps

have an expected life of 20 years (Appendix 9.5), the membranes for CH2 model need

replacing every 4 years (De Groot, 2013). The MBR example at CDM has a life expectancy of

30 years (Sharma, et al., 2012). The Findhorn model uses gravity to move the water, and no

set life expectancy as the life forms used re-establish themselves (Table 23).


38

Table 23. Comparison of options for life expectancy criterion

Preferred options: Life Expectancy



Desalination Rainwater flushed

Composting Findhorn

CDM Currumbin CH2

5.10 Aesthetics

The water sources do not have much of an impact regarding the aesthetics of the system,

however there is the need for mosquito breeding precautions for long term storage of

water. This will be more of an issue with the rainwater option due to the need for longer

storage (Table 24).

There is a perception that the composting toilet would have odour and maintenance issues,

this is true for both, the odour aspect is amended by the installation of exhaust fans (Anand

& Apul, 2014). Even with this, there is still the building itself, these can be made to be

visually pleasing at the cost of space, as the toilets need to be constructed in a separate

building, impacting on the visual aesthetics (Table 24).

The living machine provides a visually appealing option, with the plant life supporting the

environmental solution it gives, it does produce some odours the plant's will aid in masking

this. Depending on preference the textile filters can be constructed above or below ground

(Former to limit ground disturbance and the latter to remove visual disturbance), this

method does produce odour the systems are designed with activated carbon filters to

minimise disturbance (Innoflow, 2009). The CDM method brings with it both odour and a

visual issue that has been amended by containing the facility within a building, the odour,

however, has been captured and recycled through diffusers and reused as an aeration

source, limiting this output (Sharma, et al., 2012). The odour and noise from the CH2 system

has been of concern and to comply with regulations has been placed in the sub-basement to

minimise odour and noise issues (Hes & Cummings), this could be a hindrance for the

proposed site (Table 24).

Table 24. Comparison of options for aesthetics criterion

Preferred options: Aesthetics



Rainwater flushed

Composting Findhorn Currumbin CDM CH2


39

5.11 MCA summary

The previous rankings have been compiled together for each of the 14 options (Table 12)

and totalled into a MCA (Table 25). Here the lower number is the preferred option. The

weighting was taken through a questionnaire filled by visitors to the island and

representatives on the island (Figure 10, Appendix 9.6). This was to find the importance of

each criterion to the stakeholders. To maintain a balance between the two sources; an

average was taken from each source before finding a combined average. This weighting was

used to multiply the scores to find a final value that would be used as the overall score for

the option (Communities and local governments, 2009).

Table 25. MCA rating summary of all 14 combinations with weighted total

Op

tion

Co

st

Foo

tprin

t

Co

mp

lexity

Edu

cation

Enviro

nm

ent

Pu

blic

percep

tion

Availab

ility of

water

Water q

uality

Life expectan

cy

Aesth

etics

Total

Total w

ith

we

ightin

g

Weighting 3.9 5.0 8.5 7.4 1.6 7.9 3.8 4.4 5.4 7.3

1 6 6 4 5 4 3 4 8 4 3 47 248.4

2 7 7 5 4 3 2 3 7 3 4 45 242.6

3 4 3 3 6 4 3 4 5 6 4 42 229.4

4 5 4 4 5 3 2 3 4 5 5 40 223.6

5 5 3 6 7 4 3 4 5 5 5 47 268.1

6 6 4 7 6 3 2 3 4 4 6 45 262.3

7 5 7 5 4 3 4 3 7 4 4 46 256

8 6 8 6 3 2 3 2 6 3 5 44 250.2

9 3 4 4 5 3 4 3 4 6 5 41 237

10 4 5 5 4 2 3 2 3 5 6 39 231.2

11 4 4 7 6 3 4 3 4 5 6 46 275.7

12 5 5 8 5 2 3 2 3 4 7 44 269.9

13 6 6 6 6 3 4 3 6 7 7 54 311.9

14 7 7 7 5 2 3 2 5 6 8 52 306.1


40

Figure 10. Average results of questionnaire, where lower value is considered more important

0

2

4

6

8

10

12

Ave

rage

Sco

re

Criteria

Average of Scores Relating to Concerns on Criteria for Proposed Water System

Staff Average

VisitorAverage

CombinedAverage


41

6. Results

Figure 11. Resulting weighted scores of 14 water system options

From the results in figure 11, it can be seen that the best (Lowest) scoring options are 4, 3,

10 and 9. Notable about these four is that they all use the Currumbin textile filter design for

effluent treatment, 4 and 10 have the combined RWH and desalination as the source while

4 and 3 both have reclaimed water-flushed toilets. The options with CH2 as the treatment

method were dominated by the other options; consistently scoring lower than the other

options (Communities and local governments, 2009).

Therefore, from these results, the final preferred option is the combined RWH and

desalination, reclaimed water-flushed toilets with the Currumbin model for treatment.

Although with the concern about drying climate affecting the island (Rottnest Island

Authority, 2014), the third option would also be worth considering, that being RWH and

desalination with composting toilet and the Currumbin model, lowering the water use still

through a waterless toilet.

6.1 Sensitivity analysis To ensure the final decision that option 4 is the preferred choice, a sensitivity analysis was

performed (Communities and local governments, 2009). To do this the final scores were tallied

excluding a single criterion to see the influence it had on each option, the results of this analysis is

provided in figure 12. The results show that not only is option 4 the better (Lower) scoring in the

overall results, but also in seven of the ten analyses. The categories where option 4 was lacking are

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

We

igh

ted

sco

re

Option number

Weighted MCA results of water systems


42

public perception where option 4 is the third ranked and had placed second in both complexity and

education (figure 12). This shows that option 4 is confidently the preferred choice for the final water

system.


43

Figure 12. Assessment of sensitivity for criteria’s effect on options scores


44

6.2 Final design

Figure 13 shows the final design concept for the system following the MCA results.

Figure 13. Final system flow model

The RWH system includes a first flush diversion system to minimise pollutants (Australian

Government, 2008), before the water arrives at the shared sedimentary, filtration and UV

treatment for the three water sources (NSW government Health).

The greywater system would be a greywater treatment system (GTS) as this would allow

reuse with toilets, laundry or surface drip irrigation while the alternative greywater

diversion device only allows for subsurface irrigation (Department of Health, 2010). This

system would contain screening, filtration and disinfection as seen in figure 14 (EMRC,

2014). This treated water can be stored for 24 hours before reuse in non-potable sources

(Department of Health, 2014).


45

Figure 14. Model of greywater Treatment System (EMRC, 2014)

The waste water streams from the first flush system, potable and non-potable sources

proceed into the Currumbin model treatment system, following the settling tank, textile

filters, microfiltration system and disinfection through UV and chlorine dosing, the treated

water is returned to be reused in the non-potable sources.

This system will still produce waste that will need to be removed such as the solids caught at

the settling tanks and captured solids from the filtration systems. As this will not be suitable

for disposal to the environment this would need to be removed along with the solid wastes

from the island. This is a matter that could be a topic for future work as its method of

disposal or reuse would depend on the components present in the collected waste.

6.3 Guidelines & legislation

As the site will produce over 5000L/day of wastewater (Table 5), the system will need

approval from DOH and local government (Department of Health, 2011). As well as these

agreements, a nutrient and irrigation management plan from DEC (Department of Health,

2011) if the recycled water is to be used on the nursery plants, garden or released to the

surrounding environment (Department of Water, 2010).

The legislation regarding the quality of drinking water and use of recycled water outline

numerous monitoring and maintenance requirements that would need to be adapted to the

ongoing use of the site as well as a risk management plan for the water use on the site


46

(Natural Resource Management Ministerial Council, 2006). A summary of these is presented

in appendix 9.7.

6.4 Final cost & grants

A commercial sized greywater treatment system for this purpose would cost $74,000 and an

operating cost of $500 per year for maintenance and testing (EMRC, 2014). The rainwater

tank has rebates of $50 for installation and $600 for internal plumbing, while the cost for

purchase and installation of the RWH system in an existing building would be $3,700, and

$20 per year for operating and maintenance costs (Marsden Jacob Associates, 2009). The

SSF system costs an approximate $45,000 for the installation and parts (Ludwig, 2015), the

maintenance for this being $57.75 a year (Corral, et al., 2014).

These in addition to the approximate cost of the wastewater treatment system would give a

total of $209,910 for the initial purchase of the water system and an operating cost of

$577.75 per year. This would be assuming no cost from electricity with power sourced from

renewable technologies.

Using this information figure 15 shows the payback period will be 20 years comparing the

savings from water use as shown earlier in table 1, which shows a yearly saving of

$11540.74 by avoiding the water produced and treated through the island's infrastructure.

As 20 years is also the expected lifespan of the majority of the parts in this system (Textile

filters, pumps and GTS), this would have the system break even, as a comparative look the

payback period for the system without the GTS shows that it would drop to a 13 year

payback period, an option which may be more financially beneficial.

For a further comparison the two next preferred rated options have been calculated. Option

3 includes desalination, GTS, rainwater flushed toilets and the Currumbin treatment system.

This change reduces the payback period by less than a year giving no significant change

(Figure 15). Option 9 consists of desalination input, GTS, composting toilets and the textile

filter. This option increases the payback period to 24 years (Figure 15).


47

Figure 15. Estimated payback period for proposed water system

7. Conclusion Global warming and a drying climate is a driving factor in the development of the

sustainable design of buildings, this also is an important influence on the RIA’s management

of Rottnest Island and the improvement of the existing buildings. This work has given an

outline to find the best suited decentralised water system for the expansion of the Rottnest

Islands nursery.

This has been done through:

Modelling the current water use of the building and extrapolating this to find the

estimated use at the forthcoming development resulted in a projected 2,737,500L

per year.

A Matlab program was compiled to calculate the input of water available from

arrangements including rainwater, drainage and solar powered pumps for

groundwater. This gave the outcome that rain and drainage catchment were not

sufficient sources of water alone, only options that included desalination of

groundwater were able to supply enough water.

A revision and comparison of the options available for water sources, toilets and

waste water treatment through a weighted MCA table resulted in finding the best-

suited option was a combined RWH and SSF desalination for a water source,

greywater for non-potable uses such as toilet flushing. Wastewater treatment would

-250000

-200000

-150000

-100000

-50000

0

50000

100000

150000

1 3 5 7 9 11 13 15 17 19 21 23 25

Co

st (

$)

Years from installation

Payback Period for Water System

Option 4

Option 4 without GTS

Option 3

Option 9


48

be modelled after the Currumbin eco-village, using septic tanks, textile filters and

microfiltration before UV and chlorine dosing for residual treatment. This system

would have a payback period of 20 years, which could be reduced to 13 with the

exclusion of the GTS.

This system has been represented through a flow diagram to illustrate the

concluding decision of system.

As the flow meters will be installed after completion of this report it is recommended that

the calculated flow of water is confirmed before continuation of work. The next step for this

would be to examine this using a small scale system before implementation. Furthermore,

there is the issue of the produced waste; this will be hard to assume a method for disposal

due to the uncertainty of the composition. The power use by this system is another area of

study, as the entire site is aimed to be a standalone system; the systems source of electricity

could be combined from the entire site's source or aside from it working in an enclosed

arrangement.


49

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56

9. Appendix

9.1 Case studies

9.1.1 Ocracoke, USA

The barrier island village of Ocracoke, off the shores of North Carolina, has numerous

similarities with Rottnest Island, notably is that it has a relatively small permanent resident

number with tourism increasing the numbers on the island throughout the summer period

(Pompeii, 2016). This island, being susceptible to climate change has a high interest in water

safety, with consideration of the natural environment. Since 2011 the island uses a reverse

osmosis plant to provide the island's water needs, with the water demand and price rising,

the need for an alternate source is necessitated.

The sewer system and stormwater is also below expectant quality, with residents worried

about standing waters due to poor soil drainage, its facilitation of mosquito breeding, and

the high results of E.coli found in water testing (Pompeii, 2016), an issue caused by long-

standing problems with dated septic tanks, where the septic system here has been

contaminating the shallow unconfined aquifer (Pompeii, 2014).

With the effects of increasing land use has on the natural processes of the land, more work

is being put into understanding the hydrology and aquifer characteristics. Noted changes

that have been discussed include reorganising the housing types and density as to avoid

blocking runoff to areas that would benefit from it and to limit future development. Past

methods of water use on the island have also been revisited, with renewed interest in

houses using cisterns to store collected water (Pompeii, 2014).

9.1.2 The Grove, Peppermint Grove

The grove is a combined library, community centre and council office located in the shire of

Peppermint grove, Western Australia (EMRC, 2011). This system includes a rainwater

catchment system and on-site wastewater as well as another climate sensitive design. The

RWH system is designed to accommodate 100% of the internal water use through roof

catchment of the building and below ground water storage; this is reported to lower mains

water consumption by 730 kL per year (Shire Peppermint Grove).

This system is complicated in that it involves source separation for storage and separate

treatment for each wastewater stream for greywater (Figure 16), brown water and yellow

water. Here the greywater is a treated with a sedimentation tank and ozonation before

being sent to the landscape for subsurface irrigation (Shire Peppermint Grove). The brown

water is sent to an aerobic treatment module, this is preceded by a biogrinder and a pair

filters, the former maintains flow rate below the maximum capacity of the treatment tank,

sending any overflow to the sewer (Shire Peppermint Grove), the Biolytix pod is a layered

system that uses micro and macro organisms to break down the waste fed in such as worms

and bacteria. This system has a low maintenance schedule of one service per year as the


57

produced hummus acts as part of the filter and the worms self-replenish (Biolytix, 2015).

The yellow water utilises separation through the use of waterless urinals and urine diverting

pan toilets, this collected water is stored before treatment and use in the landscape (Shire

Peppermint Grove).

Figure 16. Schematic diagram of The Grove integrated water system (EMRC, 2011)

The cost for the wastewater treatment component of this project was $550,000 (EMRC,

2011). This system provides points of interaction available for education, one such example

is the metering at significant points, allowing for real-time volumes of water usage (Shire

Peppermint Grove).

9.2 Desalination options

POE = Point of entry

POU= Point of use

SSS = Small-scale system

NOM = Natural organic matter

Table 26. Options for small scale decentralised water treatment systems (Rajapakse, Waterman, Millar, & Sumanaweera, 2014)

Technology Suitability Pollutant

Roughing Filtration Pebble matrix filtration,

Up-flow Roughing Filtration, Horizontal Flow Roughing

POE SSS

Turbidity


58

Coagulation, filtration, chlorination

POU POE SSS

Low turbidity Pathogens

Moringa Oleifera POU POE SSS

Turbidity

Kanchan filters POU Arsenic Iron Low-turbidity Pathogens

Slow Sand Filters Granular Activated Carbon Sandwich Filtralite media (lightweight ceramic)

POE SSS

Low turbidity Pathogens Odour NOM

Rapid Sand Filters SSS Turbidity

Granular Activated Carbon POU POE SSS

Pesticides NOM

Membrane Filtration MF-0.1µm UF-0.01µm NF-0.001 µm RO-0.0001 µm

POE SSS

Low turbidity Pathogens NOM Salts

Ion Exchange POU POE SSS

Hardness Nitrates Arsenic

Electro Coagulation POE SSS

Hardness; Metals; Fluoride; Dyes; Organics; Phosphate; Algae; Bacteria

Catalytic Advanced Oxidation POE SSS

Organics Metals Metalloids


59

9.3 Contact with companies regarding waterless toilets

9.3.1 Ecoflo

Figure 17. Communication with Ecoflo regarding options for composting toilet

9.3.2 Dynamic supplies

Figure 18. Communication with Dynamic Supplies regarding options for composting toilet

9.3.3 Waterwally

Email sent with information attached for Clivus Multrum composting toilets.


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Figure 19. Part of communication with Waterwally regarding options for composting toilet

9.4 Complete list of combinations for water system

Table 27. Total 48 combinations of options for MCA

Option reference Input Greywater reuse Toilet Effluent model

1 Rain No reclaimed water flushed Findhorn

2 Desal No reclaimed water flushed Findhorn

3 Rain and Desal No reclaimed water flushed Findhorn

4 Rain Yes reclaimed water flushed Findhorn

5 Desal Yes reclaimed water flushed Findhorn

6 Rain and Desal Yes reclaimed water flushed Findhorn

7 Rain No reclaimed water flushed Currumbin

8 Desal No reclaimed water flushed Currumbin

9 Rain and Desal No reclaimed water flushed Currumbin

10 Rain Yes reclaimed water flushed Currumbin

11 Desal Yes reclaimed water flushed Currumbin

12 Rain and Desal Yes reclaimed water flushed Currumbin

13 Rain No reclaimed water flushed Capo di Monte

14 Desal No reclaimed water flushed Capo di Monte

15 Rain and Desal No reclaimed water flushed Capo di Monte

16 Rain Yes reclaimed water flushed Capo di Monte

17 Desal Yes reclaimed water flushed Capo di Monte

18 Rain and Desal Yes reclaimed water flushed Capo di Monte

19 Rain No reclaimed water flushed CH2

20 Desal No reclaimed water flushed CH2

21 Rain and Desal No reclaimed water flushed CH2

22 Rain Yes reclaimed water flushed CH2

23 Desal Yes reclaimed water flushed CH2

24 Rain and Desal Yes reclaimed water flushed CH2

25 Rain No Composting Findhorn

26 Desal No Composting Findhorn


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27 Rain and Desal No Composting Findhorn

28 Rain Yes Composting Findhorn

29 Desal Yes Composting Findhorn

30 Rain and Desal Yes Composting Findhorn

31 Rain No Composting Currumbin

32 Desal No Composting Currumbin

33 Rain and Desal No Composting Currumbin

34 Rain Yes Composting Currumbin

35 Desal Yes Composting Currumbin

36 Rain and Desal Yes Composting Currumbin

37 Rain No Composting Capo di Monte

38 Desal No Composting Capo di Monte

39 Rain and Desal No Composting Capo di Monte

40 Rain Yes Composting Capo di Monte

41 Desal Yes Composting Capo di Monte

42 Rain and Desal Yes Composting Capo di Monte

43 Rain No Composting CH2

44 Desal No Composting CH2

45 Rain and Desal No Composting CH2

46 Rain Yes Composting CH2

47 Desal Yes Composting CH2

48 Rain and Desal Yes Composting CH2


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9.5 Contact with Orenco

Figure 20. Cost estimation of Advantex treatment system


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Figure 21. Energy use estimation of Advantex treatment system


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Figure 22. Example of treatment system using advantex textile filters

Figure 23. Notes regarding features of Advantex treatment system


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9.6 Results from questionnaire Table 28. Results of questionnaire for weighting of MCA criteria

Criteria Description Visitors RIA staff Cost Initial capital and operating

costs

3, 4, 7, 5 2, 4, 1, 4, 4

Footprint Physical size of system. How

much space it will take up

9, 2, 4, 2 3, 2, 8, 8, 8

Complexity More complex machines

mean higher maintenance

and more training for staff

8, 10, 10, 8 10, 9, 7, 7, 7

Education Visibility and opportunity to

use as a teaching device

5, 9, 5, 9 7, 7, 10, 6, 9

Environmental impact Any negative impacts on

environment. In line with

targets set by RIA, OPL and

Earthcheck

1, 1, 1, 1 1, 1, 3, 5, 1

Public acceptance How public views certain

technology

10, 8, 9, 10 5, 6, 2, 10, 10

Availability of water Yearlong or Intermittent

water availability

4, 3, 2, 6 4, 3, 9, 1, 2

Water quality Affects amount of treatment

needed before use and before

disposal

2, 5, 3, 3 8, 10, 5, 2, 3

Life expectancy Reliability of parts and

system as a whole

7, 6, 8, 4 6, 5, 4, 3, 5

Odour/Noise/Visual

disturbances

Any perceived negative

impacts

6, 7, 6, 7 9, 8, 6, 9, 6

9.7 Maintenance, monitoring and approvals

9.7.1 Rainwater

For rainwater systems, the prominent sources of contamination are birds, small animals and

debris from the roof catchment. To minimize this contamination there would need to be

leaf screen filters and a first flush diverter incorporated into the design before reaching the

storage unit (Dupont & Shackel, Rainwater, 2013), furthermore general maintenance such

as gutter cleaning and removal of overhanging branches aid in the reduction of debris

entering the system (Australian Government, 2011), and the addition of disinfection and

filtration systems methods reduce the microorganisms present (NSW government Health).

The water testing of rainwater should only be needed in in exceptional circumstances

(Australian Government, 2004). Table 29 provides regular maintenance checks as outlined

by the Australian government (Australian Government, 2004)


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Table 29. Maintenance schedule for rainwater harvesting system

Time Action

6 monthly Maintenance of tank. Removal of overhanging branches and check of access covers

6 monthly Check tank for signs of larvae and insects. Repair screening and treat as necessary

6 monthly Check roof catchment area for any uncoated flashing that needs covering

6 monthly Clean gutters and inlet filters

2-3 years Remove collected sediment in the water tank. Clean and disinfect tank of required

6 monthly Check function of first flush system (Australian Government, 2008)

Figure 24 outline the necessary approvals and regulations for the installation and running of

a rainwater system, these need to be adhered to as well as any local government needs

(Australian Government, 2008).


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Figure 24. Approvals for installation of rainwater systems (Australian Government, 2008)

9.7.2 Recycled water

If the greywater treatment device is to be used for indoor use (Toilet flushing and washing

machine), then it needs to provide advanced secondary treatment and disinfection to reach

the 10/10/1 standard. This describes a water quality of <10mg/L BOD, <10mg/L suspended

solids and <1 E.coli/100mL, <1pfu/100mL coliphages, and <1cfu/100mL clostridia

(Department of Health, 2010).


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An approved system needs yearly inspection by an authorised service person that will

provide a service report to local government (Department of Health, 2010).

The approval of a GTS must be approved by DoH, local government and be installed by a

licenced plumber (Figure 25), the approval may contain specific maintenance requirements

in these approvals and need to be adhered to (Department of Health, 2010). Furthermore,

these installations need to be notably distinguishable from potable water through the use of

purple piping and signage (Department of Health, 2010).

Figure 25. Steps to aquire approval of GTS


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9.7.3 Monitoring

Monitoring of the recycled water is needed to ensure that the water system has achieved

compliance with the requirements of the regulations (Natural Resource Management

Ministerial Council, 2006). Table 29 outlines sampling frequency’s for various system

operations, the appropriateness of these would be distinguished through a risk

management strategy and requirements given by the DoH (Natural Resource Management

Ministerial Council, 2006).

The national Water Quality Management Strategy also outlines water quality objectives for the use of recycled water. For the proposed purpose this would require BOD <20 mg/L, SS <30 mg/ L, Disinfectant residual (eg minimum chlorine residual) or UV dose, and E. coli <100 cfu/100 mL (Natural Resource Management Ministerial Council, 2006). For the water source, it is recommended that there is to be one sample per week per monitoring zone; this will be to review limits of factors outlined by the DoH (Australian Government, 2011).

9.8 Matlab model

%Combined Water capture for Rain harvesting, Drainage capture and Pumping

using solar power %Aled Lewis. 2016.

%This program references an excel worksheet titles masterdata.xlsx for data

on the average %rainfall of 2015 and average solar availability for Rottnest island on

sheets in %that order entitled rainfall 2015 and solar availabilty average.

%This program can be adapted for other locations and use data from other %years with the alteration of this data source.

%Reset variables clc; clear; captured_rain = 0; captured_drainage = 0; captured_pump = 0; days_rain = 0; days_drainage = 0; days_pumped = 0; daysbelowzero = 0; stored_water = 0;

%Aquire data from master data sheet

%Rain data Rdata = xlsread('Masterdata.xlsx', 'Rainfall 2015');


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%Solar data Sdata = xlsread('Masterdata.xlsx', 'Solar availability average'); %Convert MJ to kWh Sdata = Sdata/3.6;

%% Start with rainfall data

%Data for Rain Catchment prompt = 'What is the designated rainwater catchment area in m2? '; area_rain = input(prompt); while area_rain <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the area in m2? '; area_rain = input(prompt); end fprintf('\n');

prompt = 'What percentage of the rainfall is available? '; disp ('Availability for common catchment material: Gravel ~60%, Concrete

~90%, Rooftop ~80%') available_catchment = input(prompt); while (0 >= available_catchment) || (available_catchment > 100) fprintf('Please enter a number between zero and one hundred'); fprintf('\n'); prompt = 'What percentage of the rainfall is available? '; available_catchment = input(prompt); end available_catchment = available_catchment/100; fprintf('\n');

%% Drainage data prompt = 'Is there drainage catchment at the site also? (1 for Yes, 0 for

No) '; drainage_YN = input(prompt); fprintf('\n');

%Calculating Drainage addition if drainage_YN == 1

%Area from which drainage is captured prompt = 'What size is the area with captured drainage, in m2? '; area_drainage = input(prompt); while area_drainage <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the area in m2? '; area_drainage = input(prompt); end fprintf('\n');

%Find % available from drainage prompt = 'What percentage of the drainage is available? '; disp ('Availability for common material: Gravel ~60%, Concrete ~90%,

Rooftop ~80%') available_drainage = input(prompt); while (0 >= available_drainage) || (available_drainage > 100)


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fprintf('Please enter a number between zero and one hundred'); fprintf('\n'); prompt = 'What percentage of the rainfall is available? '; available_drainage = input(prompt); end available_drainage = available_drainage/100; fprintf('\n');

%Irrigations input to drainage prompt = 'What is the flowrate of sprinkler heads in L/minute? '; irrigation_flowrate = input(prompt); while irrigation_flowrate <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the flowrate of sprinkler heads in L/minute?

'; irrigation_flowrate = input(prompt); end fprintf('\n');

prompt = 'How long, in minutes per day, do the sprinklers operate? '; irrigation_time = input(prompt); while irrigation_time <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'How long, in minutes per day, do the sprinklers

operate? '; irrigation_time = input(prompt); end fprintf('\n');

irrigation_input = irrigation_time * irrigation_flowrate *365 / 1000;

end %% End of drainage

%% Solar pump input prompt = 'Will there be solar powered pumping? (1 for Yes, 0 for No) '; pump_YN = input(prompt); fprintf('\n');

if pump_YN == 1

%Data for panels fprintf('Data for Solar Panels used') fprintf('\n'); prompt = 'What is the individual solar panel size in m2? '; area_panel = input(prompt); while area_panel <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the solar panel size in m2? '; area_panel = input(prompt); end fprintf('\n');

prompt = 'How many panels are there? ';


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number_panel = input(prompt); while number_panel <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'How many panels are there? '; number_panel = input(prompt); end fprintf('\n');

prompt = 'What is the panels efficiency at STC, as a percentage? '; efficiency_panel = input(prompt); while (0 >= efficiency_panel) || (efficiency_panel > 100) fprintf('Please enter a number between zero and one hundred'); fprintf('\n'); prompt = 'What is the panels efficiency at STC, as a percentage? '; efficiency_panel = input(prompt); end efficiency_panel = efficiency_panel / 100; fprintf('\n');

prompt = 'What is the performance ratio of the panel, between 0.5 and

0.9? '; performance_panel = input(prompt); while (0.5>performance_panel) || (performance_panel>0.9) fprintf('Please enter a number between 0.5 and 0.9'); fprintf('\n'); prompt = 'What is the performance ratio of the panel, between 0.5

and 0.9? '; performance_panel = input(prompt); end fprintf('\n');

%Finding the kWh produced by the solar panels with the inputed

limitations kWh = Sdata * efficiency_panel * number_panel * performance_panel *

area_panel;

%Data for pump fprintf('Data for Pump') fprintf('\n'); prompt = 'What is the power use of the pump, in kW? '; power_pump = input(prompt); while power_pump <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the power use of the pump, in kW? '; power_pump = input(prompt); end fprintf('\n');

prompt = 'How many pumps? '; number_pump = input(prompt); while number_pump <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'How many pumps '; number_pump = input(prompt); end


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fprintf('\n');

prompt = 'What is the pumps efficiency, as a percentage? '; efficiency_pump = input(prompt); while (0 >= efficiency_pump) || (efficiency_pump > 100) fprintf('Please enter a number between zero and one hundred'); fprintf('\n'); prompt = 'What is the pumps efficiency, as a percentage? '; efficiency_pump = input(prompt); end efficiency_pump = efficiency_pump / 100; fprintf('\n');

prompt = 'What is the flow rate in L/minute? '; flowrate_pump = input(prompt); while flowrate_pump <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the flow rate in L/minute? '; flowrate_pump = input(prompt); end fprintf('\n');

%Calculating water available to be pumped with available solar power pumped_water = kWh / power_pump * 60 * flowrate_pump * number_pump *

efficiency_pump;

end %% End of pumping calculations

%% Data for use and storage fprintf('Data for Site') fprintf('\n'); prompt = 'What is the water tank size, in L? '; tank_size = input(prompt); while tank_size <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the water tank size, in L? '; tank_size = input(prompt); end fprintf('\n');

prompt = 'What is average daily water use in L? '; water_use = input(prompt); while water_use <= 0 fprintf('Please enter a number greater than zero'); fprintf('\n'); prompt = 'What is the average daily water use in L? '; water_use = input(prompt); end fprintf('\n'); %% end of use and storage

%% Calculating water stored through year if drainage_YN == 1


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if pump_YN == 1

%Pumped + drainage + rain for col = 1:12; for row = 1:31;

days_rain = (Rdata(row,col) * available_catchment *

area_rain); captured_rain = captured_rain + days_rain;

days_drainage = ((Rdata(row,col) * area_drainage)*

available_drainage) + ((irrigation_input) * available_drainage); captured_drainage = captured_drainage + days_drainage;

days_pumped = pumped_water(row,col); captured_pump = captured_pump + days_pumped;

if days_rain + days_drainage + days_pumped > water_use stored_water = stored_water + (days_rain +

days_drainage + days_pumped - water_use);

if stored_water > tank_size stored_water = tank_size; end

else stored_water = stored_water - (water_use - days_rain -

days_drainage - days_pumped);

if stored_water < 0 stored_water = 0; daysbelowzero = daysbelowzero +1; end end end end

%Drainage + rain else

for col = 1:12; for row = 1:31; days_rain = (Rdata(row,col) * available_catchment *


days_drainage = ((Rdata(row,col) * area_drainage)*

available_drainage) + ((irrigation_input) * available_drainage); captured_drainage = captured_drainage + days_drainage /

1000;

if days_rain + days_drainage > water_use stored_water = stored_water + (days_rain +

days_drainage - water_use);



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else stored_water = stored_water - (water_use -

days_rain - days_drainage);

if stored_water < 0 stored_water = 0; daysbelowzero = daysbelowzero +1; end end end end

end

elseif pump_YN == 1

for col = 1:12; for row = 1:31; days_rain = (Rdata(row,col) * available_catchment * area_rain); captured_rain = captured_rain + days_rain;

days_pumped = pumped_water(row,col); captured_pump = captured_pump + days_pumped;

if days_rain + days_pumped > water_use stored_water = stored_water + (days_rain + days_pumped

- water_use);


else stored_water = stored_water - (water_use - days_rain -

days_pumped);

if stored_water < 0 stored_water = 0; daysbelowzero = daysbelowzero +1; end end end

end

%Rain only else

for col = 1:12; for row = 1:31;

days_rain = (Rdata(row,col) * available_catchment *


if days_rain > water_use stored_water = stored_water + (days_rain - water_use);


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else stored_water = stored_water - (water_use - days_rain);

if stored_water < 0 stored_water = 0; daysbelowzero = daysbelowzero +1; end end end end end

%% Finalizing equations if daysbelowzero > 365 daysbelowzero = 365; end

overflow = (captured_rain + captured_drainage + captured_pump -

stored_water - (water_use * 365)); if overflow < 0; overflow = 0; end

captured_rain = captured_rain/1000; captured_drainage/1000; format short g;

%% Final values clc fprintf('Total rainwater captured through the year(L):') disp (captured_rain) fprintf('Total drainage water captured through the year(L):') disp (captured_drainage/1000) fprintf('Total water available pumped through the year(kL):') disp (captured_pump/1000) fprintf('Total captured water available (kL):') disp ((captured_rain + captured_drainage + captured_pump) / 1000) fprintf('Total water used through year (kL):') disp (water_use * 365 / 1000) fprintf('Stored water at end of year (L):') disp (stored_water) fprintf('\n'); fprintf('Days without water stored:') disp (daysbelowzero) fprintf('\n'); fprintf('Water avalable above demand and storage') disp (overflow)

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