ecological sanitation: principles, technologies and project examples for sustainable wastewater and...

Ecological sanitation: Principles, technologies and project

examples for sustainable wastewater and excreta

management

C. Werner�, A. Panesar, S.B. Rud, C.U. Olt

Deutsche Gesellschaft fur Technische Zusammenarbeit (GTZ) GmbH, Sector Project Ecosan,

Dag-Hammarskjold-Weg 1-5, 65760 Eschborn

Tel. þ49 61 96 79 4220; Fax þ49 61 96 79 80 4220; email: [email protected]

Received 31 January 2008; revised accepted 15 May 2008

Abstract

In order to reach the UN Millennium Development Goals for significantly reducing the number of people without access to

adequate sanitation, new holistic concepts are needed, focusing on economically feasible closed-loop ecological sanitation sys-

tems rather than on expensive end-of-pipe technologies, thus enabling all countries to finance and maintain sustainable sanitary

systems. Such ecological sanitation systems advance a new philosophy of dealing with what to date has been considered as merely

waste and wastewater. They are based on the systematic implementation of the reuse and recycling of nutrients, organics and water

as a hygienically safe, closed-loop and holistic alternative to conventional solutions. Over the last few years an increasing number

of pilot and demonstration ecosan projects have been implemented worldwide. These have contributed to the further development

of a variety of ecosan technologies and operating and reuse options and have provided a large amount of experience with this new,

holistic approach. In the following, the principles of ecological sanitation are presented, an overview on the range of ecosan tech-

nologies is given and several successful ecological sanitation projects are described.

Keywords: Ecosan; Sustainability; Best practices; Project examples; Reuse

1. Introduction

Current conventional approaches to wastewater

management and sanitation fall under the category of

either waterborne or dry systems. In both cases the sys-

tem design is based on the premise that excreta is a

waste, and that waste should be disposed. It also

assumes that the environment can safely assimilate this

waste. Unfortunately, many years of experience have

shown that such conventional approaches are unable

to make a significant impact on the sanitary backlog

of nearly half of the world’s population, and even in

cases where conventional approaches have succeeded

in providing a functioning sanitary system; their

long-term sustainability is questionable, as is their� Corresponding author.

Presented at the Water and Sanitation in International Development and Disaster Relief (WSIDDR) International

Workshop Edinburgh, Scotland, UK, 28–30 May 2008.

Desalination 248 (2009) 392–401

0011-9164/09/$– See front matter © 2009 Published by Elsevier B.V.doi:10.1016/j.desal.2008.05.080

appropriateness to address the MDGs. The main disad-

vantages of conventional approaches to sanitation can

be seen in Fig. 1.

The main disadvantages of current, conventional

approaches to sanitation are as follows, also showed

in Fig. 1.

• Unsatisfactory purification or uncontrolled dis-

charge of more than 90% of wastewater worldwide

• Pollution of water bodies by nutrients, hazardous sub-

stances, pathogens, pharmaceutics, hormones, etc.

• Severe environmental damage and eutrophication of

the water cycle

Fig. 1. The main disadvantages of current, conventional approaches to sanitation (source: GTZ).

C. Werner et al. / Desalination 248 (2009) 392–401 393

• Consumption of precious water for transport of

waste

• High investment, energy, operating and maintenance

costs

• Frequent subsidisation of prosperous areas, and

neglect of poor settlements

• Loss of valuable nutrients and trace elements con-

tained in excrement through their discharge into

water bodies

• Predominance of combined central systems, result-

ing in problems with contaminated sewage sludge

The modern misconception that human excreta are

wastes with no useful purpose has resulted in the end-

of-pipe sanitary systems that we have today. In nature

however, there is no waste. All products of living

things are used as raw materials by others as part of a

cycle. Considering the environmental damage, the

health risks, and the worsening water crisis, resulting

from our present sanitary practices, a revolutionary

rethink is urgently needed if we are to correct this mis-

conception and realistically have a chance of achieving

the Millennium Development Goals of providing sus-

tainable sanitary services to over 1.2 billion people.

A new paradigm is required in sanitation, based on eco-

system approaches and the closure of material flow

cycles rather than on linear, expensive and energy

intensive technologies. This paradigm must recognise

human excreta and water from households not as a

waste but as a resource that should be made available

for reuse [6].

2. Principles of ecosan

Ecological sanitation is based on an overall view of

material flows as part of an ecologically and economic-

ally sustainable wastewater management system tai-

lored to the needs of the users and to the respective

local conditions. It does not favour a specific sanitation

technology, but is rather a new philosophy in handling

substances that have so far been seen simply as waste-

water and water-carried waste for disposal. Ecological

sanitation introduces the concept of sustainability and

integrated, ecosystem oriented water and natural

resources management to sanitation.

The basic principle of ecosan is to close the nutrient

loop between sanitation and agriculture with the objec-

tives shown in Fig. 2. The advantages are as follows:

• Improvement of health by minimising the introduc-

tion of pathogens from human excrement into the

water cycle

• Promotion of recycling by safe, hygienic recovery

and use of nutrients, organics, water and energy

• Conservation of resources (lower water consump-

tion, chemical fertiliser substitution, minimal water

pollution)

• Preference for modular, decentralised partial-flow

systems for more appropriate cost-efficient solutions

• Possibility to integrate on-plot systems into houses,

increasing user comfort, and security for women and

girls

• Contribution to the preservation of soil fertility

• Promotion of a holistic, interdisciplinary approach

(hygiene, water supply and sanitation, resource con-

servation, environmental protection, urban planning,

agriculture, irrigation, food security, small-business

promotion)

Closing the loop enables the recovery of organics,

macro and micro nutrients, water, and energy con-

tained in household wastewater and organic waste and

their subsequent productive reuse – if necessary after

adequate treatment – mainly in agriculture, or for other

reuse options. An essential step in this cycle is the

appropriate treatment and handling of the materials

throughout the entire process, from collection to reuse,

ensuring a series of barriers are erected that will reduce

the risk of disease transmission within acceptable lim-

its, thus providing comprehensive protection of human

health [6].

3. Ecosan technologies

As an integrated alternative, the implementation of

an ecosan project requires an interdisciplinary

approach that goes beyond the narrow disciplines and

technological aspects of domestic water supply and

wastewater management to address issues such as agri-

cultural use, sociological aspects of acceptance and

cultural appropriateness, health and hygiene, town

planning, economic and small-enterprise promotion,

institutional administration, and so on. Such an

approach also makes a large contribution to

the integrated management of water and other natural

resources.

394 C. Werner et al. / Desalination 248 (2009) 392–401

Ecological sanitation opens up a wider range of

sanitation options than those currently considered. To

optimise cost efficient, high quality treatment and recy-

cling options, two principles are very often applied in

ecosan systems:

Firstly, flow streams with different characteristics,

such as faeces, urine and grey water (see Fig. 3), are

often collected separately. This allows the application

of specific treatment processes and optimises reuse.

Secondly, unnecessary dilution of the flow streams

is avoided, for example by using dry, low flush or

vacuum transport systems. This minimises the con-

sumption of valuable drinking water and produces high

concentrations of recyclables.

Fig. 2. The advantages of implementing ecological sanitation (source: GTZ).


Rainwater harvesting and the treatment of organic

domestic and garden wastes and of animal manure can

also be integrated into ecosan concepts. Such a separa-

tion of the flow streams also allows a better integration

of the solid waste management sector, where there is

already a great deal of experience in the logistics, treat-

ment and marketing of discarded resources. As an

example, the collection system of solid waste can be

adopted to the collection of urine and faeces as well

as experience in the field of marketing the recycled

products.

However, whilst often making treatment easier and

less expensive, the separate collection and treatment of

the flow stream is not a prerequisite in ecosan systems,

and ecological sanitation is also possible in centralised

and combined flow systems.

Ecosan systems strive for resource efficiency. In

reducing unnecessary water consumption and avoiding

the contamination of water bodies, ecosan systems can

have an impact on reducing the costs of raw water treat-

ment and drinking water supply. Additionally, the

recovery and agricultural use of the organics and nutri-

ents contained in wastewater improves soil structure

and fertility, increasing agricultural productivity and

thus contributing to food security. The recovery of

energy through the anaerobic digestion of faeces,

organic waste and animal manure may also represent

a significant step towards energy efficiency, providing

biogas for cooking or electricity generation [6]. Yet,

ecological sanitation systems are in many cases still far

from overall sustainability due to various reasons: Due

to the pilot character of many projects, the costs for

Fig. 3. Separation of wastewater streams and examples of possible ecosan treatment elements (source: GTZ).


introducing new innovative systems are often higher

compared to already established treatment system. In

addition, awareness raising campaigns and capacity

buiding measures for ecological sanitation have to be

provided frequently to overcome existing cultural con-

straints towards the usage of treated excreta and

wastewater.

4. Ecosan in practice

As ecological sanitation does not prescribe a parti-

cular technical solution, but rather tailors sanitary sys-

tems to fit the needs of social, economic and

environmental sustainability in a given context, a wide

range of technologies can, and currently are, being

used in ecological sanitation systems. These range

from quite simple low-tech systems to sophisticated

high-tech solutions. On the low-tech side, the use of

system components such as simple dehydration toilets

(either with or without urine separation) or composting

toilets is common. For such systems, faeces and urine

are most often collected and treated on site, with the

recyclates being used locally, although an organised

central collection and marketing of the recyclates is

also possible. High-tech components of ecosan sys-

tems include the use of vacuum technology to collect

either black or brown water centrally with reduced

water consumption, struvite precipitation for the recov-

ery of nutrients, and membrane technology for the

recovery of water for irrigation, industrial or domestic

purposes. All these components can be put together

with other treatment ecosan technologies, such as con-

structed wetlands, treatment ponds, anaerobic digesters

or soilisation basins for sludge treatment, to optimally

address the treatment and resource recovery needs in a

particular area. Ecosan systems are also of particular

interest for international development and disaster

relief. The fact that it is often possible to build them

with local ressources, the flood protection of, e.g. the

two chamber urine-diversion dehydration toilet com-

pared to other low-cost sanitation systems like pit

latrines and the ability to not only offer a first basic

option but an enduring system which can be up-

scaled and which can even produce benefits by the

recovery of water, energy and nutrients, all make eco-

logical sanitation methods highly interesting for sanita-

tion projects in disaster relief.

At present, pilot demonstration and up-scaling pro-

jects are being implemented with the support of the

GTZ-ecosan project in more than 40 countries, among

them countries affected by post-war conflicts or natural

disasters like Afghanistan, El Salvador, Eritrea and

Nepal [4]. The programme mainly lays the foundations

for projects by researching, preparing and elaborating a

financing concept as well as supporting the elaboration

of baseline-studies, feasibility studies and project pro-

posals which may be submitted to financing agencies

or investors.

4.1. Navsarjan primary schools project in Gujarat,

India

In 2005, Navsarjan Trust established three primary

schools in rural areas of Gujarat. Each school has a total

capacity of 210 pupils and comprises a sanitation

building including toilets, showers and washing

facilities.

A sanitation bloc has been designed to provide toi-

lets, showers, washing and laundry facilities to pupils

and staff, while allowing the recovery of urine, faeces

and water for productive purposes. The ecosan toilet

block comprises eight single-vault-urine-separation

dehydration toilets and four waterless urinals for the

male pupils and staff members. The toilets are operated

in batches to facilitate the harvest of the finished com-

post. That means that only four toilets are in use at the

same time and receive daily deposits until the dehydra-

tion chamber below the squatting slab is ‘‘full’’ (see

Fig. 4 for a backview of the toilet blocks including the

dehydration chambers). The toilet cabins of the

‘‘closed’’ toilets are then used as showers. Addition-

ally, a vertical flow filter treats greywater from bath-

rooms, washbasins and the laundry area. The new

bathrooms, greywater treatment system and reuse gar-

dens were inaugurated on August 10th, 2006.

The urine from the UD toilets and urinals is col-

lected in a container and reused as fertiliser. The anal

cleansing water from the toilets is infiltrated into a sub-

surface irrigation of ornamental flowers. Treated grey-

water is reused for irrigating the kitchen garden. The

alternative use of the cabins as toilet or shower helps

to reduce the interior space and therefore construction

costs [3].


This system offers a low-cost and enduring alterna-

tive to conventional basic sanitation methods and is

also applicable in disaster relief. In contrast to, e.g.

Ventilated Improved Pit Latrines, no hole has to be dug

avoiding on the one hand groundwater pollution by

infiltrating urine contaminated by feacal bacteria and

making the system resistant against flooding. Further-

more, food security of the users is improved by provid-

ing a natural fertiliser and soil conditioner which can be

used in local agriculture.

4.2. Model-project for constructed wetlands in Syria

The village of Haran Al-Awamied is located south

east of Damascus, Syria. The inhabitants are poor, with

farming being the main source of income. The use of

untreated wastewater from the existing gravity sewers

for irrigation was common. The specified purpose of

the GTZ-supported ecosan project in Haran Al-

Awamied was therefore to make the use of wastewater

for irrigation hygienically safe and to make best use of

its fertilising effect. At the same time this project was

intended as a model-project to adapt the technology

to local conditions and to allow for the replication of

the technology elsewhere in the country.

One result of the project was that the treatment

space required per person was drastically reduced in

comparison to European standards due the favourable

climatic conditions in Syria. The implemented

model-plant itself consists of bar screens and a sedi-

mentation tank as a pre-treatment, two reed beds to

treat the wastewater, and one reed bed for sludge humi-

fication. The treatment efficiency of the treatment sys-

tem is shown in Table 1. The treated water, about 300

m3/d is collected in a tank for storage, and is pumped

from the collection tank to the fields near the plant

when needed, with the distribution being organised

by the farmers.

The improved availability of irrigation water con-

taining valuable nutrients reduces farmer’s expenditure

on commercial fertilisers. It contributes to higher

yields in crop production, and increases the number

of harvests from one to several per year. The reed

plants of the constructed wetland are used for wicker

and roof materials. The treated sludge is used as soil

conditioner.

This project started operation in November 2000.

As the constructed wetland provides the residents with

this range of possibilities, they provide a great deal of

support to ensure its correct functioning. Other moti-

vating factors for choosing the reed beds as treatment

option were the low costs, easy construction and simple

operation and maintenance of the system.

The construction and operation of the pilot con-

structed wetland plant in Haran Al-Awamied has

opened the gates for new innovative methods of waste-

water treatment in Syria. Based on the success of the

Fig. 4. Faeces dehydration chambers of the sanitation

facility with ventilation pipes (source: ESF).

Table 1

Analysis of treatment efficiency of constructed wetland in

Haran-Al-Awamied, Syria, (source: GTZ)

Parameter Unit Inlet Outlet Efficiency (%)

COD mg/L 446 70 84

BOD5 mg/L 220 32 85

PO4-P mg/L 19.3 6.1 68


pilot plant the Syrian Government has decided to allo-

cate more resources to build constructed wetlands in

other regions of the country. The Ministry of Housing

and Construction (MHC) prepared the planning

documents for a program that would combine capacity

development at governorate level with investment in

about 20 additional plants [1].

4.3. EcoSanitation facility for Adrash Vidyaprakaash

Sanstha’s College at Kulgaon Badlapur, India

The ‘‘Adarsh Vidya Mandir School’’ is located in

Badlapur town, in Maharashtra’s Thane district, about

68 km from Mumbai. The school accommodates about

11,000 students attending Primary School, Secondary

School and Junior College or the ‘‘Adarsh Vidya-

prasarak Sanstha’s College of Arts & Commerce’’. The

city of Badlapur does not have a sewer system. So far,

the school therefore depends on conventional on-site

sanitation, consisting mainly of septic tanks followed

by infiltration.

Following some capacity building workshops orga-

nised by the Indian Water Works Association IWWA

in cooperation with GTZ, seecon and other partners,

the city of Badlapur and the Adarsh School have taken

the decision to refurbish the sanitation system of the

school towards ecological sanitation.

In August 2006, construction began for a sanitation

building for the three-storied College of Arts &

Commerce building with a total number of about

2700 students. The open ground that is located in the

centre of the school premises is rented out on ca.

20 days per year for special programmes such as

wedding ceremonies, which are attended by up to

1000 people each.

The construction comprises a sanitation block with

urinals for men and women, pour flush toilets and hand

washing facilities. The urine is collected in two storage

tanks and reused as fertiliser. The brownwater from the

toilets is treated in a biogas settler tank (see Fig. 5). The

biogas will be used for cooking. The pre-treated water

is then added via a syphon tank into a vertical

flow constructed wetland and then used for irrigation.

The greywater will be used on site for the beautifica-

tion of the buildings with greywater gardens [5].

4.4. GTZ headquarters main office building

The main building of the GTZ headquarters is

located in Eschborn, near Frankfurt am Main,

Germany. When it became clear that the GTZ main

office building was to be renovated, the GTZ ecosan

team initiated and promoted the implementation of

an ecosan demonstration and research project as part

of the renovation. The renovation work began in

2004 and was finished in 2006. A modern system for

the separate collection of urine is now being used by

GTZ staff and a treatment and reuse system for brown

water is in preparation.

The main objectives of the project are to:

• Reduce the emission of pathogens, organics, nutri-

ents, and micro pollutants, such as pharmaceutical

residues and hormones to the public sewer system

and receiving waters

• Protect water resources

• Recover nutrients for agricultural use

• Demonstrate the implementation of the ecosan con-

cept in an urban context

• Contribute to the international dissemination of eco-

san by means of public presentations

• Research the technical, operational, legal, social,

economic and agricultural aspects

• Develop ecosan technologies and operation for mod-

ern urban buildings

Within the renovation works, 56 urine separation

toilets (model: Roediger NoMix) and 25 waterless

urinals (model: Keramag Centaurus) were installed.

Fig. 5. Biogas settler for brownwater treatment under

construction (source: seecon).


In addition, separate urine and brownwater pipes and

four urine tanks (see Fig. 6) with a total capacity of

10 m3 were built and the system started operation in

July 2006. Some difficulties during planning and

implementation of the innovative concept had to be

overcome. For example, the tank overflow had to be

shifted as the supplier did not deliver pressure-proven

tanks and the odour trap of the waterless urinals had

to be changed [2].

After several tests, the system is fully functioning

since mid 2007 and urine is being collected, stored and

transported to the University of Aachen where a solid

mineral fertiliser is extracted from the urine. As Ger-

man fertiliser law does not yet recognise urine as a fer-

tiliser the use of urine for laboratory or field research is

currently the only option of reusing urine in Germany.

5. Conclusion: challenges and outlook

In recent years, many successful ecosan pro-

grammes have been implemented in different countries

in rural and sparsely settled urban areas. A great deal of

experience has been made in these areas and a variety

of solutions exists that can be recommended for wide-

spread large-scale use in accordance with local physi-

cal, cultural and socio-economic conditions. Although

initial experiences with ecosan systems are available

from densely populated urban areas and new projects

for large-scale implementation are launched, further

research and development is urgently required to gain

the necessary experience in these more complex areas.

This knowledge would allow ecosan systems to be

implemented on a large scale, to show case the techni-

cal feasibility and the benefits of this new approach. In

addition to this, there are several other challenges

which need to be faced before ecological sanitation

systems will be widely adopted:

• Awareness of the alternatives offered by ecosan has

to be increased

• Reuse needs to be integrated into sanitation planning

processes from the very beginning

• Legal frameworks and technical standards need to be

revised

• We need a full cost analysis and comparison of the

environmental and health risks of all types of

sanitation

• Innovation-friendly investors are required, as well as

new financing instruments supporting private house-

holds investment

However, due to the huge potential shown, these

challenges must be overcome. Ecological sanitation

should be recognised as the new, promising, holistic

and sustainable approach to provide safe and decent

sanitation, reduce poverty, contribute to food security,

preserve our environment and maintain the natural

basis of life, in industrialised, developing and emerging

countries.

References

[1] Sustainable Sanitation Alliance (SuSanA), Effluent

Reuse from Constructed Wetland System, Haran Al-A-

wamied, Syria, 2009; Available from: http://www. susa-

na.org/images/documents/06-case-studies/en-susana-cs-

syria-constructed-wetland-2009.pdf.

[2] Sustainable Sanitation Alliance (SuSanA), Urine and

Brownwater Separation at GTZ Main Office Building,

Eschborn, Germany, 2009; Available from: http://

www.susana.org/images/documents/06-case-studies/en-

susana-cs-germany-eschborn-hausl-2009.pdf.

[3] Deutsche Gesellschaft fur Technische Zusammenarbeit

(GTZ) GmbH, 022 – Urine-Diversion Dehydration Toi-

let Centres at Navsarjan Boarding Schools, Gujarat,

India, 2006; Available from: http://www.gtz.de/de/doku-

mente/en-ecosan-pds-022-india-navsarjan-schools-

2007.pdf.

Fig. 6. Urine tanks installed in the basement of the gtz

main building, (source: GTZ).


[4] H.P. Mang, C. Werner and S. Kimmich, Overview of

worldwide ecosan concepts and strategies, in: C. Werner

et al., eds., Ecosan – Closing the Loop, Proceedings of

the 2nd International Symposium on Ecological Sanita-

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792; Available from: http://www.gtz.de/de/dokumente/

en-ecosan-symposium-luebeck-session-h-2004.pdf.

[5] M. Wafler and J. Heeb, Report on Case Studies of Ecosan

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http://www2.gtz.de/Dokumente/oe44/ecosan/nl/en-eco-

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[6] C. Werner, Reasons for and principles of ecological sani-

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on Ecological Sanitation, 7th–11th April, 2004, Lubeck,

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