in uk buildings by tom bishop. what grey water is why recycle it how its treated applications ...
TRANSCRIPT
Grey WaterIn UK Buildings
By Tom Bishop
What grey water is Why recycle it How its treated Applications Potential savings Future prospects
Contents
Typical Domestic Water Cycle
Black water plumbing
White water in
Domestic use
Grey water plumbing
Sewage network
Water treatment facility
Grey and Black Water
32%
5%
33%
7%
23%
Typical Household water usage (%)
Toilet
Hand basins
Bath / Showers
Kitchen
laundry
Grey water:
Typically no pathogensReduced bacteriaHigh biological oxygen demand
Black water:
PathogensBacteriaHigh biological oxygen demand
Growing Water demand:◦ Changing climate◦ Increasingly water
intensive lifestyle◦ Urbanization◦ Population growth◦ Increasing usage in
industry and agriculture
Why bother to Recycle Grey Water?
Areas of relative water stress
Is rain water free?◦ Costs in..
Collection Treatment Transportation Leakages
Why bother to Recycle Grey Water?
52%
23%
17%
8%
Public water supply, England and Wales. 2007
Household use
non-household use
network leakage
Customer & other leakages
More efficient water usage◦ Only 7% of household water is used for drinking
and cooking◦ Large levels of potable water used for activities
which do not require high quality water e.g.: washing cars flushing toilets Irrigating gardens
Why bother to Recycle Grey Water?
?
Primary treatment – Settlement tank◦ screens out scum (oils & greases) and sludge
(course solid particles)
Treatment
Costs◦ £200 to £1000
for tank depending on size
Secondary treatment – Sand filter
Treatment
Grey water from settlement tank
Fine sand
Gravel
Filtered water out
Total system costs
◦ £500 to £2000 for basic filter systems
◦ £2000 to £10000+ for fully integrated building system; including pumps pipes tanks etc.
Secondary treatment - Wetlands
Treatment
From settlement tank To irrigation
Costs◦ Approximately £100/m2 (surface area)◦ 2-3m2 required for 100 litres per day
throughput
Toilet flushing◦ Sloan AQUS Grey water
System- Small scale stand alone, £400 Filter with chlorine tablets 30% reduction ?? Customers claim
approximately 8 year payback time
Applications
Toilet flushing◦ Aquawiser residential Grey
water System- fully integrated £2000-£3000 for typical 5
person house Actually achieves 30%
reduction
Applications
Grey water from
bath/shower to treatment
Treatment tank & pump
Mains top up Overflow
To cisternsTreated grey
water
Irrigation◦ Primary treated grey water - Subsurface irrigation
◦ Secondary treated grey water – surface micro drip irrigation.
Applications
5 person household using Aquawiser system ◦ Money
150 litres per person day = 274000 litres pa 30% saving = 82200 litres pa £1.9 per m3 water = £ 156 saved per year £2000 system will payback in under 13 years
◦ CO2
0.59kg CO2 / m3 of treated water 0.59(kg/m3)* 82.2(m3)* 1.5(leakages)
= 63kg of CO2 saved per house hold pa Minor saving but if multiplied across the country huge
potential savings.
Potential savings
Government targets to reduce mains water usage from 150 to 130 litres per person per day by 2030
Government water efficiency standards for all new homes
Increasing water stress and rising prices will increase feasibility of re use systems
As more people adopt grey water systems government guild lines/ regulations will be needed
Future of grey water reuse
UK needs to value water more highly and not inadvertently waste it.
Grey water reuse is an effective method to increase the efficiency of water usage
Although not particularly feasible for the average house it is set to become more popular in the near future.
Conclusion
WHO http://www.emro.who.int/ceha/pdf/Greywter%20English%202006.pdf
DEFRA http://www.defra.gov.uk/environment/quality/water/strategy/pdf/future-water.pdf
AquaCo http://www.aquaco.co.uk/3rd_display.asp?Page_ID=12
Sloan AQUS http://www.greenlaunches.com/recycle/sloan-aqus-greywater-system-to-help-recycle-bathroom-water.php
Bull, J. (2010, 07). The carbon footprint of tap water. Retrieved 02 09, 2011, from oCoCarbon: http://oco-carbon.com/2010/07/18/the-carbon-footprint-of-tap-water/
References
Any Questions?