Water for a Green City

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WATERSAVE, IMPERIAL COLLEGE- 26th June
2001 Water reuse - Some case studies Chris
Shirley - Smith Director, Metropolitan Water
Company
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50
Pennon Plc
Enviro-Logic Ltd
100
South West Water Ltd
Enviro-Logic
MetropolitanWater
Albion Water
(Rising groundwater)
(Regulated business)
(Non regulated business)
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Potential Uses of Londons Rising Groundwater
Schools
Industrial use
Office use
Industrial
20 potable
37 potable
Estates
80 non-potable
Hospitals
Housing
63 non-potable
Estates
Park and
Gardens
Household use
52 potable
48 non-potable
LONDON
CLAY
LONDON
CLAY
CHALK
CHALK
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GREEN CLUSTER SUPPLY
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Potable and Non-potable Uses Potable Potable
water is water provided for the purpose of
drinking and must meet all the Drinking water
Quality Regulations. Private Supplies are
regulated by Local Authority Environmental Health
Departments. They have a requirement to sample
the water at a specified frequency.
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Non-potable Water Non-potable water is non
regulated and can be treated (or not) to meet
specific end-use. There is a Duty of Care by
agreement between the supplier and the provider
of a service (e.g. the Local Authority) to ensure
that the agreed standard is complied with.
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Uses for Non-potable Water might
include - Swimming baths - Laundries - Toilet
Flushing - Parks Landscape Irrigation - Sewer
Jetting and Public Area Cleansing - Heating/
Cooling cycles for Buildings
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GREY AND GREEN RECYCLED WATER The need for a new
definition GREY Water - Water collected from
baths, basins, showers etc. Cleansed, and
returned as GREEN Water.
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DEFINITION OF GREEN WATER Green water - is
effluent which has been treated to a grade
suitable for provision as a non-potable supply,
usually, but not exclusively in parallel with a
potable supply for industrial, residential or
public use. May or may not include blend of
rainwater. - lacks turbidity, is pathogen free,
and meets criteria for tertiary treatment
(typically lt 10mg/l BOD and Suspended Solids) -
should be clearly identified as a separate
supply, by the use of a green tinged dye at a
specified dilution and plumbed in green pipework
which is not readily connectable to potable
supply
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GREEN ROOFS MWC is also actively engaged in
water conservation. MWC has patented a design
for the recycling of water (Grey Green) through
a reed bed-type biological cleansing system
located on the roof of, for example, a
multiple-occupancy, multi-storey urban dwelling
such as a block of flats. This design is
currently being developed and tested for
efficiency, optimum water retention period,
pitch, weight and other factors important both to
building design and water supply purposes. Our
research partner is Middlesex University. It
should be available for specification by
architects by late 2001.
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The Economics of Green Water (1) Average Water
Consumption per person 150l/ day This is
equivalent to about 55m3 (or tonnes) / year The
volume will vary with age and lifestyle of
individual A 6 person household therefore uses
about 350m3/ year
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The Economics of Green Water (2) Cost of water
(only) 2001/2 from Thames Water
59.5p/m Standing Charge on 15mm supply
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52.70, or a household of 6 people c 220
(water supply only) Cost of sewerage is linked to
consumption volumes. Objective of Green Roof
system (blending rain water and treated grey
water to make green water) to save 30 min. Hence
annual saving for 6 people c70 (This does not
include original cost of installation)
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A typical Green Roof environment
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BEDZED Beddington Zero Emissions Development, a
sustainable development in South
London Bio-Regional undertook the community
consultation with a series of meetings with local
people. The football pitch appears to have been
the determining factor! Local Residents say
Please build Bedzed!
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BedZED scheme - nb football pitch top left!
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Layout for water systems
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SUMMARY MWC is concerned with - Providing
customers with alternative, cheaper and
sustainable sources of Potable and Non-potable
water - The practical application of solutions
to the use of green water from several sources
for urban water recycling
Water for a Green City