- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 29 Mar 2019
Greywater recycling at the Millennium Dome
Thames Water, struggling to balance increasing demand in the densely-populated south
- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 29 Mar 2019
Greywater recycling at the Millennium Dome
Thames Water, struggling to balance increasing demand in the densely-populated south-east, an area which receives less annual rainfall than some Mediterranean regions, approached the New Millennium Experience Company (NMEC) suggesting a collaborative effort to develop an innovative approach to water management on the site of the Millennium Dome in Greenwich. The main objectives of the project included demonstrating and researching water recycling technologies, evaluating water efficient appliances and investigating public attitudes to water recycling initiatives.
 The Parameters
The New Millennium Experience Company anticipated a maximum attendance of 35,000 people per day, and over ten million during the course of the exhibition year. This yielded a requirement for 500m3 per day for wc and urinal flushing. Three potential sources of secondary water for recycling were identified on site:
The surface area of the Dome itself is some 90,000m2. Rainwater run-off from the roof is collected via a gutter and channelled through specially designed hoppers, which feed into the surface water drainage system. A maximum of lOOm2/day can be collected in this way.
London has had a problem with rising groundwater since 1970 due to a decline in pumping rates, caused by the changing industrial and commercial base. A 11Orn borehole was drilled on the site and water pumped direct from the aquifers.
 Treatment Methodology
Since the rainwater run-off was collected swiftly and thus uncontaminated, open reedbeds were an appropriate choice. Rainwater was passed through the first reedbed, designed for stormwater treatment, followed by a second reedbed that functioned as a storage lagoon. The latter also performed a tertiary treatment function. The beds, approximately 0.6m deep, had a 0.5% gradient, and were filled with washed river gravel planted with the common reed. An arrangement of educational boards and a walkway running through this landscape allowed the general public to understand the operation of this 'natural' form of water treatment.
Thames Water Research carried out a range of pilot scale trials using biological aerated filters (BAF) followed by a variety of membranes with specific emphasis on soluble bio-chemical oxygen demand (BOD) removal using synthetic greywater. Another consideration was dealing with modern soaps that would be contained in the greywater discharge. The trials indicated that tight ultra-filtration membranes were the most appropriate for handbasin and shower greywater.
Water from the borehole was tested to establish the groundwater quality. A problem with hydrogen sulphide gas was experienced together with a much higher than anticipated salt and iron content. A system was devised to dose the groundwater with hydrogen peroxide to oxidise any metal contaminates, then pass the water through granular activated carbon to remove the organic contaminates. Membrane filtration followed carbon exchange where ultra-filtration removed residual organics and a reverse osmosis (RO) membrane desalinated the groundwater. 