Davyhulme Sewage Works
Davyhulme, Trafford, Manchester, UK
Thomas de Courcy Meade
Gilbert John Fowler
date 1889 - 1894, 1957 - 1967
era Victorian |
category Sewage/Sewer |
The use of activated sludge treatment was pioneered at Davyhulme Sewage Works. It is now one of the largest wastewater treatment plants in Europe. A scheme is underway to use biomethane from the plant as a fuel source for cooking and heating.
By the mid 19th century, Manchester’s inadequate sewage infrastructure for its growing population was a serious cause for concern. Before 1889, the city was served by a network of local sewers that tended to discharge untreated effluent into rivers and streams. The first integrated system of 21 brick interceptor sewers was built 1889-9. They converged on Davyhulme. Some 56km of these original sewers are still in use.
Davyhulme Sewage Works was set up on 38 hectares, 8km from the city centre. This was later enlarged to 67 hectares. In addition to the 11 treatment tanks — total capacity 55 million litres — there were eight filter presses, pumping engines and sludge wells. The work's engineer was Manchester's municipal engineer, Thomas de Courcy Meade.
Raw sewage arriving at the plant was screened and chemically treated with lime and iron sulphate. The effluent then passed through precipitation tanks and the resulting sludge was filtered. The liquid from the precipitation tanks was spread over an area of 15 hectares, presumably to evaporate.
The works were converted to bacterial treatment in 1904-7 and had primary and secondary contact beds. During the early 1910s, Gilbert Fowler pioneered the use of activated sludge treatment for up to half of the flows received at the works. The activated sludge plant was completed in 1934.
A second system of 16 trunk relief sewers for Manchester was built between 1911 and 1973. These also converge on Davyhulme. By 1954, the bacteria contact beds weren't treating the sewage effectively and were replaced by a new plant. The activated sludge plant deteriorated over the next decade and it too was replaced by new works.
The 1957-67 works cost £6.2m and consisted of modifications to the six-channel inlet and screens, storm sewage tanks, primary sedimentation, aeration, sludge treatment and power generation. The existing 16 settlement and storm sewage tanks were demolished and replaced by six new storm sewage tanks with a total capacity of 91 million litres. The reinforced concrete tanks are founded on 400mm diameter concrete piles and the tank walls are 530mm thick.
There are now eight aeration units, each 10.7m wide and 117.3m long with 3m depth of water and containing 11 aeration cones. Aerated sludge is passed into 12 final tanks where the solids settle out and the effluent passes over weirs into another aeration channel before discharge to the Manchester Ship Canal.
Sludge from the settlement tanks passes through three phases — digestion, consolidation and disposal. At Davyhulme, there are four 26.5m diameter digestion tanks with a total capacity of 39 million litres. The tanks are founded on sandstone 9.1m below ground level and have post-stressed concrete walls 250-380mm thick.
Sludge is agitated by three screw pumps per tank and then flows under gravity into the six 30.5m diameter consolidation tanks, total capacity 21 million litres. It is thickened and the liquor fed into settlement tanks before being returned to the inlet works. It is then pumped to storage tanks for onward disposal at sea. If disposal at sea is not possible, it is pumped 4.8km south west to a lagoon at Flixton. Power for the whole plant is generated by six oil-fired engines coupled to 1,225kW 6,600V alternators.
Anaerobic digestion of sewage produces biogas, 50-70% of which is methane similar to natural gas. By 2012, it is intended that this biomethane will be collected and used to supply the cooking and heating demands of up to 5,000 households via existing gas mains. A £4.3m pilot scheme to power 500 homes is underway.
The CHP (combined heat and power) plant at Davyhulme runs on biogas and generates around 3MW of electricity. Heat is used to operate the anaerobic digestion reaction.
Primary sludge digestion plant (1957-67): John Laing Construction Ltd
Secondary sludge treatment plant (1957-67): A. Monk & Co Ltd
Sedimentation plant, storm water tanks (1957-67): Hussey, Egan & Pickmere Ltd
Inlet works, power station (1957-67): G. Percy Trentham Ltd
Outfall, jetty (1957-67): Lehane, Mackenzie & Shand Ltd
Aeration plant, final tanks (1957-67): George Wimpey & Co Ltd
Piling (1957-67): Holmpress Piles
"Manchester’s Main Drainage System Past and Present"
by Geoffrey F. Read, City Engineer and Surveyor
Report to the City of Manchester Highways Committee, 24th July 1979
"The extensions to the Davyhulme Sewage Works (1957-67)"
by G.L. Symes
ICE Proceedings, Vol.38, Issue 4, December 1967, pp.577-594