Davyhulme Sewage Works
Davyhulme Sewage Works is the main waste water treatment works for the city of Manchester, and is one of the largest in Europe. It was opened in 1894, and has pioneered the improvement of a number of treatment processes.
With the growth of population in the late nineteenth century, and the proliferation of water closets, the rivers around Manchester were becoming grossly polluted, and the City of Manchester decided to build two deep level sewers to intercept existing sewers. When the first one reached Davyhulme, further extension was blocked by the construction of the Manchester Ship Canal, and so a treatment works was built there.
Treated sludge was loaded into ships and discharged into the Mersey estuary from 1898. Over the next 100 years, seven ships were used to transport the sludge. At first, ships used the ship canal to transport sludge from the works, but later a pipeline was built to Liverpool, and the ships made a much shorter journey.
An early feature was a laboratory, where trials of various types of filter were carried out, and incoming effluent was analysed. Attempts to improve the treatment process proved successful and in 1914 Edward Arden and William T. Lockett, demonstrated the Activated Sludge Process, which was soon in use worldwide. A second deep level sewer, started in 1911, eventually reached the works in 1928, and to cope with the increased flows, half of the sewage was fed into a new Activated Sludge plant. Three separate operating systems were installed, so that comparisons on their efficiency could be made. A second Activated Sludge plant was built between 1955 and 1966, and the control system on the first was upgraded between 1970 and 1973.
The above information is largely condensed from the excellent Wikipedia entry.
See 'Manchester Main Drainage Works' article in Engineering 1894/10/19, which notes that in passing under the Bridgewater Canal, the main outfall sewer had to be constructed in two cast-iron cylinders, each 8 ft. 9 in. in diameter, owing to lack of headroom and the stipulation that a depth of 9 ft. in place of 5 1/2 ft. was to be provided. The work was done half at a time by means of cofferdams made of sand ; and the canal had to be temporarily widened in order to provide for uninterrupted traffic.
See here for numerous photographs of the sewage works [1]