the water treatment works.
The Discreen was chosen by the customer because of its innovative operating principle. Constructed using a series of shafts that are fitted with overlapping and intermeshing discs, the rotation of the discs gently convey solids and debris across the face of the screen, whilst allowing the main water flow to pass through the disc stacks. The debris is then ejected back into the river flow by individual comb bars incorporated in the Discreen design. This has removed the need to collect and manually dispose of extracted debris, significantly reducing the labour costs associated with solids disposal and equipment cleaning.
Mono commissioned a team of divers to remove the old drum screens and excessive debris that had built up around
the intakes to assist installation of the new equipment. The Discreen frames were assembled underwater and Mono used a 70 tonne extending crane to manoeuvre the Discreens into place for installation.
The lagoon intake, fitted with four 14 shaft L Series Discreens across an 8.8 metre wide section, is the preferred intake for the treatment works. Any fine unscreened debris settles in the lagoon before the abstracted water reaches the pumps feeding the filtering house. As the lagoon intake is alongside a popular public right of way, safety measures were put in place to offer protection to the public.
The Upper intake was fitted with two 10 shaft L Series Discreens, across two inlet chambers over a 7.2 metre wide section. The screens did not require complex foundations and there is practically no structure on view above the bank level, enabling them to blend in well with the environment.
A spokesperson for Bournemouth and West Hampshire Water says: “We looked at a number of products for Knapp Mill WTW, and Mono was able to provide the most cost-effective and reliable solution. The previous drum screens required constant wet-washing, adding to their lifelong operating costs, whereas the Discreens are self cleaning with low operating costs.”