P26. Protection of the marine environment and of watercourses by screening

1. A study has been carried out by the Water Research Centre and Welsh Water Authority over a period of three years to evaluate the efficiency of a range 01" screening devices (refs 1 and 2) . Some 21 screens were tested. The following tests have been applied:

(i) Immersion in the foul flow of a series of meshes (17 mm, 12 mm and 6 mm) in a frame before and after the screen to measure the solids loading.

Use of a hydrodynamic separator to capture screenings to estimate screen loadings and the efficiency of removal.

A 1 mm wedge wire run-down screen to give screenings loadings and removal (as above).