THE SPECIFICATION OF FILTERING MATERIALS FOR RAPID-GRAVITY FILTRATION

A UK standard for the specification, approval and testing of filtering materials has recently been published by British Water (formed by the merger of the British Effluent and Water Association and the British Water Industries Group) in response to an identified need. This paper reviews the considerations during the preparation of the standard and provides a technical background. The approach has been to base the sta ndard on parameters which affect the behaviour of the material during filtration, rather than to specify material composition and appearance , which are unimportant. Standards and specifications are a basis for testing, and the inclusion of irrelevant parameters can lead to unnece ssary work.