SAND FILTRATION OF ALGA LADEN WATERS

Abstract

For water supply schemes it is becoming increasingly necessary to rely upon surface waters of streams, rivers,lakes and impoundments in which numerous kinds of microscopic organi grow prolifically and constitute part of the natural flora and fauna of the water habitats. These microorganisms invariably 'r enter the purification plant and give rise to various difficul-ties in sedimentation tanks, filter beds, cause undesirable tas and odour and render the water unpalatable. Algae entering fi1- tens cause excessive clogging building up too much head loss considerably shortening the filter rins with consequent economic losses. It has been observed that this is posing a real problem to Indian water supplies especially during summer when the growth of algae is prolific. In view of the implications of the problem, a study of• the behaviour of rapid sand filters with alga laden waters is worthwhile and interesting. Attempt has been made to study the removal characteristics in the case of uncoagulated waters and waters coagulated with alum, using a laboratory filter model. The effect of applying algicides such as Hopper sulphate or chlorine on filtration has also been studidd with a few runs.