Slow sand filtration

This review will initially consider the history and early development of the slow sand filtration process and will progress to examine the present design in some detail and will also touch upon construction methods. Theoretical aspects will be examined. Operation and management will be dealt with, with cleaning and resanding techniques being particularly considered. The advantages of slow filtration will be explored, especially the simplicity of operation and the ability of the process to remove potentially pathogenic organisms from water. Of the disadvantages, it will be the difficulties associated with the filtration of appreciably turbid waters that will be given most space although the effects of algal blooms will also be investigated. Emphasis will be given to techniques available for the pretreatment of turbid source waters and also, particularly, to the applicability of slow sand filtration to the developing world.