| Surface water treatment by roughing filters - A design, Construction and Operation manual (1996) |
by Martin Wegelin
Duebendorf, October 1996
This publication presents the concept, design and field experience of roughing filters applied as pretreatment prior to slow sand filters. It describes treatment and purification processes which convert turbid surface water into safe drinking water. The presented treatment methods are simple, efficient and reliable and, therefore, appropriate for rural water supply schemes.
Surface water treatment generally requires at least two treatment steps. The first step, also called pretreatment, concentrates mainly on the removal of solids. Prefiltration by roughing filters is a simple and efficient process for solid matter separation. However, roughing filters also contribute to a bacteriological water quality improvement. The second step, commonly considered as main treatment, is applied especially to remove or destroy the remaining microorganism by slow sand filtration and chlorination.
This manual mainly focuses on the design, construction and operation or prefilters and roughing filters. It is recommended as textbook for teachers and students, as design manual for engineers and as operation and maintenance guidelines for technicians. The manual draws its valuable information from a vast field experience documented by the small stories scattered throughout the text.