Preface

This publication, which is divided into two parts, presents water treatment alternatives particularly applicable to rural water supplies in developing and newly industrialised countries, and describes processes for solid matter separation.

Part 1

contains a general introduction to the subject of rural water treatment. It describes the water treatment concept and raw water quality of different types of surface water, summarises the various water treatment processes used for solid matter separation, gives a brief account of bacteriological water quality improvement, provides a general layout of water supply schemes, and presents the development of roughing filter application

Part 2

elucidates design, construction and operation characteristics of different prefilters and roughing filters. It provides comprehensive information on filter layout, presents practical experience with different filters, describes selection criteria and procedure for adequate treatment plant design, discusses construction, operational and economic aspects, illustrates some design examples, and discloses valuable information on the practical implementation of the prefiltration technology.

Part 1 thus focuses on general aspects of rural water treatment and allows the interested reader to get a glimpse of the different challenges posed by the water treatment technologies. In Part 2, the reader will get a comprehensive view of the pretreatment processes applied to solid matter separation and a detailed description of the application of this technology.

This publication may be used as general textbook by teachers interested in rural water treatment technologies, by engineers who have to select and design appropriate treatment installations, and by operation and maintenance technicians who have to train treatment plant operators.

A technical publication is rather rational and dry. However, efforts have been made to formulate and illustrate this manual in a lively, easily understandable and attractive manner. Unexpected problems and challenges are often encountered with filter design, construction and operation. The "hardware information" is complemented with "software stories" on the complexity of rural water treatment implementation, which have been scattered as inserts throughout the text. I hope you will not only enjoy this book but relax and also find my adventures as rural water treatment promoter interesting.

The practical experience contained in the book is especially the result of the efforts made by our cooperation partners in numerous developing countries. During the last decade, I had the opportunity to develop with them efficient solid matter separation processes, to apply them in full-scale treatment plants, to find adequate solutions in difficult situations - but mainly, to learn from them. My special thanks therefore go to the numerous caretakers, training staff, design engineers and project officers who shared their experience with me. I also wish to thank the reviewers listed in Annex 10 for their helpful comments and suggestions. I take this opportunity to express my gratitude to the various institutions and to the Swiss Development Cooperation which strongly supported the development and implementation of the roughing filter technology.

Duebendorf, October 1996

Martin Wegelin