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The filtration of public water-supplies / Third edition, revised and enlarged. cover

The filtration of public water-supplies / Third edition, revised and enlarged.

Chapter 45: REMOVAL OF COLOR.
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About This Book

This book presents a practical, engineering-focused treatment of water filtration for municipal supplies, combining historical perspective, design principles, and operational guidance. It explains types of filters, construction of beds and underdrains, selection and grading of sands and gravels, rates of filtration, head loss, and mechanisms for regulating flow. Procedures for cleaning, sand-washing, and intermittent operation are described alongside theoretical and bacteriological considerations that bear on efficiency. Methods for measuring and removing turbidity and color, the effects of suspended mud, coagulation practices, and numerous design examples and appendices illustrate how to plan, build, and maintain effective filtration works.

REMOVAL OF COLOR.

Peaty coloring-matter is almost perfectly in solution, and only a portion of it is capable of being removed by any form of simple filtration. In order to remove the coloring-matter it is necessary to change it chemically, or to bring it into contact with some substance capable of absorbing it. For this reason sand filtration with ordinary sands, having no absorptive power for color, commonly removes only from one fourth to one third of the color of the raw water.