Produced by Chris Curnow, Carol Brown, and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) NATURAL & ARTIFICIAL SEWAGE TREATMENT BY LIEUT.-COL. ALFRED S. JONES, V.C. ASSOC. M. INST. C.E., FELLOW AND MEMBER OF COUNCIL OF THE SANITARY INSTITUTE, ETC. AND H. ALFRED ROECHLING M. INST. C.E., F.G.S., FELLOW OF THE SANITARY INSTITUTE, ETC. [Illustration: Printer's Logo] London E. & F. N. SPON, LTD., 125 STRAND New York SPON & CHAMBERLAIN, 123 LIBERTY STREET 1902 PREFACE. The Authors, some time ago, read before different Societies of professional men, Papers[1] dealing with the Natural and Artificial Purification of Sewage, and as these were favourably received, the thought occurred to them that the time might be opportune for making the information there given available for a wider public. As, however, a mere republication of the Papers would have been against the rules of the Societies concerned, the Authors decided to re-write entirely the subject matter, and to bring it up to date, so that the present publication is not a mere repetition of their old Papers clothed in a new garb, but an entirely fresh publication, right up to date. The Authors hope that they have given the information in such a form as to be readily available for District Councillors, Sanitarians, and all interested in this complicated subject. When considering natural and artificial sewage treatment, it ought to be borne in mind that in the natural treatment we have to deal with one treatment only, and that, in order to bring the results obtained from artificial processes up to the same standard, the artificial treatment ought to be supplemented by a treatment for the removal of nitrates from the effluent, and another for the removal of pathogenic micro-organisms, which means one treatment in natural, as against three separate treatments in artificial purification. In addition to this it must be understood that, owing to the great losses by evaporation and by growing plants, which are continually at work on sewage farms, especially during the summer months, when, as a rule, the flow of water in the brook that takes the effluent is smallest, the quantity of the effluent from the natural treatment is probably only from one-half to one-third that resulting from the artificial treatment, which is a point of very great importance.