. Preventive medicine and hygiene. in a recognizeddeterioration of property values. The processes nsed for the treatmentof sewage not infrequently result in odors that may be objectionable overconsiderable areas. Where the treatment works are entirely covered, as 974 SEWAGE DISPOSAL some kinds of works may be, little or no nuisance may result, butwhere, for example, the sewage is first submitted to putrefaction in aseptic tank and the septic effluent then sprayed into open air upon thesurface of sprinkling filters, this exposure of the atomized liquid resultsin the liberation of odors that may
. Preventive medicine and hygiene. in a recognizeddeterioration of property values. The processes nsed for the treatmentof sewage not infrequently result in odors that may be objectionable overconsiderable areas. Where the treatment works are entirely covered, as 974 SEWAGE DISPOSAL some kinds of works may be, little or no nuisance may result, butwhere, for example, the sewage is first submitted to putrefaction in aseptic tank and the septic effluent then sprayed into open air upon thesurface of sprinkling filters, this exposure of the atomized liquid resultsin the liberation of odors that may reach distances up to perhaps half amile from the plant, depending upon the amount and character ofsewage treated, the local topography, prevailing direction of the wind,humidity in the atmosphere, and other conditions. Frequently high winds will carry the spray itself for several hundredfeet with inevitable bacterial pollution of the air. In the operation ofsprinkling filters also it has been found that at certain seasons of the. Fig. 130.—Septic Tank and Chemical Precipitation Tanks at Rochdale, England. year swarms of flies breed in the porous beds. These are very trouble-some, if not dangerous, in the immediate vicinity of such works. Inconsidering the need of sewage treatment it is proper to balance thesepossible nuisances against those resulting from the discharge of un-purified sewage into a body of water. It not infrequently happens thatthe installation of sewage treatment works merely substitutes onenuisance for another. Nuisances Caused by Trade Wastes.—It not infrequently happensthat the greatest nuisance in streams is due not so much to domesticsewage as to the presence of trade wastes that may be discharged intothe stream directly, or that may be allowed to flow into the streamthrough the sewers. Eor example, the discharge of spent dye liquorsmay color the water of a stream for many miles; petroleum wastesfrom gas works may cause iridescent films to form upon
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
