. Preventive medicine and hygiene. pplication is usually between 300,000 and 800,000 gallonsper acre daily, one acre serving a population of about 5,000. Wlienproperly operated and receiving the sewage of septic tanks contact beds 970 SEWAGE DISPOSAL are capable of removing about 65 to 70 per cent, of the organic matter,80 to 85 per cent, of bacteria, and 85 to 90 per cent, of suspended mat-ter. Contact beds become clogged with use, and after periods varyingfrom five to eight years it is necessary to remove the stone or coke andclean them. Trickling Filters.—Trickling filters, otherwise called
. Preventive medicine and hygiene. pplication is usually between 300,000 and 800,000 gallonsper acre daily, one acre serving a population of about 5,000. Wlienproperly operated and receiving the sewage of septic tanks contact beds 970 SEWAGE DISPOSAL are capable of removing about 65 to 70 per cent, of the organic matter,80 to 85 per cent, of bacteria, and 85 to 90 per cent, of suspended mat-ter. Contact beds become clogged with use, and after periods varyingfrom five to eight years it is necessary to remove the stone or coke andclean them. Trickling Filters.—Trickling filters, otherwise called sprinklingfilters or percolating filters, consist of beds of porous material suchas broken stone, coke, or clinkers upon which the sewage is sprinkled andthrough which it percolates to underdrains laid on a tight floor entire bed is arranged with reference to complete aeration through-out, in order that the organic matter of the sewage may become thor-oughly oxidized. The suspended matter of the sewage is not perma-. FiG. 129.^—Tbickling Filter at Birmingham, England. nently retained in the beds, but is carried out in the effluent, which isturbid and requires subsequent clarification. The object of the tricklingfilter is to change the character of the organic matter so as to renderit non-putrescible. The sewage is applied to the beds by sprinklingthrough fixed sprinklers or by use of traveling sprinklers, rotary orrectangular, operated by the discharging sewage or by power. The rateof application varies from to million gallons per acre daily,one acre of trickling filter serving a population of 10,000 or beds vary in depth from 5 to 10 feet, coarser material being usedfor the deeper beds. Well-operated sprinkling filters receiving theeffluent from plain sedimentation or septic tanks are capable of remov-ing from 85 to 90 per cent, of the suspended matter and from 90 to 95per cent, of bacteria, yielding an effluent that is non-putrescible. Thisme
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Keywords: ., bookauthorwh, bookcentury1900, bookdecade1910, booksubjecthygiene
