. The principles of hygiene; a practical manual for students, physicians, and health-officers . , as the absorptive power of thesoil is feeble at low temperatures. From a sanitarystandpoint the system has had a most careful investiga-tion, especially in England, and these observations havefailed to show the origin of any case of contagious dis-ease from it. Since 1870, when the Rivers Pollution Commission of 158 THE REMOVAL AND DISPOSAL OF SEWAGE. England proposed in their report the purification ofsewage by irrigation of cultivated land, the system hasbeen introduced into over 145 English tow
. The principles of hygiene; a practical manual for students, physicians, and health-officers . , as the absorptive power of thesoil is feeble at low temperatures. From a sanitarystandpoint the system has had a most careful investiga-tion, especially in England, and these observations havefailed to show the origin of any case of contagious dis-ease from it. Since 1870, when the Rivers Pollution Commission of 158 THE REMOVAL AND DISPOSAL OF SEWAGE. England proposed in their report the purification ofsewage by irrigation of cultivated land, the system hasbeen introduced into over 145 English towns. OtherEuropean towns have also adopted it, including Berlin,Breslau, and Dantzig. In America it has been introducedat Wayne, Pa., Pullman, 111., Greenfield, Mass., andBerlin, Out. In the western States, where there is ascarcity of water, sewage has been utilized for irrigationwith considerable success. In California, Fresno, Pasa-dena, Redding, Los Angeles, Santa Rosa, and Stockton,all irrigate with sewage. In Colorado, Colorado Springsand Trinidad utilize sewage for irrigation Fig. 42.—Fields flushing tank. Helena, Mont., and Cheyenne, Wyo., also utilize sewagein this manner. In order to operate satisfactorily the system requires 1acre of area for each 2000 persons (2 square meters perperson), and consequently it is not adapted for localitieswhere cheap land in sufficient quantities and of suitablequality cannot be obtained. Large towns must, there-fore, usually avail themselves of some other method ofsewage purification. Purification by Means of Sand Filters.—The filtrationof sewage by means of specially constructed sand filters,or by means of a natural sandy, loamy soil, is efficacious MODERN ME THODS OF SE WA GE PURIFICA TION. 159 in the purification of sewage. Because of the absence offree oxygen in sewage the filtration must be carried onby the intermittent method in order to give the nitrify-ing bacteria an opportunity to recuperate. These filtersare us
Size: 1779px × 1405px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjecthygiene, bookyear1901
