. The sanitation of cities. NEW YORK CITY, N. showing proposed number and location of district or divi-sional sewage treatment plants (indicated by black symbols)suggested by the Metropolitan Sewerage Commission 8i ilinimiii. 82 CHAPTER VIII DIFFICULT PROBLEMS FOUND INTREATING SEWAGE One of the greatest difficulties connected withsewage treatment is the disposal of sludge fromseptic tanks and settling tanks, as the sludge fromthese tanks is highly putrescible. This has led tothe invention of two forms of tanks, each of whichattempts to carry the septic treatment of thesludge to such a
. The sanitation of cities. NEW YORK CITY, N. showing proposed number and location of district or divi-sional sewage treatment plants (indicated by black symbols)suggested by the Metropolitan Sewerage Commission 8i ilinimiii. 82 CHAPTER VIII DIFFICULT PROBLEMS FOUND INTREATING SEWAGE One of the greatest difficulties connected withsewage treatment is the disposal of sludge fromseptic tanks and settling tanks, as the sludge fromthese tanks is highly putrescible. This has led tothe invention of two forms of tanks, each of whichattempts to carry the septic treatment of thesludge to such a point that when discharged it willnot cause a nuisance. These tanks depend upon the assumption thatwhen the so-called septic action has been carriedto its extreme, the unstable organic matters whichare attacked by anaerobic bacteria, become in-capable of further putrescence and dissolve, orsplit up; part going into solution, part into inertmatters, and part remaining as organics, that donot readily putrefy, which are deposited with themineral materials present on the bottom of thetank. The greatest problem met by designers of tankshas been to design a tank in which the reten- 83
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Keywords: ., bookcentury1900, bookdecade1920, bookidcu3192400497, bookyear1921
