. The sanitation of cities. enings, into the lower chamberwhich was placed between the two upper cham-bers, through which the settlings and sludge passby gravity. The lower, or digesting, chamber hasits bottom, which is the deepest part of the tank,formed in one or more hoppers, or inverted pyra-mids, provided with sludge outlet pipes. Theupper part of this chamber is at the same eleva-tion as the upper part of the flowing-throughchambers, and a portion of the sewage is per-mitted to pass through it. The flowing-throughchambers have a network of slats formed intotrellises which are placed acro
. The sanitation of cities. enings, into the lower chamberwhich was placed between the two upper cham-bers, through which the settlings and sludge passby gravity. The lower, or digesting, chamber hasits bottom, which is the deepest part of the tank,formed in one or more hoppers, or inverted pyra-mids, provided with sludge outlet pipes. Theupper part of this chamber is at the same eleva-tion as the upper part of the flowing-throughchambers, and a portion of the sewage is per-mitted to pass through it. The flowing-throughchambers have a network of slats formed intotrellises which are placed across the direction ofthe flow, the purpose of which is to act as aremover of colloids by adsorption, it beingclaimed that fine particles of organic matter ina colloidal state tend to adhere to surfaces wherethey are readily attacked and liquefied by bac-teria. 85 ^be Sanitation of Cities But few plants with tanks of this type have beenbuilt. The effluent was little if any better thanfrom a septic tank. The sludge was not suf-. ESSEN, GET^MANYImhofF tank sewage treatment plant ficiently digested to dry on a bed without causingodors. At Norwich, England, using this systemit was necessary to dispose of the sludge intrenches. The Imhoff tank is a more successful effortto solve this very difficult problem. Inventedat Essen in Germany, it is a further development avis principle. It discards the col-nd provides two chambers, an upperor flowing-through chamber for the sewage, in-tended for plain sedimentation, and a lower ordigestion chamber, for the settling matter orsludge. The upper chamber is designed withsharply sloping bottom surfaces, provided with 86 Difficult lproblern0 founb in ZTreatiiuj Sewaoe slots at the lowest point, through which the set-tlings enter the lower, or digesting chamber; abaffle or fender is arranged under the slots to pre-
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Keywords: ., bookcentury1900, bookdecade1920, bookidcu3192400497, bookyear1921
