Disposal and purification of factory wastes or manufacturing sewage / by H. W. Clark.

Date:
1910
Catalogue details

Licence: In copyright

Credit: Disposal and purification of factory wastes or manufacturing sewage / by H. W. Clark. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    Wastes from Tanneries.1 Tannery A. During the past fourteen years the wastes from three tanneries have been experimented upon. The first tannery investigated was engaged in preparing and tanning sheep skins. The daily volume of the waste varied from 20,000 to 50,000 gallons, and was composed of a thick, offensive liquor varying in color as different aniline dyes were used. The amount of organic matter present was large and in an advanced state of putrefaction. It seldom contained any substance of a character to check bacterial action and was, therefore, easily nitrified. The sludge was at times great in volume and rich in fats and nitrogenous matters. A filter was constructed at this tannery, containing 2 feet in depth of sand of an effective size of 0.14 millimeter, over gravel underdrains; and sewage, made up of a mixture of the waste liquors from all the proc- esses carried on at the tannery, was first applied to it on Sept. 27, 1895, at an average rate of 55,000 gallons per acre daily. During a large part of its period of operation, however, the rate was 25,000 gallons per acre daily, but even at this rate the filter became clogged quickly by matter in suspension in the waste. The following analyses show the character of the liquor as applied to and of the effluent from this filter during its period of operation: — Average Analysis of Liquor applied to Filter. [Parts per 100,000.] Ammonia. Kjeldahl Nitrogen. Chlorine. Nitrogen as — Oxygen Consumed. Free. Albuminoid. Total. In Solution. Nitrates. Nitrites. 3.74 3.16 1.91 5.92 387.20 .16 .0015 61.25 Average Analysis of Effluent from Filter. 2.65 0.48 0.20 0.69 284.25 .60 .0068 7.92 It was evident that better nitrification and higher rates of filtration could be obtained if suspended matter was removed from the sewage before filtration. * In some instances, the filters as described in the various annual reports in connection with the purification of manufaetural wastes, bear different numbers than in this review. The numbers given here are for the sake of clearness and to prevent confusion.