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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    Precipitation ivith Lime. — In one of the processes at the tannery a large amount of lime was used, and milk of lime was being mixed almost continuously with the rest of the waste. Experiments soon showed that 60 per cent, of the- organic matter could be removed by sedimenta- tion with the aid of this lime waste. The resulting supernatant liquor, still very rich in organic matter in solution, was first applied in January, 1.896, to a filter }4oooo of an acre in area and containing 4 feet in depth of sand of an effective size of 0.14 millimeter. This filter was located in a building in which the temperature was but slightly above the freezing point during the winter, and, because of this low temperature, nitrifica- tion did not become active until the approach of warm weather. The waste was applied for four months at the rate of 120,000 gallons per acre daily, but this rate was found to be excessive for so strong a sewage, and was reduced to 60,000 and then to 30,000 gallons per acre daily. Nitrification began in May, 1896, and the filter was continued in opera- tion until September, 1898. Nitrification continued active; the effluent from the filter was clear and colorless, and when the filter was discontin- ued it was working satisfactorily, and gave promise of doing so indefi- nitely. The following table gives the average analysis of the liquor applied to and of the effluent from this filter: — Average Analysis of Tannery Sewage applied to Filter. [Parts per 100,000.] Ammonia. Chlorine. Nitrogen as — Oxygen Consumed. Fats. Free. ALBUMINOID. Total. In Solution. Nitrates. Nitrites. 6.82 2.39 1.83 375 0.17 .0112 46.66 8.97 Average Analysis of Effluent from Filter. 1.45 0.23 0.12 405 9.96 .0258 1.79 6.00 A third filter, constructed of 4 feet in depth of sand and receiving a mixture of the tannery liquor and domestic sewage, was kept in opera- tion from June, 1896, until the beginning of 1898. During most of this period the mixture had the proportions of 1 part tannery liquor to 2 parts sewage, and was applied to the filter at rates between 40,000 and 50,000 gallons per acre daily, with satisfactory purification. Cole Strainer. — A coke strainer, containing 2 feet in depth of coke, the upper portion being coke breeze and the lower portion coarser coke.