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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    Removal of Arsenic by Coke and Iron. — Methods for removing the arsenic from this tannery sewage were studied, and it was found, as stated previously, that by passing the sewage through a filter or strainer of coke breeze it was quite thoroughly freed from arsenic. This removal was due probably to the presence of iron in the coke, since the same result was accomplished by passing the sewage through iron filings or turnings. Average Amount of Arsenic (Ms203) in Entire and Supernatant Sewage, and Effluent from Coke Strainer. [Parts per 100,000.] Entire tannery sewage, 8.5447 Supernatant tannery sewage, 1.6757 Effluent from coke strainer, ......... 0.0823 Generally speaking, the effluent from the coke strainer was free from arsenic, but occasionally, if an excessive amount was applied and if the strainer was overworked, some arsenic would pass through. Examination of the coke proved that a large percentage of the arsenic was retained in the upper few inches of the strainer. For example, a small strainer con- taining 2 feet in depth of coke breeze was flooded each day for two weeks with this sewage. The effluent examined each day was found to be free from arsenic. On October 15 the coke itself was examined, with the fol- lowing results: — Arsenic as AS2O3. [Parts per 100,000.] Upper 4 inches of coke, 36.40 Middle 4 inches of coke, 6.60 Lower 4 inches of coke, 0.20 The investigations upon the wastes from this tannery are fully described in the report of the Board for 1896, pp. 431-433; and in the report for 1897, pp. 396 and 397. Tannery Cf In 1900 an application was received by the Board from a tannery, asking advice as regards the improvement of its wastes and stating that for years a system of settling basins had been maintained at considerable expense. The following conditions were found to obtain at this tannery: the chief waste liquors were those from the processes of wool-scouring, skin-wash- ing, tanning, dyeing and the drainage from the water-closets used by about 300 employees, all of these wastes passing to the settling basins. The water used in the last bowl of the wool-scouring machine was discharged into a stream in wet weather, but when the flow was small this water was