Specification of William White : treating sewage.

  • White, William.
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Specification of William White : treating sewage. Source: Wellcome Collection.

    6/10 (page 4)
    White's Improvements in Treating Sewage. The sewage or cesspool water, or water from urinals being conveyed into suitable settling tanks, I ascertain the quantity of sulphates, car¬ bonates, and phosphates present, and whether there be any free acid; if so I neutralize with milk of lime. I then thoroughly mix with the same a sufficiency of chloride of calcium to precipitate the sulphates, car- 5 bonates, and phosphates therein; the precipitate thus formed dragging down a large proportion of the albuminous and other organic and nitrogenous matter in suspension and solution, and forming a valuable manure. The solution of chloride of calcium is, by preference, thrown over the surface of the sewage by a pump forcing the solution through a 10 rose. In order to produce a larger body of precipitate and thus carry down a still greater proportion of albuminous and other matter, I introduce an excess of chloride of calcium, and subsequently add to such mixture of sewage or cesspool water, or water from urinals, and chloride of calcium, 15 sulphate of iron, either in solution or otherwise, by which means the excess of chloride of calcium may be converted into sulphate, setting chloride of iron free, which chloride is well known for its astringent action on organic or albuminous matter. The chloride of iron also by oxidation and combination with such organic matter becomes to a great 20 extent gradually converted into an insoluble precipitate. In order however to remove more rapidly any excess of chloride of iron I precipitate the iron as oxide by the addition of a sufficient quantity of lime; I thus secure a series of three distinct precipitations, each capable of carrying down organic matter; the first being effected 25 with chloride of calcium, the second with sulphate of iron, and the third with lime, leaving a small residue of chloride of calcium in solution. It is preferred that the quantity of chloride of calcium employed should be such that these precipitates should amount at least to 15 grammes per gallon. In some cases, especially when it is desirable to fortify the 30 manure obtained with additional phosphate, I produce a very copious precipitate by dissolving bones, bone ash, horny substances, or minerals containing a considerable per centage of phosphate of calcium in hydro¬ chloric acid, and use the mixed solution of phosphate and chloride of calcium for precipitation, introducing to the tank sufficient milk of lime 35 to neutralize any excess of acid, and to ensure the precipitation of the whole of the calcic phosphate. The supernatant water may then after sufficient repose be drawn off, and if still greater purity be required be