Specification of Dugald Campbell : treating sewage, &c.

  • Campbell, Dugald.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Dugald Campbell : treating sewage, &c. Source: Wellcome Collection.

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    Campbell's Improved Process for Treating Sewage, fyc. procurable, a milk or cream of magnesia and lime prepared from mag¬ nesian limestone in quantity sufficient to neutralize the acid which was. in the acid phosphate of lime added to the sewage. In carrying out my Invention of “An Improved Process for the Treatment of Sewage and the Production of Manures therefrom,” by 5 the use of artificial or manufactured phosphates of lime rendered soluble by acid or acids, I prefer to use the material obtained from the calci¬ nation of bones, known in the market as bone ash, as it is at present the cheapest and best source with which I am acquainted from which I can now derive by the treatment of an ordinary mineral acid a soluble 10 phosphate of lime as free or as nearly free as it is possible commercially to obtain it from the phosphate of alumina or the phosphate of iron, and to this bone ash I add about three-quarters of its weight of . sulphuric acid, by preference of brown sulphuric acid, made from pyrites of 80 per cent, as the most economical, mixing or stirring up the whole 15 well together, and allowing the mixture, preferably, to remain undis¬ turbed for a few hours, wdien the mixture described can be most advantageously used either in its then existing state or preferably dissolved in water or in sewage or any analogous liquid; this solution of soluble phosphate of lime is then to be mixed with the sewage 20 to be treated, contained in a cistern or reservoir, by means of agitators of any ordinary kind in the said cistern or reservoir, after which the milk or cream of lime, or of magnesia and lime prepared from mag¬ nesian limestone, sufficient to neutralize the acid which was in the acid phosphate of lime added to the sewage, is added and the whole com- 25 pound mixture is to be well agitated and then allowed to rest until the precipitate having subsided (which it will shortly do), the supernatant liquid is run off from it, and where practicable such supernatant liquid is applied to the irrigation of land, to which purpose it will be found highly beneficial. 30 Instead of adding the solution of acid phosphate of lime to the sewage in a cistern or reservoir, and agitating the mixture and afterwards adding the milk or cream of lime or of magnesia and lime, and again agitating the solution of acid, phosphate of lime may be run into the upper part of an inclined trough containing the sewage, so as to produce 35 a running stream of the sewage and solution of acid phosphate of lime mixed together. The milk or cream of lime or of magnesia and lime is then to be delivered at a lower part of the trough into the stream