Specification of John Leigh : treating sewage.

  • Leigh, John.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: Specification of John Leigh : treating sewage. Source: Wellcome Collection.

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    Leigh's Improved Mode of Treating Sewage, 8fe. thereby, or by other matters held in mechanical suspension by adding thereto and agitating therewith in suitable tanks, vessels, or receptacles, a solution of an earthy salt, followed by a solution of silicate of soda or of potash, whereby a precipitation or subsidence of the suspended 5 matters in the sewage or other waters is produced. Of the earthy salts I prefer to use a solution of alum or of sulphate of alumina, of sulphate or of muriate of magnesia, or of muriate of lime. Should the sewage or other contaminated water after being thus 10 treated contain any gelatinous or albuminous matters in solution, or afford evidence of other organic matter in solution, I add thereto a small quantity of a solution of tannin, or of some solution containing tannin. As the sewage and other contaminated waters will vary from time to 15 time in consistence and degree of dilution, so also will the quantity of earthy salts and of alkaline silicates that may be required to produce complete precipitation of the suspended matters. The sewage or other contaminated waters to be treated may be received in suitable tanks, receptacles, or reservoirs, and thereto added a solution 20 of alum, whether potash alum, soda alum, or ammonia alum, in such proportion that a quantity, equivalent to two grains, and increasing from that to ten grains for each gallon of sewage shall be added, or a quantity of solution of muriate of lime, equivalent to one grain, and increasing from that to seven grains for each gallon of sewage, or of a solution of 25 sulphate of magnesia, which shall hold dissolved from one grain to eight grains of the crystallised sulphate for each gallon of sewage. Tor the alums may be substituted the sulphate of alumina, prepared com¬ mercially on a large scale for use in dyeing, by treating pure clay with strong sulphuric acid. When this is used a somewhat smaller quantity 30 will be required. After any of these earthy salts have been added to the sewage or other waters proposed to be treated, and well mixed therewith, a solution of silicate of soda or of silicate of potash is to be added, by which an insoluble earthy silicate will be formed, and this in its fall through the 35 liquid will carry with it to the bottom of the tank or vessel such matters as may have been held in suspension in the liquid.