Specification of Henry Young Darracott Scott : treating sewage water.

  • Scott, H. Y. D.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Henry Young Darracott Scott : treating sewage water. Source: Wellcome Collection.

    4/14 (page 2)
    Provisional Scott’s Improvements in Treating Sewage Water. purification of sewage water than can be brought about by a single precipitation process. In carrying out my Invention I commence by removing from the sewage the grosser foeeal matters and impurities, and for this purpose I prefer the method of precipitation by lime. I then agitate with the 5 effluent water from such precipitated matters hydrated phosphate of magnesia, which when allowed to subside will carry down with it, in chemical combination the ammonia contained in the sewage water, and with which ammonia the phosphate comes into contact. When excess of lime has been used in the preliminary precipitation of 10 the grosser foeeal matters, phosphoric acid in some soluble combination, such as in the form of a phosphate, may be employed to separate the free lime from the liquid before the phosphate of magnesia is added, or the other and soluble phosphate may be added simultaneously with the introduction of the insoluble phosphate of magnesia. 15 When the insoluble compounds (formed by the action of their phos¬ phates) have settled, the supernatant liquid is to be drawn off, and these solid compounds are collected, dried, and exposed to heat in order to expel the ammonia which has been absorbed, and which may after expulsion be collected by well known chemical methods. Or the com- 20 pounds may be carefully dried and sent into the market as manure. As hydrated phosphate of magnesia is not perfectly insoluble some of this substance will be carried away in the effluent water and be lost, unless the water be applied to irrigation purposes; I therefore some¬ times add to it a sufficient quantity of milk of lime to precipitate the 25 phosphoric acid dissolved in the water. When I can obtain the calcareous substances containing both carbonic acid and phosphoric acid in considerable proportions I calcine such sub¬ stances, and having dissolved out the lime, I employ the lime for the preliminary precipitation of the grosser foeeal matters of the sewage, 30 and I use the phosphate of lime (which remains undissolved in the water) for the preparation of the phosphate of magnesia required for the collection of the ammonia.