Specification of Francis Gerard Prange and William Whitthread : utilizing sewage.

  • Prange, Francis Gerard.
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Francis Gerard Prange and William Whitthread : utilizing sewage. Source: Wellcome Collection.

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    JPrange 8f Whitthread’s Improvements in Utilizing Sewage. The proportion in which the chemical substances are added will vary with the quantity of nitrogenous and fertilizing matters contained in the sewage, and also as it may he desired to render the effluent treated sewage water more or less clear and sweet. If the effluent treated sewage water is to pass into a stream or into the sea a larger quantity 5 will he added than in cases where the water is to be used for irrigation, hut we would have it understood that the application of the said chemical substances in any and every proportion is beneficial both in respect of deodorizing the water and of precipitating and fixing the fertilizing matters. 10 When a sufficient quantity of the fertilizing matters have been carried down in the depositing enclosures or in the settling tanks the water is run off and the fertilizing precipitate collected and used, either in the pasty state or dried, so as to be convenient for transportation. In carrying our Invention into practice we prefer when the effluent 15 treated water is not to be used for fertilizing purposes by irrigation, to proceed as follows :—We treat one equivalent of tricalcic phosphate with two equivalents of sulphuric acid. The resulting mass from that treat¬ ment will consist of a mixture of one equivalent of mono-phosphate, two equivalents of calcic sulphate, and such impurities as are contained 20 in the materials used. We next add by weight three parts of the above mono-calcic phosphate and impurities to one part of tricalcic phosphate and water in sufficient quantity to form a thin paste. The mono- calcic phosphate reacts upon the tricalcic phosphate and forms di-calcic phosphate which is held in solution by the excess of mono-calcic 25 phosphate. The solution obtained as described is added to the liquid sewage in such quantity as shall produce a faint acid reaction. The said reaction having been obtained hydrate of lime is added in such quantity as shall cause precipitation of nitrogenous and manurial matters contained in 30 the sewage. In all cases care must be taken not to add more lime than is necessary to effect precipitation. When the effluent water is to be used for fertilizing by or during irrigation, we add a less quantity of the solution of mono and di-calcic phosphates. 35 Although we prefer to allow the sewage treated as above described to