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.

    6/14 (page 4)
    Scott’s Improvements in Treating Seivage Water. The improved method whereby this is effected has the collateral advantage of yielding phosphates of alkaline earths in a condition very suitable for agricultural purposes. It also effects a further and more complete purification of sewage than can be brought about by a single precipitation. 5 In carrying out my Invention I commence by removing from the liquid to be treated all the grosser foecal matters and suspended impuri¬ ties, and for this purpose I prefer the method of precipitation by lime. I also prefer to make use of dolomitic lime in lien of pure or ordinary lime. Out of the dolomitic lime I first dissolve the lime by means of 10 clarified sewage water, and I then mix the solution of lime so obtained with the sewage to be precipitated. I employ the magnesia which remains undissolved in the liquid for the preparation of the phosphate of magnesia, which I subsequently use for the extraction pf the ammonia from the polluted or sewage waters. 15 I sometimes employ for the preliminary precipitation of sewage calcined calcareous phosphatic minerals, out of which I dissolve the lime in the same manner as I practice with the dolomitic lime for the removal of its grosser foecal matters, whilst the undissolved phosphates are made available for the supply of the phosphoric acid in the pre- 20 paration of the said phosphate of magnesia. With the view of facilitating the separation of the lime from the phosphates of such minerals I sometimes intimately incorporate with them (previous to their calcination) a sufficiency of lime to produce slaking in the calcined compound. 25 In any case, whether ordinary lime be employed or whether mag¬ nesian lime or phosphatic lime be used as the source of supply of the lime with which the sewage is clarified, the precipitate so obtained is allowed to deposit in a tank or tanks, which I will call No. 1. This deposit may be calcined and converted into cement or agricultural lime 30 according to methods now in use, or it may be mixed with town ashes and employed as manure, or it may be converted into charcoal and be used for the filtration of the sewage or for other purposes. In cases in which straining or subsidence are employed for the removal of the grosser foecal matters it is still advantageous to use some process of 35 precipitation before applying the phosphate of magnesia, with which I