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.

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    Scott’s Improvements in Treating Seivage JVater. nesia, or through a mixture of this salt and animal or other charcoal, or I may use a filter of animal or other heavy charcoal, as the bottoms of tanks No. 3, 3a, 3b, and by keeping the phosphate of magnesia in sus¬ pension in the liquid above allow the liquid to filter through the bottom instead of being drawn off at the top. 5 Again, in lieu of stirring the phosphate of magnesia in with the liquid, I may keep it in a state of suspension in the liquid, by pumping air into the tanks, and I may also keep it in suspension by allowing the clarified liquid to rise from the bottom upwards and flow over the top. By properly regulating the depth of the tanks, the flow of liquid, and the 10 amount of phosphate of magnesia, I may even render the process con¬ tinuous ; hut I have found this and the other processes above mentioned less easy to carry out than the first described process where ordinary subsidence is employed for the separation of the liquid from the deposits obtained. 15 In cases in which there is difficulty in arranging for so great a number of tanks I may combine the first and second precipitations by adding, first, the lime to the sewage as it flows through the sewer, and then, when this has had time to act, by adding also in the trough which conveys the sewage to the first settling tank the phosphoric acid or 20 soluable phosphate to precipitate the lime still remaining in solution, or I may introduce the soluble phosphate into the conduit which leads to the phosphate of magnesia tank, and allow the phosphate of lime to settle in it with the magnesian salts; or again, I may dispense altogether with the operations to be performed in No. 4, hut at the cost of losing some 25 of the phosphate of magnesia. Again, in lieu of introducing into tanks 3, 3a, &c., phosphate of mag¬ nesia as such, I may make use in the tanks themselves of substances which will by combination form this salt; for instance, I may from time to time put into tank No. 2, or into the channel that leads to it, an 30 excess of superphosphate, such as superphosphate of magnesia, and allow the liquid so charged to pass into tank 3, 3a, &c., to be there agitated with a large quantity of magnesia to be used by preference in the hydrated state. The result of this treatment will be the production of phosphate of magnesia in a condition to combine with the ammonia of 35 the liquid, either when the phosphate is in process of formation, or sub¬ sequently to its formation, on coming into contact with it.