Specification of Alexander Melville Clark : treating sewage, &c.

  • Clark, Alexander Melville.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: Specification of Alexander Melville Clark : treating sewage, &c. Source: Wellcome Collection.

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    2 A.D. 1872.—N° 388. Provisional Specification. Clarkes Improvements in Treating Sewage, ^c. phosphates are treated with dilute sulphuric acid, the reaction producing sulphate of lime and mono-calcic phosphate. An equivalent of sulphate of magnesia is then added, and after a double decomposition sulphate of lime is again formed and soluble mono-magnesian phosphate. After decanting and repeated washings the whole of the mono-magnesian 5 phosphate is eliminated. One equivalent of magnesia in paste is then added to the decanted liquor. This magnesia is produced by treating a solution of chloride of magnesia (mother waters of salt works) with its equivalent of milk of lime, according to the following reaction:— Mg cl + Ca. O. HO = Mg 0, HO + Ca cl. 10 The magnesia when added to the decanted liquor transforms the mono-magnesian phosphate contained in a state of solution into insoluble bi-magnesian phosphate by the following reaction:— Ph. 0® Mg, 02 HO + MgO, HO = Ph, O' 2MgO, HO. The bi-magnesian phosphate is recovered in a dry or pasty state. 15 This salt reacts directly and with great power on ammonia, which it fixes in the form of insoluble ammonio-magnesian phosphate, as indicated by the following formula:— Ph O' 2Mg OHO + AzW= Ph O' 2MgO Az, H^O. 2ndly. In order to produce calcio-magnesian phosphate the fossil 20 or other phosphates are treated with dilute sulphuric acid as before. The solution of mono-calcic phosphate thus obtained is then decanted, and to it is added an equivalent of magnesia produced in the manner above described, when the following reaction takes place :— Ph O' Ca 02 HO + MgO = Ph O' CaO MgO HO. 25 This new salt, viz., calcio-magnesian phosphate, acts in a similar manner to the bi-magnesian phosphate on ammonia, which it fixes in the form of ammonio-calcio-magnesian phosphate, thus,— Ph O' CaO MgO HO + Az = Ph O' CaO MgO Az H^ 0. In certain cases the bi-magnesian phosphate obtained in the manner 30 described is employed in a liquid state to act on ammoniacal waters, - said salt being readily soluble in a solution of chloride of magnesium (mother waters of salt works). This method is more particularly effica¬ cious for fixing the ammonia as it forms in sewage waters;