PROFITABLE SANITATION.

Taranaki Herald, Volume LV, Issue 13983, 14 August 1909, Page 6

PROFITABLE SANITATION.

- The problem of the disposal of sewage is solved by most cities m an unprofitable and irrational manner, but there is little doubt that in the near future every progressive town will be converting the waste into profit. Dr. Grossman, of Manrhrstor, has lately published particulars of a scheme by which sewage can be made to yield up valuable products. He computes that in England alone 400,000 tons of soap are used .every year, practically all of which finds its %ray into the sewers. It is from the recovery of the valuable fatty acids contained' in the soap that Dr. Grossman plans to derive part of the revenue to be produced by his process. The other part is obtained from the residue, which possesses considerable manurial value and can be stored or used en land without creating a nuisance. This residue is yielded in the fornf of a dry powder. The process is comparatively simple. Tho sowage- sludge is dried by heat, mixed with a little acid, and passed through a specially-designed retort, in which it is subjected to a current of superheated steam. Tho steam carries away with it the fatty acids, which are condensed in a tower, and carried to a tank at the bottom by constantly running streams of water. The residue is retained in tho retort, and when drawn off is dried and converted into a powder, suitable for spreading on land. It is rich in nitrogen and in organic compounds. The condensed fat collects on the surface of the tank. It can be easily and cheaply purified, yielding a grease rich in stearic acid, which is a valuable article of commerce. Dr. Grossman estimates the average profit for a town of 100,000 inhabitants at about £4600 per annum. A large experimental installation which has been intermittently working at the Oldham Corporation sewage works for the last twelve months is now in process of being extended and converted to continuous work.