Sewage utilisation / edited by James Forrest.

Date:
1876
Catalogue details

Licence: Public Domain Mark

Credit: Sewage utilisation / edited by James Forrest. Source: Wellcome Collection.

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    CO phate originally added to the sewage as contained in the manure deposited; but if this was compared with column D, the actual cost of that same phosphate, as stated in the Paper, it appeared that the process of dissolving the phosphate in the sewage and depositing it had increased its value, in the first experiment 52 per cent., in the second 21 per cent., and in the third 62 per cent.; the mean of the four experiments being 30 per cent. It did not appear that this increased value arose from an increase in the quantity of the phosphate, but rather from the higher value per unit assigned to it. For instance, in the third experiment, 32 lbs. of phosphate were used, costing Is. 5d., whereas the phosphate obtained was barely 18 lbs. and was valued at 2s. Id., or an increase of more than three times its value by manipulation. Now con- sidering that the phosphate contained in these manures was com- bined with from 66 to 80 per cent, of what had been significantly designated ‘ profligate associates,’ he could not but think that the value of 3s. 3d. per unit did not express the true money value to the farmer of the phosphates contained in the manure derived from sewage, and that the mode of estimation adopted was likely to lead to fallacious results. Mr. C. E. Austin observed that for the last ten years he had advo- cated a system of extracting the solid matter from the sewage at the earliest possible moment, collecting it in the branch drains, and not allowing it to go into the main sewer. This he had suggested might be accomplished by strainers changed and removed daily from the drains, and conveyed to a market garden, or some other place where the solid could be used as manure. This plan was adopted by a seaside colony commencing building, and, having been in work for the last nine years, had given satisfaction, and was now to be extended over the whole district within the jurisdiction of that Improvement Com- mission. He need not mention the difficulties of promoting a system of that sort, but having tried experiments with this system in two or three other places, no objections had been raised to the results. In one case, where it was tried for a year and a half in a town on the Thames, and where the analyses both of the sewage aud the effluent waters were regularly published, although it gave perfect satisfaction, the local authorities finally abandoned it, and said, “ If we adopt your system we shall have to pay for it. and afterwards we shall havo to pay for the Government system, for a combined system of drainage was being held over them in terrorem. The process was a cheap one, costing only 2per head for a population exceeding five thousand, and the solid matter