The sewage problem in villages and small towns / by Gilbert Thomson.

  • Thomson, Gilbert.
Date:
[1892]
Catalogue details

Licence: Public Domain Mark

Credit: The sewage problem in villages and small towns / by Gilbert Thomson. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    10/14 (page 8)
    Besides the impurities which a chemist can detect, we may have, and must always assume that we have in any given specimen of sewage, the germs of specific disease. The definition of dirt matter in the wrong place, is, of all things, true of sewage! Its constituents could be applied to the ground, not only without harm, but with great advantage; and the mixture of this valuable manure with the water produces a most dangerous and worthless substance. If the two could be separated both would be valuable, but it is in the separation that the difficulty lies. When the question of sewage disposal first became urgent, the manurial value of sewage matters was fully realised, and great fortunes were looked for by individuals, and great profits by communities, in utilising this waste product. After many costly experiments, most of them more or less failures, the dream of boundless wealth to be derived from sewage was slowly abandoned, and those towns which could solve the difficulty by the simple means of running the sewage into the sea came to be envied, as being able, at least, to dispose of their sewage without loss. In other cases, given the sewage, we may do one of tAvo things with it. We may purify it thoroughly, or we may purify it partially. In the former case it will be costly; in the latter, with favourable conditions, it may be profitable. It is an easy matter to take some of the pollution out of the water, but the difficulty increases as the proportion to be removed increases. It is not the first, but the last, step that costs. If the purification must be pushed to a degree at which the effluent water may be considered harmless, the financial result will most probably be on the wrong side. Certain places, no doubt, Avith exceptionally favourable circumstances and careful manage- ment, may be able to shoAv a balance of profit, but the margin is an extremely narroAv one, and has a strong tendency to convert itself into a loss. Where purification is a secondary matter, and profit the first, there is no doubt that pi'ofit can be renlised, as in the well-known example of the Oraigentinny meadows, where very inferior land, drenched with sewage, produces immense crops; but fcAv toAvns are in that happy position, and it is Avith the cases Avhere purifi- cation comes first that Ave are chiefly concerned. The first stumbling-block in the Avay of sewage purification is the difficulty of convincing the popular mind that apparent and real purification are tAvo difl^rent things. I know that by referring to the difference between precipitation and purification, I am