WHAT IS A SEPTIC TANK?

Te Aroha News, Volume XXVII, Issue 43113, 4 July 1907, Page 4

WHAT IS A SEPTIC TANK?

[Since the erection of a septic tank at the Homes at Tararul and the Pafawai School, and in view of the fact that the Hospital authorities are very wisely following suit, the query “What is a septic tank?” ‘has been frequently [heard. Until very recently the process |by which decaying animal matter [gradually,., diisappears was little known land; less understood. It was known [that chemical changes occurred, but how, or why was beyond -the chemist’s power to explain. It is now, however, recognised that many of the chemical changes which take place in organic piatter are closely bound up with the life history of micro-organisms, either Lnimal or vegetable, general known as |nicrobes. . There is.no doubt that the lisappearance of solids from sewage passed into ; a stream is brought about |>y micro-organisms. These feed on Irganac matter and excrete it in a new lorm, its chemical composition as a lule being rendered simpler by the Iha-nge. As a general rule ea'eh species If micro-organism is poisoned or killll off by its own products ; but the Ife products of one species will generally ..serve as food for another. The B'eakmg down of the solids in sewage bus formls a long chain of operations, Bough often! ‘ accomplished in a. marfclously short space of time. In the Bjptic system no chemicals are employ--11, and there is *no “treatment” of the ■wage in the" ordinary sense of the Irm, its .purification being aoconiBished entirely by natural .agencies, ■he septic tank itself is merely a reBptacle designed te favour the multiBiCataon of micro-organisms, and Bing the whole of the sewerage under Beir influlence. To this end the tank Bof ample size, though hot larger than Build be necessary with .chemical preB>itation, and covered so as to exHde light, and, as far as possible air. He incoming sewage is delivered beH" the water level, and the outlet also ■submerged with the two-fold object ■trapping out air, and-'avoiding disHbance of -the upper part of the conHts of the tank. Oh entering the Hi. water of the tank the solids susHded in the sewage are to a great Hent disengaged, going either to the Htbm or to the surface, according to Hir Specific gravity. In -the absence H light and air the organisms ■finally present in the sewage in-Ht-se enoi-mously, and- rapidly attack j H the organic matter. By their ac-l ■ the more Complex organic sub-' ■•'ces are converted into simpler ■pounds, and these in turn are re- . H?d to still simpler forms, the ultiiHe products of the decomposition in. ! ■ tank being water, ammonia,, and 1

Bonia acid and! other gases. Other ■>genioUiS compounds may also be Bent, 'but they -will all ,be soluble ■ slightly alkaline solution, a eonwhich! obtains with every noiBliat has to he provided is a light. Hr atod, if possible, ail* receptacle, the influx and pipes have to he laid to the new law's of sanita.|B the structure has to be well and B&ly built—and marvellous Nature rest!