Waterbury Democrat., 1902-04-22
SEWER COMMISSIONS REPORT.
Pamphlet of Thirty-two Pages Has
 Just Been Issued.

|
 Just Been Issued. The third report of the state sewer age commission, a. pamphlet or 5z pages, has just been issued. The flrst four pages are taken up with letter of transmittal, reciting the re-organl- Zation of the commission under the law passed at the January session or 1901, the objects aimed at in the work
 of the commission, and the difficulties
 encountered due to lack of funds for
 carrying on experimental work. This
 is followed by a statement in regard 1 to the work which has been carried on
 for some time by Professor Kinnicutt l of Worcester, the results of which
 were given to the commission and which it was believed would be so
 useful to parties installing bacterial purification plants as to warrant their publication as a substantial contribu- tion to the worlds knowledge of the
 subject.
 These experiments were made to as- certain exactly what it is that takes place in the septic tank, that feature of sewage disposal works which has been so much discussed of late and in regard to which SO little can be said I to be positively understood. The sewerage treated was the or dinary city sewage of Worcester. A small tank was carefully arranged and all the details for management, observation and testing were most mi nutely provided for. A great num- Der of exact analyses were made at stated intervals, showing the compost | tion of the sewage, of the gases 1 evolved, the surface crust or scum, and of the slEdge deposited at the bottom of the tank. Average results are giv- en, showing the effect of the process in reducing the amount of suspended | matter i'll the sewage, the evolution of gas and its composition, and the change of chemical composition be- tween the crude sewage and the eff1u- 1 ent from the tank. These matters are treated in a very thorough man l ner, with great attention to detail and this part of the report will repay care | ful study by those professionally con- cerned in the design and installation of sewage disposal plants of which the septic tank is to be q feature The results so far obtained are thought to point to the following con- clusions
 That about one-fourth of the total solid matter is removed by the passage of the sewage through q septic tank That the amount of soluble matter removed, equalling i'll Worcester about 7 per cent. of the total soluble matter is greater than the amount usually found to be removed from a sewage by septic tank action.
 That the amount of suspended mat ter removed, found to be about o5 per cent of the total suspended matter, is very much less than the amount re- moved by the same process from sewage containing less manufacturing waste
 That the above results are due to the change of the soluble sulDhate of iron in the sewage into the insoluble sulpnide of iron, and to the fact that comparatively large amount of iron sulphide is carried out of a septic tank in the euent.
 That the action of q septic tank re moves q large amount of iron from an acid iron sewage.
 That the amount of organic matter removed, 26 per cent in Worcester sewage, is much less than is removed by the same process from an alkaline domestic sewage.
 That though greater amount of organic matter seems to be removed from the sewage in the warm months than in the cold months, the results possible, owing to methods of sampling show no direct relationship between the organic matter removed and the temperature.
 That the amount of gas given off depends greatly upon the amount and character of the sludge at the bottom of tank. and the amount given off is measure of the total amount of bac- terial action taking place. and is not measure of the amount of organic matter being removed at any given time from the sewage.
 That the amount of gas evolved from q septic tank depends upon the temperature and that it is less in win ter than ill summer.
 That the amount of gas evolved from the septic tank at Worcester. for the past year, 2.2 gallons per 100 gal Ions of sewage passing through the tank, is probably less than would be obtained from q tank where the sludge contains q greater amount of organic matter.
 < Astl ldC gus SlNt1 OIL lEOIH d LaDk through which acid iron sewage is passing is a mixture of methane. nj trogen and carbon dioxide; containing little, if any, hydrogen
 That the amount of sludge changed into soluble or gaseous substances, 28 per cent with the Worcester Sewage. is ! probably less than would usually be the case, on account of the large amount of iron sulphide in the sIudge.
 That the sludge in q septic tank con- talns less organic matter in the au- tumn than in the spring.
 That the crust contains much lar ger amount of organic matter than the sludge.
 That the formation. non-formation, and disappearance of the crust on top of the liquid in q septic tank appears to be an incident rather than result of bacterial action.