The Bridgeport evening farmer., 1911-06-02
SEWAGE PURIFICATTON
Il Remarkable Results Attained by Mod ern Filtration Methods-RepOrt by United States GeolOg-
 ical Survey

As the population of cities and towns becomes more and more con- gested, the public health requires that some methods be adopted that will change the chemical composition of the sewage so that it will not pu- trefy when discharged into water courses. In some places it is even necessary to disinfect the sewage so troyed. Disinfection is demanded because of the possible pollution of water supplies and of shallfiSh beds. The methods adopted for sewage dis infection are described at length in a publication issued by the United States Geological Survey as Water Supply Paper 229, entitled "The Dis1n- lection of Sewage and Sewage Filter Effluents." by Earle P. Phelps
 Sewage purification as practiced to- day is but the artificial and intensive application of the process used every where by nature to reduce putresci- ble organic matter to inert inorganic matter. It is well known that if any organic matter such as garbage a dead animal is left exposed up- on the ground, 1t putrefies or rots for a considerable period, giving off nau- seous odors in the meantime. After 9. while the rotting is complete, the odor disappears, and the material be- comes mineral matter exclusively. The process Is scientifically defined by saying that the organic matter has become oxidized, that is, oxygen has united with the organic matter to produce the desired result The pro- cess of sewage purifcation is precise " the same except that in the purifi- cation work conditions are provided under which nature is assisted in her work and the result is accom- plished in a much shorter space of time.
 Great Capacity of Improved Filters
 The improvements made in meth ods of treating sewage have therefore not involved the discovery or applica- ton of new principles; those eStab- lished since the world began are util- ized The constant aim of the ex- perime nters has been - increase the rate at which sewage can be purified From the old-time sewage irrigation field. with its maximum capacity Of purifying possibly 10000 gallons of sewage on an acre in 24 hours, to the present-day trickling filter capable of dealing with two or three million gallons a day on an acre of filter sur face. the march of improvement has been steady and continuous.
 The later investigators have found that efficient purificatiOn can be ac- complished without carrying the pro- cess to the point of complete oxida- ton. The liquid flowing from a modern trickling filter, according to Mir. Phelps, looks to the untrained eye like the original sewage; indeed, there is almo g much organic mat ter in the effluent as in the raw sew age, and sometimes more, but this organic matter has been sufficiently changed or oxidiZed to rob it of it's foulness. In other words, it's chem icai composition has been so altered that it is no longer capable of under going rapid putrefactive decomposi- ton.
 Although it may appear inconceiv- able that the chief object of sewa4e puriflcation-preventi of the frNs- ing of streams-can be attained by such invisible changes in the nature of the organic matter. neverthe1es the discharge from efficient sewage-dis- posal plants may be permitted to en- ter a stream without fear of causing nuisance. The work of purifca- tion also proceeds in the stream itself as It does in the soil and in the pu- rlhcat1on works, until the oxidation Is complete. Oxygen for that pur- pose is sufficiently abundant in a req sonably clean stream, but if the