Travers. — Fighting Pollution in Ohio 289 



than it would live if put in water which has been boiled, and the oxygen 

 taken out in that way. 



The whole problem of coke beds, trickling filters, broken stone, etc, 

 is to allow thin layers of liquid to flow over large surface areas so that 

 bacterial life can go on and exhaust the food material in the waste, 

 obtaining the oxygen from the air with which it is in contact, and oxi- 

 dize or burn out the organic matter. Unless this is done the oxygen 

 must be supplied by the stream. 



This process, as I see it, is a precipitation process similar to iron 

 and lime. Of course, precipitation does not account for all wastes, 

 such, for instance, as you get from wood alcohol factories or the wood 

 distillation factories, which are toxic, and, though all suspended mate- 

 rials are precipitated, still contain deadly stuff in solution. All wastes 

 •differ and the problem of treating varies according to conditions. Even 

 where precipitation is all that is needed you have the sludge to get rid 

 of, and that is one of the biggest problems in connection with sewage 

 disposal. When the cost of manure is compared with the cost of drying 

 sludge, you find that it is a rather expensive process to take the water 

 out of a ton of sludge. Of course, you can take out some of the water 

 by centrifugal machines, but that is a fairly costly operation. The ques- 

 tion of sludge removal is quite a serious one. 



Mr. Barber : No more important matter confronts the Commission 

 of Conservation of Wisconsin than that of taking care of waste pro- 

 ducts from manufacturing plants. We have probably 40 paper mills, 

 sulphite plants, etc. We have been able to take care of the solid waste 

 matter, but the chemical waste is a problem that the state boards of 

 health are now working on. We find that the paper, sulphite, and other 

 mills are ready and willing to install any sort of system that is recom- 

 mended by the Conservation Commission. Now, Mr. Tulley, Sanitary 

 Engineer of the State Board of Health, recommends coke filtration. The 

 problem is that many of these plants have been constructed rather close 

 to the water's edge, and there is no room for the installation of a fil- 

 tration plant so that the water can filter through it from their mills. 

 May I ask Mr. Wells whether it is his opinion that the coke filtration is 

 practicable and will fill the bill? 



Mr. Wells : A great deal depends upon analysis. I do not doubt 

 that Mr. Tulley has complete results to justify his opinion in the case 

 you mention. The degree to which purification of a sewage is demanded 

 depends also upon the water into which it goes. First, the amount of 

 oxygen absorbed by a given amount of sewage is determined, and 

 second, the amount of oxygen in a given volume of water; we then 

 know whether the sewage will use up all the oxygen, or what percentage, 

 as the case may be. By knowing the necessary amount required for any 

 particular use of the water, the question of how much treatment is 

 necessary can be solved. The coke bed treatment is a rather thorough 

 treatment, though a more complete treatment is possible by passing the 

 water through sand beds, if the case demands it. Dr. Huntsman 



