Mr. Rich. Not any more than our general reading of the subject. We have not made any studies of local conditions. Sludge obtained from fine screening would probably need to be disposed of by incineration or else taken to a long distance from the city and buried; but probably that would be too much for the city of Detroit.
Mr. Powell. The city of London has installed, and the city of Glasgow, Scotland, was about to install when the war broke out, a system which makes it a decided success from an economical standpoint. They produce a lot of chemicals from the sludge. You have not given any attention to that?
Mr. Rich. You do not know what they produce?
Mr. Powell. Yes; some of the things they produce are gasoline, carbolic acid, and a pitch. I think there are nine by-products that they dispose of.
Mr. Rich. No; I am not familiar with the details of that.
Mr. Tawney. I understand you to say, Mr. Rich, that, while you have read the different alternative plans or remedies proposed by our consulting sanitary engineer, you have not given them sufficient study to determine what, in your judgment, would be the most desirable and the most economical in practice?
Mr. Rich. No; I do not think so.
Mr. Tawney. You do not desire to express an opinion on either one of them?
Mr. Rich. Only that I think we would be justified in saying that we believe the tankage method, followed by sterilization, would be superior to screening methods.
Mr. Mignault. That is, you prefer the process of sedimentation to that of fine screening?