Mr. Powell. You sell this stuff for $20 a ton?
Mr. Hatton. No; $15.
Mr. Powell. What does it cost to put it in a salable condition after it is taken out?
Mr. Hatton. Six dollars a ton.
Mr. Powell. You have a profit of $9 a ton?
Mr. Hatton. Approximately $9 a ton. You understand the ammoniacal nitrogen varies, of course, and that cost is based upon the ammoniacal nitrogen, and our average is 5 per cent so far. In wintertime I imagine it will grow less. In July, August, and September it will grow more. It is true we have a very strong sewage, containing, for the last month, for instance, 369 parts of suspended matter. That is a good deal stronger than the average municipal sewage. It is industrial sewage, largely. Now, I do not want you to think these samples I am showing you are picked out samples. These are samples which a good many gentlemen present will tell you they have seen in our plant that they have visited day by day. This was taken yesterday at noon and delivered to me in the afternoon. This is a bottle of the raw sewage, after passing through the half-inch screen. I am now showing you a bottle of the sewage taken from the aerating tanks, containing about 25 per cent of activated sludge, the nitrifying media which purifies the sewage, and I am now showing you the effluent passing away from the sedimentation tank 4 hours and 45 minutes after it passed into the influent tank. So far as we can determine, there is a trace of suspended matter in that sewage. Of course we could not determine whether it was stable or not, because that takes time. It was taken out yesterday, but my chief chemist, who brought the samples to me, told me there was no doubt about the stability of that liquor.
Mr. Mignault. Have you analyzed it to determine whether there subsists a certain amount of B. coli?
Mr. Hatton. No; this was taken yesterday; but we do get some B. coli; we do not get complete sterilization. We attempt to get 95 per cent reduction of bacteria in our effluent. We have not had occasion yet, except when our plant was broken down, or the lake was so high that it backed into our plant, to reduce our standard. We could always get 95 per cent, and we more often got 98 or 99 per cent. I do not know whether I should show you this box I have here very closely, because it does not smell very well.
Mr. Tawney. You do not deodorize your sludge?
Mr. Hatton. No. I am showing you now a sample of the pressed sludge.