SE378587

1346467 Treating waste liquor STERLING DRUG Inc 10 June 1971 [22 June 1970] 19954/71 Heading C1C A process for treating a liquor obtained by dewatering a thermally conditioned sludge, in a system comprises feeding the liquor at a rate between 1 and 5 kg. BOD 5 per day per kg. mixed liquor solids through an aeration vessel containing activated sludge, where it is agitated for at least two hours with oxygen-containing gas (e.g. air) at 25-40‹ C., to a settling tank, recycling settled sludge to the aeration vessel and removing sludge from the system at approximately the same rate as it is accumulated in the aeration vessel. The sludge concentration in the aeration vessel is kept approximately constant. Monobasic potassium phosphate may be added to the aeration vessel. The liquor may be heated by passing in indirect heat exchange with thermally conditioned sludge or by an electric heater or steam coils associated with the aeration vessel. The liquor may be obtained from a heat treated or wet air oxidized sludge.