BIOLOGICAL WATER TREATMENT EQUIPMENT

PROBLEM TO BE SOLVED: To secure high quality water by properly controlling the quantity of a flocculant or acetic acid to be added to a biological water treatment equipment to constantly efficiently remove a phosphorus component in sewage water. SOLUTION: The biological water treatment equipment has a water injecting pump 9 for adding a chemical into a biological reaction vessel 1 to which sewage water flows in, an aeration apparatus 4 attached to the biological reaction vessel 1, a settling pond 5 for settling a mixed liquid flowing out from the biological reaction vessel 1, a return sludge pump 7 for returning settled sludge to the biological reaction vessel 1 and an excess sludge taking out pump 6 for taking out the settled excess sludge. When at least one of the quantity of aeration by the aeration apparatus 4, the quantity of the sludge returned by the return sludge pump 7 and the quantity of the taken out excess sludge taken out by the excess sludge taking out pump 6 reaches the upper limit or the lower limit, a chemical addition starting signal is output. COPYRIGHT: (C)2007,JPO&INPIT