| 摘要 |
<p>PURPOSE:To control the amounts of incoming sewage and returned sludge on the basis of the set value or MLSS (activated sludge microorganism concentration), the amount of incoming sewage, and the total amount of sludge for keeping MLSS of a specific circuit constant in an aeration tank operated by a step aeration method. CONSTITUTION:A signal of MLSS of the circuit A is put in the MLSS regulator 8, and the output of the regulator 8 is added the incoming sewage amount Qia* of the circuit A for keeping the set MLSS values Ca* and Cb* at inlets of both the circuits A and B in order to operate the inflow door 2, thereby the amount of sewage to the circuit A is controlled. Also, MLSS value Cb at the inlet of the circuit B is put in the regulator 7, and the output of the regulator 7 is added to the returned sludge amount Qr* for keeping the set MLSS values Ca* and Cb* at the inlets of both the circuits A and B at an average valve in order to operate the valve 3, thereby the amount of returned sludge is controlled. Accordingly, MLSS can be kept at set values with good responsiveness for a long length of time even when the gain of the regulator for both the circuits A and B is made small to some extent for avoiding interferencial phenomenon.</p> |
