| 摘要 |
PROBLEM TO BE SOLVED: To suppress discharge of nitrous oxide gas into the atmosphere.SOLUTION: An inflow nitrogen load control device 21 controls the opening degrees of valves 22a-22d, on the basis of ammonia nitrogen load values in an anoxic tank 12 and aerobic tanks 13a-13c, input from load detection parts 19a-19d, so that an ammonia nitrogen load in each of the tanks becomes less than a predetermined value, and supplies raw water to each of the tanks. Consequently, the ammonia nitrogen load values in the aerobic tanks 13a-13c can be maintained less than the predetermined value to suppress discharge of nitrous oxide gas into the atmosphere. |
