| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a biological treatment apparatus capable of stably and efficiently remove organic matter with high load and capable of forming sludge good in solid-liquid separability. SOLUTION: A liquid 11 to be treated and return sludge 12 are introduced into a high load biological reaction tank 1 and a mixture of air and a liquid is ejected to a descending pipe 3 from a nozzle 6 to aerate the liquid 11 to be treated and the treatment of the liquid to be treatred is performed with high BOD load in such a state that oxygen dissolving efficiency is kept high to mainly decompose soluble BOD. The mixed liquid of the high load biological reaction tank 1 is introduced into a first flocculation tank 13 to be mixed with activated sludge and aerated from an air diffuser 19 to bond microorganisms to a carrier 23 and the mixed liquid is treated with low BOD load not only to decompose BOD but also to flocculate activated sludge. The mixed liquid in the first flocculation tank 13 is allowed to overflow a partition plate 15 to be allowed to flow in a second flocculation tank 14 to average a stagnation time and treated with low BOD load in the same way as the first flocculation tank not only to decomposed BOD but also to flocculate activated sludge.</p> |
