摘要 |
A fully mixed reactor (1) for activated sludge treatment of sewage as a mixed liquor which reactor (1) includes at least one aerator (6) operative intermittently to raise the dissolved oxygen level of the liquor and a control system (7) which is arranged to operate the aerator (6) to provide an operative phase including a predetermined aerobic time period after a first dissolved oxygen target level is reached, and an inoperative phase including a predetermined anoxic time period after a second, lower, dissolved oxygen target level is reached, is provided. <IMAGE> |