单项选择题
A.曝气时间4-8hB.MLSS为4000-6000mg/LC.污泥龄20-40dD.污泥回流比200-300%
A.2-4minB.1-2hC.10-30sD.30-60s
A.16mB.有限制C.不大于100mD.4-7m