找考题网-背景图
单项选择题

砂滤出水菌落总数较进水菌落总数明显增加的处理措施为()

A.50-150ppm余氯浸泡30min
B.25-50ppm余氯浸泡60min
C.25-50ppm余氯浸泡30min
D.50-100ppm余氯浸泡30min