在生物双介质（无烟煤砂）过滤器中，用非氯化水反洗不会影响附着在过滤器顶部介质上的生物量，也不会影响总有机碳、消毒副产物（DBP）前体或臭氧DBP的控制。然而，用氯化水反洗一个类似的过滤器，会导致附着在过滤器顶部介质上的生物量浓度降低，并降低相同参数的稳态去除率。在用氯化水反洗后，过滤器顶部的一些附着生物量立即损失，但在过滤器循环的后期，生物量恢复到反洗前的浓度。与生物量损失同时出现的是过滤废水中臭氧DBP浓度的增加； 在过滤器循环的后期，这些浓度也恢复到反冲洗前的浓度。包括16个参考文献、表格、图表。

In a biological dual-media (anthracite-sand) filter, backwashing with nonchlorinated water did not affect the biomass attached to the media at the top of the filter or the control of total organic carbon, disinfection byproduct (DBP) precursors, or ozone DBPs. Backwashing a similar filter with chlorinated water, however, resulted in lower concentrations of biomass attached to the media at the top of the filter and lower steady-state removal of the same parameters. A loss of some of the attached biomass at the top of the filter occurred immediately after backwashing with chlorinated water, but later in the filter cycle the biomass recovered to its prebackwashing concentration. Concurrent with this loss of biomass was an increase in the concentrations of ozone DBPs in the filter effluent; these also recovered to prebackwashing concentrations later in the filter cycle. Includes 16 references, table, figures.