中试规模的恒速和降速直接过滤系统用于处理高质量地表水，使用两种流速和明矾或阳离子聚合物作为主要混凝剂。浊度、颗粒计数和总大肠菌群计数用于比较滤液质量。两种过滤方案的出水水质基本相同，这一结果与之前使用石灰软化水的研究结果不一致，该研究中，石灰软化水的显著质量优势在于- 测定了废水控制恒速过滤的速率。两种过滤器的水头损失增加率相同，这一结果与之前研究的结论一致。得出的结论是，在未来的研究中，应将四个恒速过滤器（而不是一个）与四个降速过滤器进行比较，以便对滤液质量和运行特性进行更直接和完整的比较。此外，应对每个过滤器系统的单个过滤器以及组合过滤器进行监控。 包括26个参考文献、表格和图表。

Pilot-scale constant-rate and declining-rate direct filtration systems were evaluated for treating a high quality surface water, using two flow rates and alum or cationic polymers as the primary coagulant. Turbidity, particle count, and total coliform count were used to compare filtrate qualities. Effluent quality for the two filtration schemes was essentially identical, a result that disagrees with a previous study using lime-softened water in which a significant quality advantage in declining-rate over effluent-controlled constant rate filtration was determined. The rate of head loss increase was the same for both types of filters, a result which was consistent with conclusions of previous studies. It was concluded that in future studies, four constant rate filters (not one) should be compared with four declining-rate filters to provide a more direct and complete comparison of filtrate quality and operating characteristics. In addition, individual filters as well as combined filters should be monitored for each filter system. Includes 26 references, tables, figures.