Water Science & Technology Vol 65 No 9 pp 1615–1623 © IWA Publishing 2012 doi:10.2166/wst.2012.054

Estimation and modeling of direct rapid sand filtration for total fecal coliform removal from secondary clarifier effluents

Yi Li, Jingjing Yu, Zhigang Liu and Tian Ma

The filtration of fecal coliform from a secondary clarifier effluent was investigated using direct rapid sand filters as tertiary wastewater treatment on a pilot scale. The effect of the flocculation dose, flow loading rate, and grain size on fecal coliform removal was determined. Direct rapid sand filters can remove 0.6–1.5 log-units of fecal coliform, depending on the loading rate and grain size distribution. Meanwhile, the flocculation dose has little effect on coliform removal, and increasing the loading rate and/or grain size decreases the bacteria removal efficiency. A model was then developed for the removal process. Bacteria elimination and inactivation both in the water phase and the sand bed can be described by first-order kinetics. Removal was successfully simulated at different loading rates and grain size distributions and compared with the data obtained using pilot-scale filters.

Keywords: direct rapid sand filters; model; tertiary treatment; wastewater reuse

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