Stormwater treatment using upflow filters

In this research, an upflow filtration system was developed, and its effectiveness was demonstrated. Five filtration media (lightweight sand, pool-filter sand, fine-grade sand, peat moss and compost were examined for solids removal ability in bench-scale tests. The objectives were to determine (1) the optimum flow rate (no separation of the media from the gravel or within the media, and where suspended solids removal was "best"); (2) the suspended solids loading that reduced the flow rate to certain end points; (3) the breakthrough point (i.e., where the effluent concentration equaled the influent concentration) for each media. The evaluation parameters were flow rate, and effluent turbidity, total solids and particle size distribution. Statistical comparisons of the filters demonstrated that the compost-sand and peat-sand performed better (had greater removals) for turbidity and total solids during the early to the intermediate part of the filter run when compared to sands. Late in the filter run, the peat-sand filter still produced significantly better effluent than the pool sand and the fine sand; however, solids washout from the compost-sand filter occurred and the compost-sand filter performed worse than the two sand filters. For the particle size distribution data, all media were statistically indistinguishable from each other. Copyright ASCE 2005.