Stacked Rapid Sand FiltrationA The stacked rapid sand filtration unit filter is preferable to a conventional rapid sand filtration unit as it requires less water to back wash since the filters are stacked, and use the same water for all filter layers to back washa novel self-backwashing filter invented by the AguaClara team. Its unique stacked geometry allows it to use the same flow rate for the filtration and backwash cycles, without the expensive pumps or elevated tanks required to backwash conventional rapid sand filters. In addition, a stacked filtration system requires a much smaller footprint to achieve the same level of filtrationthan a conventional filter to treat a given flow rate. A vertically stacked filtration system meets many of the AguaClara Project constraints. Both normal filtration and back wash backwash operations are gravity driven and require no electricity. In additon, it is an open system. The required construction materials (PVC pipes, sand, concrete, brick, and rebar) are relatively cheap and available in Honduras. Most importantly, stacked rapid sand filtration is proven to consistently lower the effluent to below 1 the US EPA standard of 0.3 NTU. Field Scale Design We are implementing the first full-scale stacked rapid sand filter as an addition to an existing plant that uses AguaClara technology. It is about to come online in Tamara. Data from this filter will serve as an important field test of the technology and will provide insight to improve future designs. Bench-scale Research We are using bench-scale columns to investigate fundamental questions relevant to stacked filtration technology. For example: is there a difference in particle removal performance between upflow and downflow layers? What range of size and gradation is acceptable in sand media for an SRSF? Pilot-scale Research We are using the SRSF apparatus that has been developed over the past year primarily to test the hydraulics of the siphon control system. We are also collecting data on distribution of flow among the filter layers. Further ReadingLow Flow SRSF Low Flow Stacked Rapid Sand Filters are an adaptation of rapid sand filters optimized for flows less than 3 L/s that don't require any flow control or backwash. Floc Filtration |
Further ReadingProof of Concept Paper
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