Performance of Cotton Mat as Pre-Filtration Unit for Groundwater Recharging

Recharging groundwater through rooftop-harvested rainwater has immense potential. In order to manage the instant increase in storm run-off generated from high-intensity rainfall events, a filtration system with high-flow rate is required. Filtration through sand beds is a technique accepted world-wide, but its filtration rate reduces drastically with increase in inflow sediment load. For maintaining the pace in filtration rate through sand bed, a highly efficient, low-cost pre-filtration unit fabricated using cotton mat is recommended. The performances of three- and four-layer cotton mat filters have been evaluated using inflow sediment concentration of 50 and 100 mg/l. Results show that the four-layer cotton mat filter starts delivering sediment-free water much earlier than the three-layer filter, especially at the lower inflow sediment concentration. Moreover, the sediment trapping pattern is influenced by inflow sediment load and the first layer of the cotton mat. Experimental results show that the performance of the cotton mat filter is excellent and can be used as a cost-effective and reliable pre-filtration unit for handling the instant increase in storm runoff during groundwater recharging.