Performance of composite filter during artificial recharge of ground water

Over exploitation of ground water has occurred in many parts of Punjab because of intensive agriculture and paddy-wheat rotation over the decades with the result that water table has been falling unabatedly in many parts especially the central districts. One way of checking the decline in water table is by artificial recharging of groundwater using surface runoff. In an effort to make the surface runoff silt free before recharge, a horizontal composite filter was developed and tested for its efficacy vis-a-vis changes in water quality and quantity before and after filtration and to estimate the rate of recharge under different conditions. Using this filter, both the filtration efficiency and reduction in turbidity increased from 70 to 77% when 15 cm thickness of sand was combined with coir and gravel of 40 cm thickness each. Reduction in bacterial count increased from 10 to 16% with this filter.