Clarification of Surface Waters for Recharge through Wells

摘要

Clogging of the well face is a major impediment to artificial recharge of confined aquifers through wells. It appears that continuous recharge requires particle-free water. The use of surface waters for such recharge, therefore, requires treatment to remove suspended material. This report describes an investigation of a novel aggregation and sedimentation process that promised to provide low cost removal of particles. Extensive testing to evaluate velocity gradients and overflow rates, using suspensions of montmorillonite and kaolinite clays, showed that changing velocity gradients over the range of 4 to 16/sec had a small effect with the optimum near 8/sec. Increasing the overflow rate above .036 cm/sec reduced the effectiveness of the sedimentation stage. The aggregation and sedimentation process does not produce an effluent that is suitable for recharge through wells. A fine sand pressure filter would be required to polish the effluent before injection.