A review on clogging mechanisms and managements in aquifer storage and recovery (ASR) applications

Clogging, the major obstacle in aquifer storage and recovery (ASR) applications, causes declines in recharge rates and ultimately the failure of artificial recharge systems. Clogging is generally triggered by physical processes, which involve the accumulation of suspended solids from recharge water, the release of fine particles from soils and aquifers and their migration, and the formation of gas barriers from the entrapped air in recharge water and biogenic gases. Physical clogging is then followed by biological processes (e.g., the growth of microorganisms and the accumulation of biomass). It can be further aggravated by chemical reactions leading to mineral precipitation. Prior to artificial recharge, source water can be pretreated via sedimentation, coagulation, filtration, advanced oxidation, and disinfection to lessen the clogging potential. Although such preventive measures are useful, clogging will eventually occur in recharge systems, thus necessitating the rehabilitation. The rehabilitation methods include backwashing, scrubbing, surging, jetting, under-reaming, acidification, and biociding. Notably, the methods applied vary with the type of recharge systems: surface infiltration systems, vadose zone infiltration systems, and aquifer injection wells. Among them, surface infiltration systems are most cost-effective and easiest to install and maintain. Even if field conditions are not adequate for their implementation, surface infiltration systems can be used in conjunction with the other recharge systems.