A wedge-shape column study on colloidal transport and retention in aquifer storage and recharge

Abstract

Aquifer Storage and Recharge (ASR) is an effective technology for replenishing depleted groundwater and balancing the seasonal differences of rainfalls. Recent years have seen a growing interest in injecting highly treated wastewater into the aquifer in order to augment fresh water resources and to use the natural attenuation mechanism to further improve the quality of recycled water. However, injecting reclaimed wastewater into the groundwater system not only raises uncertainties upon the potential impact on the subformation eco-system and drinking water safety, but also presents new operational challenges for the hydrologists. Well clogging often occurs in both injection and pumping wells, mostly due to the mobilization of the fine particles, which clog the pore throats. The propensity of clogging primarily depends on the chemical and physical constitution of the permeable subformation and the water quality of the injecting water. This study presents a new design of a wedge-shape column for investigate the fines transport and retention problem with a close remembrance to field scenario. A series of results were obtained from the wedge-shape column study on the evolving formation permeability and fines transport and retention as a result of changing water quality. The results suggest that it may not be operational sustainable to directly inject highly treated wastewater (particularly RO treated) into the aquifer formation.