Experimental study on clogging and water quality change during artificial recharge

In this paper, an experimental sand column was used to investigate the clogging process and water quality changes simultaneously during artificial recharge. Clogging was described quantitatively according to the changes of hydraulic conductivity, whilst several important water quality parameters, such as SS, total bacterial count, DO, TOC, total nitrogen, total phosphorus were measured at regular time intervals during recharge. After 80 hours of continuous recharge, the hydraulic conductivity of the upper column (10-15cm) and the lower(15-55cm) decreased from 1.23x10(-4)m/s to 9.84x10(-5)m/s and from 1.23x10(-4)m/s to 1.06x10(-4)m/s, respectively. This was thought to be due to physical clogging by suspended solids and then biological clogging by biomass accumulation along the columns. The sand column had significant self-purification effect on suspended matter, bacteria, TOC, permanganate index, total nitrogen, total phosphorus, copper, etc. The filtration and adsorption effect of the upper column were much stronger than that of the lower, so the clogging of the upper was more severe. The results of this study will provide technical support for the implementation of large-scale artificial recharge in the Liaolan groundwater funnel area of Qingdao.