Effect of soil type on water quality improvement during soil aquifer treatment

Abstract

inch-scale soil column experiments were performed at The University of Arizona to examine the effects soil type and infiltration rate on the removal of wastewater organcs during soil aquifer treatment ~AT). The suitability of such waters for potable uses following a combination of above-ground treatments id SAT polishing was under investigation. SAT was simulated in 1-meter soil columns containing packed homogenized soils ranging from poorly graded sands to silty sands. Soils were obtained from ,isting and potential effluent recharge sites in Arizona. All columns received chlorinated/dechlorinated condary effluent, ponded to a 25-cm depth above the soil surface, under alternating wet/dry conditions. reatment efficiencies in biologically active and inhibited columns were compared to determine the echanism(s) of water quality improvements and the sustainability of SAT. Water quality parameters eluded: (i) non-purgable dissolved organic carbon and (ii) UV absorbance at 254 nm (used as a measure disinfection-by-product precursors). Differences in through-column removal of non-purgable dissolved ,.ganic carbon were significant for columns containing sandy loam (56%), sand (48%) and silty sand 4%). Removal of UV-absorbing organcs was not significantly different for columns containing sand and [ndy loam (22 and 20%, respectively). There was no significant correlation between infiltration rate and moval efficiency of either organic parameter for both soils.