Fate of organics in sewage effluent during soil aquifer treatment in soil columns

Abstract

Unsaturated soil column experiments were performed to 1) differentiate biological and abiotic mechanisms for removal of dissolved organics in chlorinated municipal effluent and 2) determine efficacy of additional effluent pre-treatments (tertiary filtration and ozonation) during soil aquifer treatment (SAT). Three water quality parameters were examined: dissolved organic carbon (DOC), UV absorbance at 254 nanometers (UV A254), and adsorbable organic halide (AOX). DOC was removed primarily by biological activity during SAT. The average through-column removal using chlorinated secondary effluent was 48 %. UVA254 removals were dependent on both biological and abiotic mechanisms. AOX was removed primarily by sorption. Average removals for UV A254 and AOX were 30 and 17 %, respectively. Forty-four percent of the through column DOC removal and 57 % ofUVA254 attenuation occurred in the top 8 cm of soil. Tertiary filtration and pre-ozonation provided no significant additional water organic quality benefits following SAT.