FATE OF CHLORINATION BY-PRODUCTS AND NITROGEN SPECIES DURING EFFLUENTRECHARGE AND SOIL AQUIFER TREATMENT (SAT)

A pilot-scale study was conducted under field conducted under field co nditions to determine the potential role of soil aquifer treatment (SA T) in renovating wastewater effluent to potable water quality. Instrum ented test basins were used to evaluate water quality transformations through the upper vadose zone during effluent recharge. Samples of eit her chlorinated secondary or reclaimed (tertiary) effluent were obtain ed from suction samplers situated in two separate test basins at depth s of up to 6.1 m (20 ft). Samples were characterized according to diss olved organic carbon (DOC), a measurement of dissolved organic matter, and total organic halide (TOX), a measurement of chlorination byprodu cts. Average DOC and TOX removals were 50% and 40%, respectively, for secondary source water; slightly higher removals were observed for ter tiary source water. Performance was found to be affected by operationa l factors; variations in DOC and TOX removal were observed within a we tting cycle as well as from cycle to cycle. Significant nitrification occurred during drying cycles between flooding cycles, resulting in an initial wave of high nitrate in the percolating water.