CHEMICAL FATE AND TRANSPORT IN A DOMESTIC SEPTIC SYSTEM - BIODEGRADATION OF LINEAR ALKYLBENZENE SULFONATE (LAS) AND NITRILOTRIACETIC ACID (NTA)

The biodegradation of linear alkylbenzene sulfonate (LAS) and nitrilot riacetic acid (NTA) was assessed in an established septic tank system and an adjoining shallow sand aquifer (located near Cambridge, Ontario ). Studies were conducted on soil, aquifer sediment, and groundwater s amples from a transect of the septic tank effluent plume. LAS and NTA were readily biodegraded in the vicinity of the discharge, with minera lization half-lives in soil and sediment samples collected near the ti le field ranging from 9 to 17 d and 1 to 3 d, respectively. Similar re sults were obtained for ground water. Adaptation was a key process in the system, as illustrated by the rapid biodegradation near the tile f ield and limited biodegradation at locations far downgradient or ungra dient of the system, where little or no LAS or NTA loading occurred. T he results demonstrate that properly functioning septic tank systems c an effectively remove synthetic organic chemicals such as LAS and NTA.