1,4-DIOXANE BIO-DEGRADATION PILOT STUDY AT THE LOWRY LANDFILL SUPERFUND SITE

Groundwater from the Lowry Landfill Superfund Site just outside of Denver, CO, has been treated using a UV catalyzed hydrogen peroxide advanced oxidation process, which has had difficulty removing a target compound (1,4-dioxane) from some Site groundwater streams to low levels due to UV absorbance/interference issues. Bench-scale studies were completed to investigate biological degradation of the target compound. Seven bench-scale conventional activated sludge systems were operated over six months at a variety of feed mixtures, loading rates, and sludge retention times. The bench scale studies showed that 1,4-dioxane is amenable to biological treatment, with removals to below the detection limit at several operating conditions.Subsequent the bench-scale studies, a Pilot Study was conducted on-site to demonstrate the sustainability of 1,4-dioxane degradation, the consistency of the level of treatment achievable, and to investigate the effects of different operating parameters on the performance of the system. The Pilot Study was operated as a fixed film, moving bed bio-reactor (MBBR) system utilizing Kaldnes® media to support the biological growth. The Pilot Study demonstrated consistent 1,4- dioxane degradation occurred in the presence of tetrahydrafuran (THF) at various operating conditions. Additionally, the study showed that 1,4-dioxane removal efficiency was not significantly affected by temperatures in the 15-25 °C range, at the mass loadings tested.