1,4 dioxane removal from groundwater using point-of-entry water treatment techniques

This feasibility study investigated the removal of an emerging organic contaminant, 1,4 dioxane, from groundwater using point-of-entry (POE) treatment techniques in response to its discovery in some small New Hampshire groundwater-based private drinking water systems. The New Hampshire Department of Environmental Services (NHDES) is evaluating future treatment options for dioxane contamination of these small, groundwater-based private systems. Treatment technologies assessed for dioxane removal included: air stripping, carbon adsorption, direct UV photolysis, and UV-peroxide (H2O2) oxidation. Criteria used to assess the suitability of these technologies for POE application included: dioxane removal efficiency, capital and operations and maintenance (O & M) cost, ease of use, and safety. Initial tests indicated that air stripping and direct photolysis were not feasible treatment options for a maximum contaminant level (MCL) of 3 mug/L dioxane. Carbon adsorption and UV-Peroxide oxidation were both found to treat dioxane to ≤ 3 mug/L (96% and 82% removal, respectively). This study determined that carbon adsorption using a coconut-based carbon is the most feasible dioxane treatment option for a POE system based on cost evaluations and treatment experience.