BIOLOGICAL TREATMENT OF 1, 4-DIOXANE IN WASTEWATER FROM AN INTEGRATED POLYETHYLENE TEREPHTHALATE (PET) MANUFACTURING

Polytethylene Terephthalate (PET) manufacturing results in wastewater containing 1,4- dioxane. Regulatory trends indicate that wastewater discharge requirements for 1,4-dioxane will mandate treatment to very low levels. In the past, the options for 1,4-dioxane treatment were considered to be limited to nonbiological energy intensive steam stripping or distillation processes. Bench scale testing of synthetic wastewater demonstrated that 1,4-dioxane is aerobically biodegradable under certain process conditions. Additionally, it was determined that 1,4-dioxane can be removed with advanced oxidation processes (AOP) in combination with biological treatment.Based on this information, eight 1,4-dioxane treatment configurations were pilot tested on 1,4-dioxane wastewater generated from an integrated PET manufacturing facility. The testing evaluated process configurations containing various combinations of upflow anaerobic sludge blanket (UASB), activated sludge, distillation, and AOP technologies. Treatment of 1,4-dioxane to less than 0.04 mg/L was consistently achieved with the UASB/activated sludge and tertiary AOP configurations. The other configurations did not consistently remove 1,4 dioxane below 1 mg/L. UASB pretreatment was used to selectively remove readily biodegradable organic matter from a low-flow, high-concentration stream containing approximately 90 percent of the 1,4-dioxane. Because the 1,4-dioxane was recalcitrant under anaerobic conditions, it passed through the UASB into an aerobic bioreactor which degraded the 1,4-dioxane while also providing a seed culture of 1,4-dioxane degrading microorganisms for an activated sludge system treating the integrated wastewater. This process configuration resulted in removal of 1,4-dioxane to less than 0.04 mg/L.