Biological Treatment of 1,4-Dioxane in Wastewater from Landfill by Indigenous Microbes Attached to Flowing Carriers

Abstract

Laboratory and field experiments revealed that indigenous microbes attached to flowing carriers can remove 1,4-dioxane, a recalcitrant substance, from wastewater in landfill facilities. The 1,4-dioxane reduction efficiency of microbes collected from two landfills were different. Landfill Y exhibited higher biodegradation activity than landfill Z. The wastewater of landfill Y contained low biodegradable organic matter as the biochemical oxygen demand (BOD)/chemical oxygen demand (COD) ratio was low, and contained a significantly high proportion of organic carbon in 1,4-dioxane to dissolved organic carbon (> 4.0%). These environmental conditions might have contributed to the high 1,4-dioxane degradation activity of the microbes in landfill Y. Furthermore, the results of the batch experiments suggested that reducing biodegradable organic matter by aeration during pretreatment can accelerate biodegradation. The results also showed that the removal rate constant by stripping and biodegradation for both the batches increased with increasing water temperature. At landfill Y, even at a low temperature of 3°C in the aeration tank that received flowing carriers, over 20% of 1,4-dioxane was removed from wastewater, and a removal rate of 57% was observed at 17°C.