Field Test of On-Site Treatment of 1,4-Dioxane-Contaminated Groundwater Using Pseudonocardiasp. D17

Abstract

Contamination of groundwater by 1,4-dioxane has been detected in many regions worldwide, especially in illegal industrial waste dumping sites. As 1,4-dioxane is a potential human carcinogen that is highly resistant to most conventional biological and physicochemical treatments, the development of a practical application method for treating 1,4-dioxane-contaminated groundwater is strongly desirable. Therefore, this study aimed to develop an on-site treatment system for 1,4-dioxane-contaminated groundwater using Pseudonocardiasp. D17, and assess the feasibility of the developed system for long-term treatment. This bacterial strain is capable of constitutively degrading 1,4-dioxane and using it as a source of carbon and energy. The on-site treatment of 1,4-dioxane-contaminated groundwater was performed in a 450-L continuous-flow bioreactor using strain D17 with a hydraulic retention time of 12 - 18 h. To maintain a sufficiently high microbial concentration, strain D17 was monitored by qPCR, targeting the thmCgene associated with 1,4-dioxane degradation, and inoculated when needed. 1,4-Dioxane removal to meet the Japanese environmental quality standard for groundwater pollution (0.05 mg/L) was achieved for nearly 3 months by the additional inoculation of strain D17. These results suggest that on-site treatment using strain D17 could provide a practical solution for the treatment of 1,4-dioxane-contaminated groundwater.