Biological treatment of hexanitrostilbene (HNS) produced wastewater using an anaerobic–aerobic immobilized microbial system

Hexanitrostilbene (HNS) produced wastewater containing complex organic components was subjected to treatment with immobilized bacterial anaerobic–aerobic bioreactor system. After the biological treatment, the chrominance and pungent pyridine odor of the wastewater decreased greatly. The GC–MS analysis of the treated effluent showed that the nitroaromatic compounds like nitrobenzene and dinitrobenzene were almost completely mineralized, and more than 80% of pyridine was removed. Bacterial community analysis revealed that the Pseudomonas group that inhabited the anaerobic filter played a key role in degrading aromatic compounds, while Rhizobiales group found in aerated filter was mainly responsible for the removal of pyridine. This result suggested that bacteria such as Agrobacterium sp., Ensifer adhaerens and Mesorhizobium sp. affiliated with the order Rhizobiales group may be one novel type of pyridine degraders under aerobic condition. The study may be useful for pretreatment of actual explosive production industry wastewater loaded with high concentration toxic organic components.

► A pilot bioreactor system was used to treat actual hazardous wastewater. ► The nitroaromatic compounds could be almost completely mineralized by the system. ► More than 80% of pyridine could be removed by aerobic process of the system. ► The order Rhizobiales group was found to be one novel type of pyridine degrader.