Anaerobic Treatment of Industrial Wastewater Containing N, N-Dimethylformamide (DMF) with Anaerobic Membrane Bioreactor (AnMBR): Long-term Operation and Microbial Community

摘要

Wastewater containing approximately 2000 mg L~(-1) N, N-dimethylformarnide (DMF) was treated by a lab-scale anaerobic membrane bioreactor (AnMBR). The complete methanogenic degradation of DMF was achieved by an artificially co-cultured inoculum being consisted of aerobic DMF-hydrolyzing activated sludge and normal anaerobic digested sludge. The results of a 250-day long-term operation demonstrated that under a low organic loading rate (OLR) of 3.14 ～ 4.16 g COD L~(-1) d~(-1) , the AnMBR maintained excellent DMF removal efficiency and high methane production. However, the elevation of OLR significantly limited DMF hydrolysis. When OLR exceeded 6.54 g COD L~(-1) d~(-1), both DMF removal efficiency and methane production dramatically dropped. The high CH4 content in the biogas, exceeding 85%, was shown to be the reason for the suitability of anaerobic treatment to DMF. The inoculum contains abundant DMF-hydrolyzing bacteria such as Paracoccus, Hyphomicrobium, Burkholderia, Catellibacterium, Bacillus and Bradyrhizobium which have potential to hydrolyze DMF into intermediates. DMF-hydrolyzing bacteria gradually decayed under the anaerobic condition, resulting in the weak hydrolysis of DMF. Due to the lack of nitrate, these denitrifying bacteria kept decaying rather than proliferating. Dosage of nitrate is considered to help to enrich the DMF-hydrolyzing bacteria in order to establish a stable DMF-degrading consortium.