Ball-milled Fe0/FeS2 enhanced interaction of Shewanella oneidensis MR-1 with anaerobic microbial community: Impact on 2,4-dichloronitrobenzene reduction and methane yield

The technology of integrating sulfidated zero-valent iron and functional anaerobic bacteria has been extensively explored to improve the removal efficiency of pollutants and enhance the performance of anaerobic microbial system. In this study, the simultaneous DCNB(2,4-dichloronitrobenzene) reduction and methane production by ball-milled 1:1 Fe 0 /FeS 2 (briefly, 1:1 Fe 0 /FeS 2 ), Shewanella oneidensis MR-1 and microbial consortium (MC) were firstly investigated. The result showed that the DCNB reduction was increased by 2.6 and 1.7 times in 1:1 Fe 0 /FeS 2  + MR-1 group compared to 1:1 Fe 0 /FeS 2 and MR-1, respectively, while it further increased by almost 2 times in 1:1 Fe 0 /FeS 2  + MC + MR-1 group as compared to that of 1:1 Fe 0 /FeS 2  + MR-1 group. Moreover, the methane production was drastically facilitated via the reciprocal interaction among FeS as the reaction product, MR-1 and MC. Dechlorination was not found, mainly due to the inability of 1:1 Fe 0 /FeS 2 and the inexistence of dechlorinating bacteria in original inoculum. Meanwhile, the microbial community was also changed, with genera like Eubacterium capable of reducing nitroaromatic compound and Methanosarcina as acetoclastic methanogen enriched by 1:1 Fe 0 /FeS 2 and MR-1. Therefore, fast DCNB reduction and methane production using 1:1 Fe 0 /FeS 2 in anaerobic microbial system, gives useful reference for both establishment of pollutant removal and biogas production. In conclusion, Fe 0 /FeS 2 , as a kind of sulfidated ZVI, is a good candidate for enhancing both pollutant degradation and CH 4 production in anaerobic wastewater treatment.