Improved methane production from anaerobic wastewater treatment by conductive zero-valent iron@carbon@polyaniline

Abstract

In this study, a core-shell type ZVI@C@PANI nanoparticle was prepared and used as a novel conductive medium for electron transfer between bacteria and archaea of the anaerobic system. The synthesized nanocomposite had favorable biocompatibility and a conductivity of 4.89 S/cm, which made the nanocomposite a good transfer medium to achieve efficient methane production. And the enhanced methane production by adding ZVI@C@PANI in the anaerobic sludge had been investigated. The ZVI@C@PANI enhanced methane yield peaked at doses of 2 g/L. The result showed that methane production increased by 71.36% from the anaerobic system added with the ZVI@C@PANI compared to the control system. Moreover, information on the microorganism community and enzymes in the anaerobic sludge was detected. The results showed that the Geobacter, Syntrophus, and Dechlorobacter bacteria and the Methanosaeta and Methanobacterium archaea were significantly enriched for facilitating direct interspecies electron transfer in the anaerobic system by added ZVI@C@PANI. Moreover, the ZVI@C@PANI can strengthen the production of acetic acid, which facilitated the acetoclastic methanogens to generate methane from the anaerobic system.