Regulating the porous properties of polyaniline enhances the electron transfer process and methane production during anaerobic wastewater treatment

Conductive materials are known to enhance methane production in anaerobic treatment process by facilitating direct interspecies electron transfer (DIET). However, the role of the porous structure of conductive materials in electron transfer remains underexplored. Polyaniline (PANI) was used as conductive materials in this study due to its easily controlled porosity, investigating how surface area and pore size affect methane production. It was demonstrated that the porosity of PANI is an important factor affecting methane production by anaerobic sludge. Methane production rate of 41.2 mL/h was achieved with the high-porosity PANI, which was ~73.2% higher than the control group. The porous PANI enhanced the electric field in the anaerobic sludge, facilitating the enrichment of electrogenic bacteria and archaea. In the anaerobic system supplemented with porous PANI, the maximum accumulation of acetic acid reached 3.72 mM. The abundance of electroactive bacteria Clostridium involved in DIET increased by 2.13-fold, while the abundance of electroactive archaea Methanosaeta and Methanobacterium, which also participate in DIET, rose by 1.55-fold. The porous structure of PANI promotes DIET and enhances aceticlastic methanogenesis.