Insights into synergistic metabolism of phenol and ammonium pollutants in treating coal gasification wastewater by algal-microbial fuel cell

The coexistence of phenol and ammonium induced mutual antagonism largely and hindered the application of biological treatment in coal gasification wastewater (CGW). A novel algal-microbial fuel cell (AMFC) was employed to separate and cleanse phenol and ammonium pollutants, and the insights into biological process were explored. Two types of AMFCs were developed to simultaneously remove phenol and ammonium from CGW, with cyanobacteria and green algal as the cathodes, respectively. The AMFC with Synechocystis cathode exhibited superior performance, removing COD and NH4+-N of 94.82 % and 20.16 %, about 1.12 and 1.06 times higher than the AFMC with Chlorella cathode. Meanwhile, the maximum power density of the AMFC with Synechocystis cathode was enhanced by 40.34 %. The conductive Synechocystis on the cathode and generated biomass on the anode might cooperate to facilitate extracellular electron transfer (EET), which consequently accelerated the separation and cooperative removal of phenol and ammonium in AMFC. By microbial community analysis, the microbiota in biofilm and generated biomass was respective keystone contributor to phenolic degradation and biomass transformation. Meanwhile, Chryseobacterium was the leading bacteria and might dominate both phenol degrading and the generated biomass formation.

Automated summary

In this study, a novel algal-microbial fuel cell (AMFC) was used to successfully separate and cleanse phenol and ammonium pollutants in coal gasification wastewater (CGW), and the biological process was explored. The AMFC with Synechocystis cathode showed superior performance, removing COD and NH4+-N more efficiently and achieving a higher maximum power density. Microbial community analysis revealed the key microorganisms in the biofilm and generated biomass, which played important roles in phenol degradation and biomass transformation.