Enhancing anaerobic methanogenesis in antibiotic pharmaceutical wastewater through graphene particles

Abstract

Anaerobic biological treatment technology offers the capability to efficiently treat antibiotic pharmaceutical wastewater on a large scale with bioenergy recovery potential. However, the inhibitory impact of high concentrations of refractory organic matter on methanogens frequently leads to acidification. This study explored the impact of 0.5 g L−1 graphene particles on the performance, sludge characteristics, community structure, and the enhancement mechanisms in treating chloramphenicol wastewater within an expanded granular sludge bed (EGSB) reactor. Over 80 days, gradient increases in the concentrations of chemical oxygen demand (COD) and chloramphenicol in the influent revealed that graphene particles boosted biogas production by 40.45% and COD removal efficiency by 6.39%. Furthermore, they increased extracellular polymer components (polysaccharides and proteins) by almost twofold and enhanced coenzyme F420 and dehydrogenase activities by 37.89% and 7.34%, respectively. Graphene particles also promoted Methanobacterium and Geobacter abundance, which can participate in direct interspecies electron transfer. The enhancement can be attributed to the surface area and exceptional conductivity, which enrich functional microorganisms and serve as highly efficient electron transfer conduits, expediting electron transfer rates. These findings suggest graphene particles have significant potential in bioremediation, especially for anaerobic methanogenesis from refractory wastewater.