Molten-salt modified biochar lowered propranolol hydrochloride stress of biomethane production

The pharmaceuticals and personal care products (PPCPs) in wastewater imposed adverse influence on anaerobic digestion (AD). Molten salt-modified biochar (MSBC) was used to lower the interference of some PPCPs like propranolol hydrochloride (PRO) on AD. PRO obviously limited methane (CH 4 ) yields, where 0.3 mM PRO decreased CH 4 yield from 159.52 to 115.50 mL/g-COD, showing a 27.6% decrease. PRO inhibited hydrolysis, acidification and acetogenesis, having strong toxicity to Firmicutes, with its abundance decreasing from 25.8% to 16.1%. The abundance of Methanosaeta in archaea increased, while Methanobacterium reduced, indicating an imbalance in community structure. MSBC effectively lowered PRO inhibition and 800 mg/L of MSBC restored CH 4 yield to 94.3% of the blank group. MSBC increased the relative abundances of electroactive taxa like Chloroflexi , Longilinea , JGI-000079-D21 and Methanosaeta . These changes potentially favored the establishment of a syntrophic metabolic network between Syntrophobacter and Methanosaeta , contributing to interspecies electron transfer, substrate degradation and CH 4 yield.