Long-term effect of graphene oxide on the aerobic granular sludge wastewater treatment process

This study investigated the bioreactor performance, production of extracellular polymeric substance (EPS), and microbial activity a granulated sequencing batch reactor (SBR) by increasing graphene oxide nanoparticle (GO NP) concentration stepwise. The GO NPs reduced removal chemical oxygen demand (COD), ammonia, phosphorus, whereas nitrite nitrate contents effluent were kept stable during experiment. ammonia-nitrogen (NH4-N) COD rates deceased considerably from 99% 95–96.2% 78.6% at 55 mg/L NPs; furthermore, 115 NPs, NH4-N further decreased to 88.5% 59.3%. phosphorus even small concentrations (GO), inhibitory effect enhanced with an increase in NP content. increased amounts nanoparticles significantly influenced aerobic granular sludge (AGS). specific uptake rate (SOUR) 42.04 33.14 mg O2/g MLVSS*h, ammonia oxidation (SAOR) declined 4.84 4.12 N/g (SPUR), release (SPRR) 13.1 10.05–8.2 8.7 P/g MLVSS*h after 98 days. However, reduction (SNIRR SNRR), (SNOR) remained relatively stable. EPS content was initially 5.95 mg/g MLVSS, but presence up promoted secretion 11.86 MLVSS. At higher concentrations, inhibited. After 14 days, when influent synthetic wastewater (SWW) did not contain NP, AGS SBR performance showed remarkable recovery capability.