To investigate the impact of graphene oxide (GO) under different concentrations (0, 50, 100, 150, and 200 mg/L) on aerobic granular sludge (AGS) after a single administered dose, the performance of nitrogen removal, microbial enzymatic activity, extracellular polymeric substances (EPSs), and microbial community structure was analyzed in batch tests. The results showed that the impact of GO concentrations on AGS was dose- and time-dependent. Short-term GO exposure could accelerate the nitrification process of AGS, while relatively concentrations (≥100 mg/L) inhibited the process when present for extended periods of time. The microbial enzymatic activity showed similar tendency. The production of lactate dehydrogenase release (LDH) in 200 mg/L group was increased 48.04% and EPS contents decreased 30.06% compared to the control group at 30th day and showed that high concentrations of GO have toxic effects on AGS. The microbial bacteria responded differently to the stimulation of different concentrations of GO. PRACTITIONER POINTS: GO affected AGS system performance in concentration- and time-dependent manners. The nitrification rate of AGS increased in the short term and reversed over time. Long-term exposure to high GO concentrations caused toxicity to AGS. Different microorganisms had diverse responses to GO concentrations.
Keywords: graphene oxide; microbial community; nitrogen removal; toxicity.
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