Using Aspergillus niger whole-cell biocatalyst mycelial aerobic granular sludge to treat pharmaceutical wastewater containing β-lactam antibiotics

Abstract

Pharmaceutical wastewater is usually complex and highly toxic, mostly containing antibiotics. The conventional activated sludge technology is unsatisfactory in the treatment of pharmaceutical wastewater owing to the impact of antibiotic toxicity. In this study, a novel whole-cell biocatalyst that can accelerate the degradation of antibiotics was developed by displaying β-lactamase on the cell surface of Aspergillus niger. The biocatalyst showed high enzyme activity (6.53 ± 1.62 U/g dry weight) and stable performance. Cefamezin (80.45%), amoxicillin, and ampicillin were completely degraded by the biocatalyst A. niger-Bla within 1 h owing to the effect of β-lactamase on the β-lactam ring. A. niger mycelial pellets were used as biological carriers to construct aerobic granular sludge (AGS), which was used to treat actual pharmaceutical wastewater containing β-lactam antibiotics. The A. niger-Bla system significantly improves the removal of antibiotics (>60%) and the overall performance of the reactor. The modified A. niger-Bla AGS reduces the impact of antibiotics and maintain the richness and diversity of AGS microbial community, thus improving the system’s overall performance and maintaining the stability of AGS. This technology provides a novel idea to treat pharmaceutical wastewater containing antibiotics.