Research On The Mechanism Of Nanoparticles And Antibiotics During Sludge Anaerobic Digestion

In recent years,with the development of social economy,people were using nanoparticles and antibiotics increasingly to meet the needs of production and life,while a large amount of wastewater containing nanoparticles and antibiotics was gathered together with municipal drainage networks to wastewater treatment plants?WWTPs?.The activated sludge process is commonly used in WWTPs.Nanoparticles and antibiotics accumulated on the surface of activated sludge and were discharged with excess sludge which will cause environmental risks.Sludge anaerobic digestion is a common sludge treatment method.When nanoparticles and antibiotics coexist in the sludge,the complex mechanism between them is still to be studied.In this study,based on the actual contamination levels of nanoparticles and antibiotics reported in the literature,individual pollutant experiment was conducted to determine the pollutant composition and its concentration in the complex pollution experiment.The interaction between ZnO nanoparticle and carbon nanoparticles or antibiotics,ZnO nanoparticle and different antibiotics were compared,in the complex pollution experiment.This study analyzes from metabolic levels?carbohydrate,protein,volatile fatty acids?,microbial community levels?bacteria,archaea?and the interaction between pollutants?metal dissolution,complexation equilibrium?in sludge anaerobic digestion to conclude the complex mechanism of metal oxide nanoparticle and antibiotic during sludge anaerobic digestion.The study found that the complex of nano-ZnO and antibiotics showed toxicity synergistic effect and of nano-ZnO+ciprofloxacin was the most obvious while the addition of norfloxacin and sulfamethazine were weaker,C₆₀ showed no effect.In the short term,the complex pollutants mainly inhibited the degradation of protein and carbohydrates,especially the inhibition of carbohydrates by nano-ZnO+ciprofloxacin was 78.1%,thereby reducing the content of volatile fatty acids.The presence of antibiotics promote the release of Zn²⁺from nano-ZnO.Through high-throughput sequencing found that for bacterial communities,complex pollutants mainly affect hydrolysis and acidification bacteria,while in archaeal communities mainly inhibit methanogens metabolism.