Removal Efficiency Of Emerging Contaminants In Water On Ore/Biochar-Amended Bioretention

In recent years,antibiotics and nanoplastics,known as typical emerging contaminants,have been frequently detected in surface water,soil environment,and wastewater treatment plants.They pose serious threats to the ecosystem and human health.Bioretention is an important facility used in sponge city and has gradually attracted attention due to the advantages of wide application low cost,easy operation,and maintenance.Optimizing the conventional bioretention to enhance its performance under the stress of antibiotics and nanoplastics is crucial for better-applying bioretention for wastewater treatment.Four bioretention systems planted with Acorus tatarinowii were constructed to better understand the effects of structural modification on system performance.The performance of systems was comprehensively explored under the stress of sulfamethoxazole（SMX）and tetracycline（TC）（0.2 mg/L+0.2 mg/L and 0.4 mg/L+0.4 mg/L）,to obtain the best modification of bioretention systems.In addition,the shifts of the microbial community by high-throughput sequencing and the abundance of denitrification genes（nir K,nir S and nos Z）by quantitative PCR（q PCR）were also examined to reveal the mechanisms associated with pollutants removal.Moreover,the fates of SMX/TC and corresponding ARGs（sul I,sul II,tet A and tet C）were investigated.According to the findings of the above study,five bioretention systems planted with Iris pseudacorus were constructed.The performance of these BRSs under the stress of0.5 mg/L polymethyl methacrylate（PMMA）nanoplastics was investigated to obtain the best structure of the bioretention systems.In addition,the shifts of substrates enzymatic activities（urease（URE）,ammonia monohydrogenase（AMO）,and nitrite reductase（NIR））,the microbial community,and the abundance of denitrification genes（nir K,nir S and nos Z）were examined to comprehensively reveal the mechanisms of pollutants removal.Furthermore,the changes of catalase（CAT）activities and malondialdehyde（MDA）contents in the leaves of Iris pseudacorus were explored.The leaching of heavy metals in ore-amended BRSs was investigated to evaluate the application prospect of amendment bioretention.The results showed that the removals of SMX and TC in BC-BRC,EBC-BRC,and Fe/BC-BRC were all greater than 99.9%,which was much higher than that with BRC（30.86-63.03%）.Fe/BC-BRC outcompeted those systems in removing nutrients under the stress of antibiotics（COD:89.74%,NH₄⁺-N:89.15%,TN:89.15%,and TP:98.27%）.The abundance of key microorganisms in the substrates of BRCs was affected and the abundance of nir K,nir S and nos Z gradually decreased along with antibiotics exposure.Moreover,the lower layers of Fe/BC-BRC contained significantly enriched Ferritrophicum,Desulfomicrobium and Desulfuromonas,which benefited nitrogen removal and antibiotic degradation.The abundance of ARGs in all BRCs increased along with antibiotics exposure,and microorganisms encoding ARGs gradually became the dominant bacteria.Fe/BC-BRC led to one order of magnitude less ARGs in the effluent.The exposure of PMMA nanoparticles adversely affected the system performance on nitrogen and phosphorus removals,but the amendment with ore significantly mitigated the stress of PMMA.The removal efficiencies of nutrients in BRS-MFC-BC-Mn O₂（COD:86.96%,NH₄⁺-N:92.57%,TN:80.76%,and TP:96.69%）and BRS-MFC-BC-Fe S₂（COD:90.34%,NH₄⁺-N:98.67%,TN:72.91%,and TP:92.74%）were better than others.The substrates enzymatic activities（URE,AMO and NIR）decreased gradually and the abundance of key microorganisms and denitrification genes（nir K,nir S and nos Z）altered under the stress of PMMA.Thiobacillus,Geobacter,Anaeromyxobacter,Gallionella,Desulfomicrobium and Desulfobulbus responsible for COD,nitrogen and phosphorus removals were all enriched in the lower layers of BRS-MFC-BC-Mn O₂,BRS-BC-Fe S₂ and BRS-MFC-BC-Fe S₂.Besides,the addition of PMMA decreased the CAT activities and increased the contents of MDA of Iris pseudacorus in BRSs,thus destroying the oxidative balance in plants.The leaching concentration of heavy metals in BRSs could meet the standard of heavy metal discharge.In general,Fe/BC-BRC,BRS-MFC-BC-Mn O₂ and BRS-MFC-BC-Fe S₂ showed more excellent performance in mitigating the adverse effects of emerging contaminants and achieving highly efficient nitrogen and phosphorus removals.This study provided scientific insights and technical support for the enhancement of bioretention.