In this work, the perovskite LaZnO₃ was synthesized via sol-gel method and applied for photocatalytic treatment of sulfamethizole (SMZ) antibiotics under visible light activation. SMZ was almost completely degraded (99.2% ± 0.3%) within 4 hr by photocatalyst LaZnO₃ at the optimal dosage of 1.1 g/L, with a mineralization proportion of 58.7% ± 0.4%. The efficient performance of LaZnO₃ can be attributed to its wide-range light absorption and the appropriate energy band edge levels, which facilitate the formation of active agents such as ·O₂^-, h⁺, and ·OH. The integration of RP-HPLC/Q-TOF-MS and DFT-based computational techniques revealed three degradation pathways of SMZ, which were initiated by the deamination reaction at the aniline ring, the breakdown of the sulfonamide moieties, and a process known as Smile-type rearrangement and SO₂ intrusion. Corresponding toxicity of SMZ and the intermediates were analyzed by quantitative structure activity relationship (QSAR), indicating the effectiveness of LaZnO₃-based photocatalysis in preventing secondary pollution of the intermediates to the ecosystem during the degradation process. The visible-light-activated photocatalyst LaZnO₃ exhibited efficient performance in the occurrence of inorganic anions and maintained high durability across multiple recycling tests, making it a promising candidate for practical antibiotic treatment.

2023-11-01·Journal of Environmental Management

Occurrence and prevalence of antibiotics in wastewater treatment plants and effluent receiving rivers in South Africa using UHPLC-MS determination

Article

作者: Maseko, Bethusile Rejoice ; Olowoyo, Oluwole Joshua ; Madikizela, Mzukisi Lawrence ; Ncube, Somandla ; Nyoni, Hlengilizwe ; Oharisi, Omuferen-Oke Loveth

The increased usage of antibiotics over the recent years has led to an increased interest in monitoring their presence in wastewater all over the world. In this study the occurrence of sixteen (16) selected antibiotics (amoxicillin, ampicillin, azithromycin, ciprofloxacin, doxycycline, erythromycin, gentamicin, metronidazole, norfloxacin, ofloxacin, penicillin, sulfamethoxazole, sulfapyridine, sulfamethizole, tetracycline and trimethoprim) were determined in two wastewater treatment plants and two effluent receiving rivers in Northern part of Pretoria, South Africa. Targeted screening and identification of antibiotics was done using ultra high-performance liquid chromatography coupled with mass spectrometry after sample clean-up and pre-concentration using solid phase extraction. The concentrations of the targeted antibiotics detected in influent samples ranged between 0.78 and 96.8 ng mL^-1 and those in effluent were between 0.12 and 9.89 ng mL^-1. The highest recorded concentrations in all samples were those of doxycycline (30.9-120 ng mL^-1) and sulfamethoxazole (2.52-96.8 ng mL^-1) in effluent and influent samples, respectively. The concentrations of antibiotics in the rivers receiving effluents were between 0.03 and 72.8 ng mL^-1 in upstream samples and 0.008-76.8 ng mL^-1 in downstream samples, indicating that there is other source of contaminate to these rivers other than the treatment plants. Risk assessment using the hazard quotients ranged between 0.24 and 889 indicating that the presence of these antibiotics and antibiotic mixtures posed higher ecological risks to aquatic organisms. From the study, it could be concluded that wastewater treatment plants were releasing antibiotics to the environment and posing a risk to the aquatic ecosystem and public health. Therefore, there is a need to research into developing more efficient conventional wastewater treatment technologies that can completely remove antibiotics from wastewater.

2023-07-06·Membranes

Effects of High Pharmaceutical Concentrations in Domestic Wastewater on Membrane Bioreactor Treatment Systems: Performance and Microbial Community.

Article

作者: Du, Xin ; Zhang, Zhenghua ; Li, Chengyue ; Huang, Chuyi

Despite pharmaceuticals being widely detected in water-bodies worldwide, what remain unclear are the effects of high pharmaceutical concentrations on the treatment efficiency of biological wastewater treatment processes, such as membrane bioreactor (MBR) systems. This study investigated the efficiency of MBR technology in the treatment of synthetic wastewater containing a mixture of five typical pharmaceuticals (ofloxacin, sulfamethoxazole, sulfamethylthiadiazole, carbamazepine and naproxen) with a total concentration of 500 µg/L. Both the control MBR (MBRc) without pharmaceutical dosing and the MBR operated with high influent pharmaceutical concentrations (MBRe) were operated under room temperature with the same hydraulic retention time of 11 h and the same sludge retention time of 30 d. The removal efficiency rates of total nitrogen and total phosphorus were 83.2% vs. 90.1% and 72.6% vs. 57.8% in the MBRc vs. MBRe systems, and both MBRs achieved >98% removal of organics for a 180-day period. The floc size decreased, and membrane fouling became more severe in the MBRe system. Microbial diversity increased in the MBRe system and the relative abundances of functional microbe differed between the two MBRs. Furthermore, the total relative abundances of genes involved in glycolysis, assimilating nitrate reduction and nitrification processes increased in the MBRe system, which could account for the higher organics and nitrogen removal performance. This work provides insights for MBR operation in wastewater treatment with high pharmaceutical concentrations.

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