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The model incorporates catchment and rainfall characteristics including the effective impervious area, time of concentration, rain duration, average rainfall intensity and the antecedent dry period as the contributors to random effects.1,4-Dioxane is one of the most persistent organic micropollutants in conventional drinking-water-treatment processes. Vacuum ultraviolet (VUV) treatment is a promising means of removing micropollutants such as 1,4-dioxane from source water, but this approach has not yet been implemented in a full-scale water treatment plant, partly because the operating parameters for pilot and full-scale VUV photoreactors have not been optimized. Here, we developed a computational fluid dynamics-based method for optimizing VUV photoreactor performance through energy-based analyses that take into account the effects of two important operating parameters-flow rate and radiant exitance. First, we constructed a computational fluid dynamics model and determined the sole parameter required for the model, the pseudo-first-order rate constant for the reaction of 1,4-dioxane, by simple batch experiment. Then, we validated the model by using a pilot-scale flow-through annular photoreactor. Finally, we used the validated model to examine the effects of flow rate and radiant exitance on the efficiency of 1,4-dioxane degradation in a virtual annular photoreactor. Radiation efficiency, which was defined as the ratio of the logarithmic residual ratio of 1,4-dioxane to the theoretical minimum logarithmic residual ratio (best possible performance) under the given operating conditions, was calculated as an energy-based index of cost-effectiveness. Radiation efficiency was found to increase with increasing flow rate but decreasing radiant exitance. An electrical energy per order (EEO) analysis suggested that VUV treatment under laminar flow was most economical when low-power lamps and a high flow rate were used. In contrast, VUV treatment under turbulent flow was suggested to be most economical when high-power lamps were used at a high flow rate.Although photo-driven advanced oxidation processes (AOPs) have been developed to treat wastewater, few studies have investigated the feasibility of AOPs to simultaneously remove antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs) and micropollutants (MPs). This study employed a modified photo-Fenton process using ethylenediamine-N,N'-disuccinic acid (EDDS) to chelate iron(III), thus maintaining the reaction pH in a neutral range. Simultaneous removal of ARB and associated extracellular (e-ARGs) and intracellular ARGs (i-ARGs), was assessed by bacterial cell culture, qPCR and atomic force microscopy. The removal of five MPs was also evaluated by liquid chromatography coupled with mass spectrometry. A low dose comprising 0.1 mM Fe(III), 0.2 mM EDDS, and 0.3 mM hydrogen peroxide (H2O2) was found to be effective for decreasing ARB by 6-log within 30 min, and e-ARGs by 6-log within 10 min. No ARB regrowth occurred after 48-h, suggesting that the proposed process is an effective disinfectant against ARB. Moreover, five recalcitrant MPs (carbamazepine, diclofenac, sulfamethoxazole, mecoprop and benzotriazole at an initial concentration of 10 μg/L each) were >99% removed after 30 min treatment in ultrapure water. The modified photo-Fenton process was also validated using synthetic wastewater and real secondary wastewater effluent as matrices, and results suggest the dosage should be doubled to ensure equivalent removal performance. Collectively, this study demonstrated that the modified process is an optimistic 'one-stop' solution to simultaneously mitigate both chemical and biological hazards.The impact of HCO3- on the photodegradation of β-blockers was investigated under simulated sunlight irradiation. The results show that in the presence of HCO3-, the photodegradation rates increase significantly for sotalol (SOT), whereas no effects on the degradation of carvedilol and arotinolol are observed. Using quenching experiments, electron paramagnetic resonance spectra and degradation product determination, we demonstrate that carbonate radical (CO3•-) is formed by direct oxidation of HCO3- by triplet-excited SOT (3SOT*) and plays a significant role in SOT photodegradation. Competition kinetics experiments show that the three β-blockers all have high second-order rate constants (107-108 M-1 s-1) for the reaction with CO3•-. However, only 3SOT* has a higher reduction potential that can oxidize HCO3- to produce CO3•-. Thus, enhanced SOT removal rates in the presence of HCO3- were observed. In addition, the results show that seawater DOM could increase HCO3--induced photodegradation of SOT, whereas SRNOM mainly behaves as a CO3•- quencher and decreases the removal rate of SOT. The results underscore the role of HCO3- in limiting the persistence of organic pollutants like SOT in sunlit natural waters, and especially in marine and coastal waters.While the ubiquitous presence of comammox in engineered systems provides the foundation of developing a novel biological nitrogen removal process, factors contributing to the comammox dynamics in engineered systems have not been well resolved. Here, we investigate the long-term effects of ten different antibiotics on microbial community dynamics in activated sludge and the results show that both types and concentrations of antibiotics affect the taxonomic composition of nitrifiers, including comammox, ammonia-oxidizing bacteria, and canonical nitrite-oxidizing bacteria. Specifically, phylogenetically different comammox Nitrospira were selectively enriched by four types of antibiotics (i.e., ampicillin, kanamycin, lincomycin, and trimethoprim). ASN-002 inhibitor Comparative genomic analysis of the four newly identified comammox clade A Nitrospira revealed that the comammox enriched by antibiotics shared the conserved key metabolic potentials, such as carbon fixation, complete ammonia oxidation, and utilization of hydrogen as alternative electron donors, among the known comammox organisms. Comammox strains enriched in this study also encoded genes involved in formate and cyanate metabolism that were recently reported in comammox clade A organisms from wastewater treatment systems. Our findings highlight that the comammox in activated sludge ecosystems possess high metabolic versatility than previously recognized and could be selectively enriched by some antibiotics.
Here's my website: https://www.selleckchem.com/products/gusacitinib.html
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