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1.
Norfloxacin-induced effect on enhanced biological phosphorus removal from wastewater after long-term exposure.
Xu, Q, Liu, X, Yang, G, Wang, D, Wu, Y, Li, Y, Huang, X, Fu, Q, Wang, Q, Liu, Y, et al
Journal of hazardous materials. 2020;:122336
Abstract
In this study, long-term experiments were performed under synthetic wastewater conditions to evaluated the potential impacts of norfloxacin (NOR) (10, 100 and 500 μg/L) on enhanced biological phosphorus removal (EBPR). Experimental result showed that long-term exposure to 10 μg/L NOR induced negligible effects on phosphorus removal. The presence of 100 μg/L NOR slightly decreased phosphorus removal efficiency to 94.41 ± 1.59 %. However, when NOR level further increased to 500 μg/L, phosphorus removal efficiency was significantly decreased from 97.96 ± 0.8 5% (control) to 82.33 ± 3.07 %. The mechanism study revealed that the presence of 500 μg/L NOR inhibited anaerobic phosphorus release and acetate uptake as well as aerobic phosphorus uptake during long-term exposure. It was also found that 500 μg/L NOR exposure suppressed the activity of key enzymes related to phosphorus removal but promoted the transformations of intracellular polyhydroxyalkanoate and glycogen. Microbial analysis revealed that that the presence of 500 μg/L NOR reduced the abundances of polyphosphate accumulating organisms but increased glycogen accumulating organisms, as compared the control.
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2.
Comparative study of Cu-based bimetallic oxides for Fenton-like degradation of organic pollutants.
Wang, Q, Ma, Y, Xing, S
Chemosphere. 2018;:450-456
Abstract
In order to provide useful information for the rational design of effective Fenton-like catalyst, a series of Cu-based bimetallic oxides were synthesized and their Fenton-like performances for the degradation of Orange II and ciprofloxacin were compared. The structure, chemical oxidation state, surface charge property and redox ability of the catalysts were also investigated by different characterization techniques. Among them, NiCu exhibited the highest adsorption capacity towards Orange II and the highest activity for the production of OH from H2O2 decomposition, which could be attributed to its high surface area and highly positively charged surface. However, FeCu exhibited the highest activity for the degradation of Orange II. The reason might be that FeCu has more unpaired electrons and higher redox ability, thus promoting the activation of adsorbed Orange II through the electron transfer process. By contrast, NiCu exhibited the highest activity for the removal of ciprofloxacin because ciprofloxacin was mainly degraded by OH. Finally, the main degradation intermediates of Orange II and ciprofloxacin were determined by liquid chromatography-mass spectrometry.
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3.
Plant uptake of diclofenac in a mesocosm-scale free water surface constructed wetland by Cyperus alternifolius.
Zhai, J, Rahaman, MH, Ji, J, Luo, Z, Wang, Q, Xiao, H, Wang, K
Water science and technology : a journal of the International Association on Water Pollution Research. 2016;(12):3008-16
Abstract
This study aimed to assess the uptake of diclofenac, a widely used nonsteroidal anti-inflammatory pharmaceutical, by a macrophyte Cyperus alternifolius in a mesocosm-scale free water surface (FWS) constructed wetland. Quantitative analysis of diclofenac concentrations in water solution and plant tissues was conducted by high performance liquid chromatography analysis after sample pre-treatment with solid-phase extraction and liquid extraction, respectively. The FWS with Cyperus alternifolius obtained a maximum 69.3% diclofenac removal efficiency, while a control system without plant only had a removal efficiency of 2.7% at the end of the experiment period of 70 days. Based on mass balance study of the experimental system, it was estimated that plant uptake and in-plant conversion of diclofenac contributed about 21.4% of the total diclofenac removal in the mesocosm while the remaining 78.6% diclofenac was eliminated through biotic and abiotic conversion of diclofenac in the water phase. Diclofenac on the root surface and in roots, stems and leaves of Cyperus alternifolius was found at the concentrations of 0.15-2.59 μg/g, 0.21-2.66 μg/g, 0.06-0.53 μg/g, and 0.005-0.02 μg/g of fresh weight of plant tissues, respectively. The maximum bioaccumulation factor of diclofenac was calculated in roots (21.04) followed by root surface (20.49), stems (4.19), and leaves (0.16), respectively. Diclofenac translocation potentiality from root to stem was found below 0.5, suggesting a slow and passive translocation process of diclofenac. Current study demonstrated high potential of Cyperus alternifolius for phytoremediation of diclofenac in FWS and can be applied in other engineered ecosystems.
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4.
Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components.
Wang, D, Li, Y, Li Puma, G, Wang, C, Wang, P, Zhang, W, Wang, Q
Journal of hazardous materials. 2015;:277-84
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Abstract
The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (˙OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×10(8) M(-1) s(-1)) scavenged reactive oxygen species, Cl(-) (k=-5.3×10(8) M(-1) s(-1)) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca(2+) at concentrations higher than 50 mM (k=-1.3×10(9) M(-1) s(-1)) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3(-) (k=6.9×10(8) M(-1) s(-1)) and CO3(2-) (k=3.7×10(8) M(-1) s(-1)) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO˙ generation. Other ubiquitous secondary effluent components including SO4(2-) (k=3.9×10(5) M(-1) s(-1)), NH3(+) (k=3.5×10(5) M(-1) s(-1)) and Na(+) (k=2.6×10(4) M(-1) s(-1)) had negligible effects. 90% of 17-α-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12 min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water.
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5.
Comparison of denitrification performances using PLA/starch with different mass ratios as carbon source.
Wu, C, Tang, D, Wang, Q, Wang, J, Liu, J, Guo, Y, Liu, S
Water science and technology : a journal of the International Association on Water Pollution Research. 2015;(7):1019-25
Abstract
A suitable carbon source is significant for biological nitrate removal from groundwater. In this study, slow-release carbon sources containing polylactic acid (PLA) and starch at 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 ratios were prepared using a blending and fusing technique. The PLA/starch blend was then used as a solid carbon source for biological nitrate removal. The carbon release rate of PLA/starch was found to increase with increased starch content in leaching experiments. PLA/starch at 5:5 mass ratio was found to have the highest denitrification performance and organic carbon consumption efficiency in semi-continuous denitrification experiments, and was also revealed to support complete denitrification at 50 mg-N/L influent nitrate concentration in continuous experiments. The effluent nitrate concentration was <2 mg NO(3)(-)-N/L, which met the national standard (GB 14848-93) for groundwater. Scanning electron microscopy results further showed that the surface roughness of PLA/starch increased with prolonged experimental time, which may be conducive to microorganism attachment. Therefore, PLA/starch was a suitable carbon source and biofilm carrier for groundwater remediation.
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6.
Modeling of quantitative effects of water components on the photocatalytic degradation of 17α-ethynylestradiol in a modified flat plate serpentine reactor.
Wang, D, Li, Y, Li, G, Wang, C, Zhang, W, Wang, Q
Journal of hazardous materials. 2013;:64-71
Abstract
The effect of water components on the photocatalytic degradation of organic pollutants was incompletely understood, especially in the case of hydroxyl radical (•OH) generation and scavenging. Previous studies have used various methods to determine the rate constants for the reactions between •OH and water components, but the interactions between water components were not taken into concern. In this study, a sequential relative rate technique was used to investigate the effects of water components on the rates of •OH generation and EE2 degradation in a modified flat plate serpentine reactor, including NO₃(-), H₂PO₄(-), SO₄(2-), CO₃(2-), Cl(-), Na(+), Fe(3+), dissolved organic matter (DOM) etc. The results reflected that NO₃(-) and DOM accelerated the photodegradation of 17α-ethynylestradiol (EE2) (3.2% and 21.2%, respectively). Cl(-) and Fe(3+) inhibited that process (5.2% and 3.1%, respectively). Finally, a model for the photocatalytic degradation of EE2 was developed for the first time, taking the obtained rate constants, catalyst concentrations, flow velocities and light intensities into concern. A good agreement was observed between the model and experimental profiles.
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7.
Nitrate removal from groundwater by cooperating heterotrophic with autotrophic denitrification in a biofilm-electrode reactor.
Zhao, Y, Feng, C, Wang, Q, Yang, Y, Zhang, Z, Sugiura, N
Journal of hazardous materials. 2011;(3):1033-9
Abstract
An intensified biofilm-electrode reactor (IBER) combining heterotrophic and autotrophic denitrification was developed for treatment of nitrate contaminated groundwater. The reactor was evaluated with synthetic groundwater (NO(3)(-)-N50 mg L(-1)) under different hydraulic retention times (HRTs), carbon to nitrogen ratios (C/N) and electric currents (I). The experimental results demonstrate that high nitrate and nitrite removal efficiency (100%) were achieved at C/N = 1, HRT = 8h, and I = 10 mA. C/N ratios were reduced from 1 to 0.5 and the applied electric current was changed from 10 to 100 mA, showing that the optimum running condition was C/N = 0.75 and I = 40 mA, under which over 97% of NO(3)(-)-N was removed and organic carbon (methanol) was completely consumed in treated water. Simultaneously, the denitrification mechanism in this system was analyzed through pH variation in effluent. The CO(2) produced from the anode acted as a good pH buffer, automatically controlling pH in the reaction zone. The intensified biofilm-electrode reactor developed in the study was effective for the treatment of groundwater polluted by nitrate.
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8.
Denitrification of nitrate contaminated groundwater with a fiber-based biofilm reactor.
Wang, Q, Feng, C, Zhao, Y, Hao, C
Bioresource technology. 2009;(7):2223-7
Abstract
A fiber-based biofilm reactor was developed using a laboratory-scale apparatus for treatment of nitrate-contaminated groundwater. Denitrification bacteria were inoculated by anaerobic sludge from a wastewater treatment plant. Nitrate removal efficiency, nitrite accumulation, COD and pH in the treated water were investigated under various conditions set by several parameters including hydraulic retention times (HRTs) (24, 20, 16, 12, 8, 4 and 2h), influent nitrate loading (around 50, 100 and 150 NO(3)(-)-N mg L(-1)), pH (5, 6, 7, 8, and 9) and ratios of carbon to nitrogen (C/N=3.00, 2.00, 1.50 1.25 and 1.00). The experimental results demonstrated that the optimum reaction parameters were pH 7-7.5,C/N=1.25 and HRT=8h, under which over 99% of NO(3)(-)-N was removed, almost no NO(2)(-)-N accumulated and COD was nearly zero in treated water when the concentration of NO(3)(-)-N was around 100.00 mg L(-1) in influent.
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Association between arsenic exposure from drinking water and plasma levels of soluble cell adhesion molecules.
Chen, Y, Santella, RM, Kibriya, MG, Wang, Q, Kappil, M, Verret, WJ, Graziano, JH, Ahsan, H
Environmental health perspectives. 2007;(10):1415-20
Abstract
BACKGROUND Epidemiologic studies of cardiovascular disease risk factors and appropriate biomarkers in populations exposed to a wide range of arsenic levels are a public health research priority. OBJECTIVE We investigated the relationship between inorganic arsenic exposure from drinking water and plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule-1 (sVCAM-1), both markers of endothelial dysfunction and vascular inflammation, in an arsenic-exposed population in Araihazar, Bangladesh. METHODS The study participants included 115 individuals with arsenic-related skin lesions participating in a 2 x 2 randomized, placebo-controlled, double-blind trial of vitamin E and selenium supplementation. Arsenic exposure status and plasma levels of sICAM-1 and sVCAM-1 were assessed at baseline and after 6 months of follow-up. RESULTS Baseline well arsenic, a long-term measure of arsenic exposure, was positively associated with baseline levels of both sICAM-1 and sVCAM-1 and with changes in the two markers over time. At baseline, for every 1-mug/L increase in well arsenic there was an increase of 0.10 ng/mL [95% confidence interval (CI), 0.00-0.20] and 0.33 ng/mL (95% CI, 0.15-0.51) in plasma sICAM-1 and sVCAM-1, respectively. Every 1-microg/L increase in well arsenic was associated with a rise of 0.11 ng/mL (95% CI, 0.01-0.22) and 0.17 ng/mL (95% CI, 0.00-0.35) in sICAM-1 and sVCAM-1 from baseline to follow-up, respectively, in spite of recent changes in urinary arsenic as well as vitamin E and selenium supplementation during the study period. CONCLUSIONS The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation that persists over time and also suggest a potential mechanism underlying the association between arsenic exposure and cardiovascular disease.