Construction and mechanistic insights of a novel ZnO functionalized rGO composite for efficient adsorption and reduction of Cr(VI).

A series of ZnO decorated reduced graphene oxide (rGO) (ZnrGOx) with different doping ratios were synthesized by the alkaline hydrothermal method using graphene oxide (GO) and Zn(NO3)2·6H2O as precursors, and subsequently used for the adsorption study of Cr(VI) in water. The morphology, crystalline phase structure, and surface elemental properties of ZnrGOx composites were revealed by XRD, SEM, BET, FT-IR, and XPS characterizations. The results showed that ZnO nanoparticles can be clearly seen on the surface of layered rGO. Meanwhile, as the doping rate increased, the C = C double bonds were broken and more carboxylic acid groups formed in ZnrGOx. In addition, the ZnrGO0.1 composite had the most excellent adsorption performance and good stability, and reusability. The adsorption removal rate of Cr(VI) can reach 99%, and the maximum adsorption amount of Cr(VI) was 68.9655 mg/g in 3 h. The isothermal and kinetic model simulations showed that Cr(VI) adsorption on ZnrGO0.1 composite is a chemical adsorption process, spontaneous and endothermic. Based on the concentrations of different valence states of Cr in the solid and liquid phases, 40% of Cr(VI) was reduced to Cr(III) on the surface of ZnrGO0.1 composite. Moreover, the adsorption-reduction mechanisms of Cr(VI) on ZnrGO0.1 composite were further elucidated. The ZnrGO0.1 composite manifested great potential as an efficient adsorbent for Cr(VI) removal.

Facilitated catalytic ozonation of atrazine over highly stabilized Zn-Al layered double oxides composites: efficacy and mechanism.

A series of Zn-Al Layered Double Oxides (ZnAl-LDO) composites were prepared by the hydrothermal and calcination method via employing the Zn-Al Layered Double Hydroxide (ZnAl-LDH) as the precursors in the present study. The structural properties and the catalytic ozonation activity of ZnrAl-T composites synthesized with different Zn/Al molar ratios and calcination temperatures were systematically investigated. Diversified characterizations were applied to analyze the phase structure and chemical composition of ZnrAl-T composites. As the calcination temperature increased, the layered ZnAl-LDH structure could be entirely destroyed and the crystallinity gradually improved. With the Zn/Al mole ratio of 4.0 and calcination temperature of 500°C, the Zn4Al-500 composite obtained the outstanding catalytic ozonation performance for atrazine (ATZ) degradation with the pseudo-first-order constant of 0.5080 min-1, which was 5 times more than that in O3 alone. Meanwhile, the ATZ degradation efficiency was gradually enhanced from 44.1% to 99.9% within 3.0 min when the solution pH ranged from 3.0 to 10.0. Besides, the Zn4Al-500 composite exhibited splendid stability over multiple reaction cycles. In addition, the radical scavenging test and electron spin resonance measurement demonstrated that superoxide radical and hydroxyl radical are the dominant reactive species in O3/Zn4Al-500 process. Moreover, nineteen and ten transformation products were detected in O3 alone and O3/Zn4Al-500 process, and possible degradation pathways of ATZ were further elucidated. Overall, the Zn4Al-500 composite would provide a potential alternative for pollutants removal due to its high catalytic ozonation efficiency, stability, and reusability.

Catalytic ozonation oxidation of ketoprofen by peanut shell-based biochar: effects of the pyrolysis temperatures.

A series of peanut shell (HS)-based biochar were prepared at different pyrolysis temperatures and subsequently used as the effective ozonation catalysts for ketoprofen (KET) degradation in aqueous solution. The physicochemical properties and morphology of the obtained biochar were analysed by ICP, TG, XRD, FT-IR, SEM, TEM, BET and etc. characterizations. The results demonstrated that the pyrolysis temperature played an important role on the structure and morphology of HS-based biochar. As the pyrolysis temperature increased, the cellulose and hemicellulose of HS gradually decomposed, resulting in the loss of biochar mass, improvement of the surface roughness, the increase of specific surface area, and the formation of new functional groups. The HS-based biochar pyrolyzed at 600°C (HS600) achieved the fast KET degradation rate with the pseudo-first-order rate constant of 0.922 min-1 and the low adsorption rate of 1.3% in O3/HS600 process. Meanwhile, the effects of the HS600 dosage, initial KET concentration, temperature, water matrix, and solution pH on KET degradation were systematically evaluated. Besides, the HS600 displayed great stability and reusability towards KET degradation during multiple cycling experiments. Moreover, the single oxygen, superoxide radical and hydroxyl radical were involved in O3/HS600 process and the mechanisms for the improvement of KET degradation were also elucidated. It could be speculated that the enhancement of the catalytic ozonation by HS-based biochar was probably attributed to the increased active sites and the intense chemical bonds, and delocalized π electron.

Reduction of bromate by zero valent iron (ZVI) enhances formation of brominated disinfection by-products during chlorination.

Bromate (BrO3-) is a predominant undesired toxic disinfection by-product (DBP) during ozonation of bromide-containing waters. The reduction of BrO3- by zero valent iron (ZVI) and its effect on formation of organic halogenated DBPs during chlorination were investigated in this study. The presence of ZVI could reduce BrO3- to bromide (Br-), and Br- formed could be transformed to free bromine (HOBr/OBr-) during chlorination, further leading to organic brominated (Br-) DBPs formation. Formation of DBPs during chlorination, including trihalomethanes (THMs) and haloacetonitriles (HANs) was detected under different conditions. The results showed that when ZVI dosage increased from 0 to 1 g L-1, the formation of Br-DBPs (e.g., TBM and DBCM) was significantly improved, while the formation of Cl-DBPs (e.g., TCM, TCAN and DCAN) reduced. Higher ZVI dosage exhibited inhibitory effect on Br-DBPs formation due to the competition between ZVI and free chlorine (HOCl/OCl-). The bromine substitution factor (BSF) of THMs significantly decreased from 0.61 ± 0.06 to 0.22 ± 0.02, as the pH was raised from 5.0 to 9.0. Besides, the increase of initial BrO3- concentration significantly improved the formation of Br-DBPs and decreased the formation of Cl-DBPs, leading to an obvious rise on the BSF of THMs. As the initial concentration of HOCl increased, all THMs and HANs gradually increased. Moreover, the analysis based on the cytotoxicity index (CTI) of the determined DBPs showed that reduction of BrO3- by ZVI during chlorination had certain risks in real water sources, which should be paid attention to in the application.

Study on the adsorption and desorption performance of magnetic resin for Congo red.

This study was to evaluate the adsorption capability of a magnetic resin (NDMP) to the removal of Congo red (CR) from aqueous solution. The adsorption kinetic and isotherm of NDMP were studied, as well as the desorption performance of NDMP. The results showed that the adsorption process of NDMP on CR was more suitable for Pseudo-second-order kinetic model. The whole adsorption process was affected by intraparticle diffusion and ion exchange. The adsorption isotherm of CR by NDMP was fitted better with Langmuir model. It showed that the adsorption of CR on NDMP resin was single layer adsorption. The maximum adsorption capacity (Qm) of CR at 308 K can reach 354.29 mg/g. In the desorption, 10% NaCl and NaOH eluents had better desorption rate for CR than other mass fraction. While NaCl(10%)-MeOH mixed eluent with volume ratio of 3:7 had the best regeneration performance. The desorption rate can reach 90% within 30 min. The adsorption performance of NDMP on CR didn't decrease after 13 times successive adsorption-desorption by NaCl(10%)-methanol eluent, indicating that NDMP can be efficiently regenerated. The excellent adsorption-desorption performance of NDMP on CR suggests that the magnetic resin has a great potential for treating CR dye wastewater.

Synergistic mechanism and degradation kinetics for atenolol elimination via integrated UV/ozone/peroxymonosulfate process.

The present research systematically investigates the atenolol (ATL) degradation in integrated UV/Ozone (O3)/peroxymonosulfate (PMS) process focusing on the synergistic mechanism, reaction kinetics, pollutant degradation pathway and antibacterial activity. The results manifested that the integrated UV/O3/PMS process showed the noteworthy superiority to ATL degradation compared with UV/PMS, UV/O3 and O3/PMS systems. Simultaneously, the impacts of operating parameters like PMS dosage, initial ATL concentration, solution pH and water matrix were comprehensively explored. The ATL elimination efficiency increased linearly with PMS dose and significantly enhanced in alkaline conditions. The •OH and SO4•- were the primary reactive radicals for ATL oxidation in UV/O3/PMS system based on the radical scavenging experiments and electron paramagnetic resonance characterization. Besides, a simplified kinetic model on the basis of the dominant reactions and the steady-state assumption was established to foretell the relative contributions of reactive oxidants for ATL elimination in UV/O3/PMS process. Main transformation products were determined via UPLC-QTOF-MS to infer the possible degradation pathways of ATL. Furthermore, the UV/O3/PMS process could distinctly mitigate the antibacterial activity of ATL and its intermediates to E. coli and B. subtilis. Our findings may have critical implications for the development of novel oxidation processes for recalcitrant contaminants mitigation in water purification.

Construction of Ag2O-modified g-C3N4 photocatalyst for rapid visible light degradation of ofloxacin.

The design of stable and highly efficient photocatalysts had emerged as an economic and promising way for eliminating harmful pharmaceutical pollutants. In this study, a series of Ag2O-modified g-C3N4 composites with different Ag2O amounts (denoted as Ag2O-CNx) were fabricated via a facile reflux condensation methodology. Ofloxacin (OFL) was chosen as a model pollutant to evaluate the degradation efficiency of the photocatalytic system. The optimal photocatalytic activity was achieved with Ag2O-CN1.0, which reached up to 99.1% removal of OFL after 15-min reaction and the pseudo-first-order constant was 0.469 min-1, approximately 42 times higher than that of g-C3N4. Considering the complexity of the actual environment, the important influential factors such as catalyst dosage, initial OFL concentration, solution pH, and natural organic matter on the OFL degradation were systematically investigated. Additionally, Ag2O-CN1.0 showed good stability and recyclability in multiple cycle experiments. The feasible photodegradation mechanism of OFL was proposed with radical scavenger experiments, and the degradation products were determined. Furthermore, the enhanced photocatalytic activity could be ascribed to not only the high photogenerated charge separation efficiency and the surface plasmon resonance effect of metallic Ag, but also the p-n heterojunction formed between Ag2O and g-C3N4. Therefore, Ag2O-CN1.0 was a treatment material possessing great application prospects for eliminating OFL in wastewater.

Kinetic and mechanistic insights into the abatement of clofibric acid by integrated UV/ozone/peroxydisulfate process: A modeling and theoretical study.

The feasibility of integrated UV/ozone (O3)/peroxydisulfate (PDS) process for abatement of clofibric acid (CA) was systematically explored in this study with focus on the kinetic simulation and oxidation mechanisms. The results indicated the UV/O3/PDS process was of prominent treatment capability with pseudo-first-order rate constant of CA degradation increased by 65.9% and 86.0% compared to UV/O3 and UV/PDS processes, respectively. A chemical kinetic model was developed and successfully employed to predict CA elimination as well as the specific contributions of UV, hydroxyl radical (•OH) and sulfate radical (SO4•-) under different PDS dosage, pH, natural organic matters, bicarbonate and chloride conditions in UV/O3/PDS process. According to quantum chemical calculation, radical addition on ortho site of isopropoxy substituent and single electron transfer were corroborated to be the dominant reaction channels for the oxidation of CA by •OH and SO4•-, respectively. Additionally, the reactive sites and transformation pathways of CA were proposed via Fukui function calculation and UPLC-Q-TOF-MS analysis. Moreover, the performance of UV/O3/PDS process was further evaluated with regard to the energy demand and bromate formation. This study first proposed a kinetic model in UV/O3/PDS process and elucidated the regioselectivity and products distribution of CA during oxidative treatment.

Band gap tuning of g-C3N4 via decoration with AgCl to expedite the photocatalytic degradation and mineralization of oxalic acid.

A series of functional organic-metal AgCl-decorated graphitic carbon nitride (AgCl-CNx) composites were synthesized and applied for the degradation of oxalic acid (OA) under visible light. The highest photocatalytic activity was achieved with AgCl decoration ratio of 1.0 (denoted as AgCl-CN1.0). The pseudo-first-order constant for OA degradation was 0.0722 min-1 with the mineralization efficiency of 90.80% after 60 min reaction in the photocatalytic process with AgCl-CN1.0. A variety of characterization techniques including Brunauer-Emmett-Teller, X-ray diffraction, scanning electron microscope, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, ultraviolet-visible diffuse reflectance spectra, photoluminescence, and Mott-Schottky were utilized to elucidate the physicochemical, microstructure, and optical properties contributing to the improvement of the photocatalytic performance. The results showed that AgCl-CN1.0 had an oblate flaky erythrocyte-like structure with a moderate band gap energy of ~3.00 eV. In addition, the effects of the key parameters (i.e., AgCl-CN1.0 dosage, initial OA concentration, solution pH, and presence of natural organic matter) on OA degradation were systematically investigated. Radical scavenger experiments indicated that photogenerated holes, electrons, superoxide anion radicals, and hydroxyl radicals were the dominant reactive species. Moreover, AgCl-CN1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag+ release in the solution over multiple reaction cycles. The efficient OA mineralization could be mainly ascribed to the moderate specific surface area, increased numbers of active sites, and effective interfacial charge transfer of AgCl-CN1.0. Overall, the AgCl-CN1.0 composite was demonstrated to be a highly efficient, stable, and recoverable photocatalyst.

Insights into the activation of ozonation by hydroxylamine: Influential factors, degradation mechanism and reaction kinetics.

The decontamination of prometon (PMT) by ozone/hydroxylamine hydrochloride (O3/HAC) was systematically investigated in this study with focus on the degradation mechanism and kinetics. Experimental results revealed that there was an enhancement of PMT degradation efficiency by 42.1% and the pseudo-first-order rate constant by more than 5.7 times in O3/HAC process under low HAC dosage (5 mg L-1) after 3 min in comparison with O3 alone. The second-order rate constant of PMT with hydroxyl radical (•OH) was determined to be (1.84 ± 0.1) × 109 M-1 s-1 and 7.80 × 109 M-1 s-1 via competition kinetics and •OH steady-state hypothesis, respectively. The PMT removal in O3/HAC process was highly pH-dependent and the optimum degradation performance was achieved under pH 5.0. In addition, •OH and singlet oxygen were identified as the primary reactive oxygen radicals in O3/HAC process. Meanwhile, eleven transformation products of PMT were identified and possible degradation mechanisms were proposed. Moreover, a kinetic model based on chemical kinetics and steady-state hypothesis was developed and modified to predict the PMT abatement in O3/HAC process. The results demonstrated that the O3/HAC process provided a promising alternative for refractory organic pollutants decontamination in water treatment.

Enhanced catalytic ozonation towards oxalic acid degradation over novel copper doped manganese oxide octahedral molecular sieves nanorods.

A series of copper doped manganese oxide octahedral molecular sieves (Cu-OMSx-T) with different Cu/Mn ratios and hydrothermal temperatures were successfully synthesized and used for catalytic ozonation towards oxalic acid (OA) degradation. The as-prepared Cu-OMSx-T composites were comprehensively investigated by BET, FT-IR, XPS and etc. characterizations. The results indicated that the Cu doping would increase the specific surface area, change chemical bonds, and promote the transformation of multivalent metals and the generation of oxygen vacancies. It was noteworthy that the hydrothermal temperature played an important role in the morphology of Cu-OMSx-T composites and the Cu/Mn molar ratios greatly influenced the catalytic activities. Amongst, the Cu-OMS0.5-140 achieved the optimum catalytic activity with 97.3% of OA degradation efficiency and 98.8% of mineralization rate in 30 min at pH 6.0. Moreover, hydroxyl radical and superoxide radical were identified as the major reactive radicals and the catalytic mechanism for OA degradation enhancement was also elucidated. In addition, the Cu-OMS0.5-140 exhibited great stability and reusability with high OA mineralization rate (>90%) and low metal release after five times recycle. Overall, the results indicated that the synthesized Cu-OMS0.5-140 is an efficient, stable, and recyclable ozonation catalyst, and could be a promising alternative material for water purification.

Efficient enhancement of ozonation performance via ZVZ immobilized g-C3N4 towards superior oxidation of micropollutants.

A functional organic-metal composite material zero-valent zinc immobilized graphitic carbon nitride (ZVZ-g-C3N4) was prepared by a fast and facile two-step synthetic approach with an optimal ZVZ content of 5.4 wt%. The structure, surface morphology and chemical composition of the as-synthesized ZVZ-g-C3N4 were characterized by BET surface area, XRD, FT-IR, SEM, TEM, and XPS, respectively. ZVZ-g-C3N4 composite exhibited superior catalytic ozonation activity with an improvement of 61.2% on atrazine (ATZ) degradation efficiency in 1.5 min reaction, more than 12 times of the pseudo-first-order rate constant, and almost 16-fold of the Rct value obtained in O3/ZVZ-g-C3N4 process compared to O3 alone. Meanwhile, the ATZ degradation efficiency was gradually enhanced with increasing ZVZ-g-C3N4 dosage and initial solution pH in the range from 3.0 to 9.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 1 to 10 mg L-1. The enhanced catalytic ozonation activity of ZVZ-g-C3N4 is attributed to the synergistic effects among ZVZ, ZnO and g-C3N4, as well as the improved dispersibility, increased surface area, and intensive electron-transfer ascribed to the electronic and surface properties modification. The radical scavengers experiments demonstrated that O2-, OH, and 1O2 were the dominant reactive radical species in the multifunctional processes. Moreover, an empirical kinetic model was proposed to predict ATZ degradation. The results indicated that the ZVZ-g-C3N4 composite was a highly efficient, recoverable, and durable catalyst, which would provide a promising alternative in catalytic ozonation.

Occurrence, removal and risk of organic micropollutants in wastewater treatment plants across China: Comparison of wastewater treatment processes.

This study investigated the occurrence, removal and risk of 42 organic micropollutants (MPs), including 30 pharmaceuticals and personal care products and 12 endocrine disrupting chemicals, in 14 municipal wastewater treatment plants (WWTPs) distributed across China. The composition profiles of different MP categories in the influent, effluent, and excess sludge were explored and the aqueous removal efficiencies of MPs were determined. Quantitative meta-analysis was performed to compare the efficacies of different wastewater treatment processes in eliminating MPs. Results indicate that different MP categories showed quite similar distributions among the studied WWTPs, with phenolic estrogenic compounds (PEs), macrolides, and fluoroquinolones being always dominant in the influent, effluent and excess sludge. Tetracyclines, bezafibrate, caffeine, steroid estrogens, and PEs showed high and stable aqueous removal efficiencies, whereas other MPs showed considerably varied aqueous removal efficiencies. Anaerobic/anoxic/oxic process combined with a moving-bed biofilm reactor achieved the highest aqueous removal of MPs among various secondary treatment processes. A combined process consisting of ultrafiltration, ozonation and ClO2 disinfection resulted in the highest removal of MPs among the tertiary treatment processes. Sulfamethoxazole, ofloxacin, ciprofloxacin, clarithromycin, erythromycin, estrone, and bisphenol A in the effluent, as well as ß-estradiol 3-sulfate in the excess sludge could pose high risks. This study draws an overall picture about the current status of MPs in WWTPs across China and provides useful information for better control of the risks associated with MPs.

Enhanced ozonation degradation of atrazine in the presence of nano-ZnO: Performance, kinetics and effects.

Enhanced ozonation degradation of atrazine (ATZ) with nano-ZnO (nZnO) as catalyst and the influences of the operational parameters have been investigated through semi-continuous experiments in this study. The results demonstrated that the combination of ozone (O3) and nZnO showed an obvious synergetic effect and the ATZ degradation conformed to pseudo-first-order kinetics. An improvement of ATZ degradation efficiency by 41.8% and pseudo-first-order rate constant by more than a factor of four was obtained in the O3/nZnO process after 5min of reaction compared to O3 alone. Meanwhile, the degradation efficiency of ATZ was gradually enhanced with increasing nZnO dosage and initial pH in the range from 3.0 to 8.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 0.5 to 5mg/L. Additionally, sulfate ion, chloride ion, nitrate ion and low concentrations of humic acid substances led to enhancement of the ATZ degradation. The notable decrease of ATZ removal efficiency observed in the presence of radical scavengers and the results of free radical tests indicated that OH is the dominant active radical species. The mechanism investigation demonstrated that the enhancement effect could be attributed to the introduction of nZnO, which could promote the utilization of O3, enhance the formation of superoxide radical, and further accelerate the production of hydrogen peroxide and the generation of OH/O2-.

Transformation and fate of natural estrogens and their conjugates in wastewater treatment plants: Influence of operational parameters and removal pathways.

Natural estrogens (NEs) discharged from wastewater treatment plants (WWTPs) have drawn great attention because of their potential risks to aquatic ecosystems. However, neglect of the conjugated natural estrogens (C-NEs) has caused large discrepancies among different studies on the removal of NEs in WWTPs. The present work investigated the transformation and fate of three NEs and six corresponding C-NEs along wastewater treatment processes. The removal efficiencies of the target estrogens (i.e., NEs and C-NEs) and their correlations with the operational parameters were determined over a twelve-month monitoring period at a typical WWTP adopting a combined bio-treatment process (i.e., anaerobic/anoxic/oxic process followed by a moving-bed biofilm reactor). The concentration variations of the target estrogens along the treatment processes were examined to differentiate the transformation and fate of NEs and C-NEs. Moreover, lab-scale experiments were conducted to clarify the removal pathways of C-NEs in the bio-treatment process. Results indicate that both NEs and C-NEs could pass through the treatment processes, thus being frequently detected in the effluent and excess sludge. The aqueous removal efficiencies of NEs and C-NEs were significantly correlated with the sludge retention time and temperature, respectively. C-NEs were more persistent than NEs, so considerably high conjugated ratios (13.5-100.0%) were detected in the effluent. Sulfate conjugates presented a lower adsorption affinity to sludge and a slower hydrolysis rate than glucuronide conjugates, which makes the former more recalcitrant to biodegradation. This study highlights the challenge on the elimination of NEs, particularly their conjugates, by wastewater treatment processes.

Occurrence and removal of antibiotics in ecological and conventional wastewater treatment processes: A field study.

The occurrence and removal of 19 antibiotics (including four macrolides, eight sulfonamides, three fluoroquinolones, three tetracyclines, and trimethoprim) were investigated in two ecological (constructed wetland (CW) and stabilization pond (SP)) and two conventional wastewater treatment processes (activated sludge (AS) and micro-power biofilm (MP)) in a county of eastern China. All target antibiotics were detected in the influent and effluent samples with detection frequencies of >90%. Clarithromycin, ofloxacin, roxithromycin and erythromycin-H2O were the dominant antibiotics with maximum concentrations reaching up to 6524, 5411, 964 and 957 ng/L, respectively; while the concentrations of tiamulin, sulfamerazine, sulfathiazole, sulfamethazine, sulfamethizole and sulfisoxazole were below 10 ng/L. Although the mean effluent concentrations of target antibiotics were obviously lower than the influent ones (except ciprofloxacin), their removals were usually incomplete. Principal component analysis showed that the AS and CW outperformed the MP and SP processes and the AS performed better than the CW process in terms of antibiotics removal. Both the AS and CW processes exhibited higher removal efficiencies in summer than in winter, indicating biological degradation could play an important role in antibiotics removal. Because of the incomplete removal, the total concentration of detected antibiotics increased in the mixing and downstream sections of a local river receiving the effluent from a typical wastewater treatment facility practicing AS process. Nowadays, ecological wastewater treatment processes are being rapidly planned and constructed in rural areas of China; however, the discharge of residual antibiotics to the aquatic environment may highlight a necessity for optimizing or upgrading their design and operation.

Simultaneous detection of endocrine disrupting chemicals including conjugates in municipal wastewater and sludge with enhanced sample pretreatment and UPLC-MS/MS.

The co-existence of free and conjugated estrogens and the interference from complex matrices often lead to largely variable detected concentrations and sometimes even negative removal efficiencies of typical endocrine disrupting chemicals (EDCs) in wastewater treatment plants (WWTPs). In this study, a highly selective and sensitive method was developed for simultaneous extraction, elution, and detection of 12 EDCs (i.e., 4 free estrogens, 6 conjugated estrogens, and 2 phenolic compounds) in municipal wastewater and sludge. Sample pretreatment and ultra-performance liquid chromatography-tandem mass spectrometry detection were optimized to improve the detection selectivity and sensitivity. The results indicate that the additional purification process was highly effective in reducing the matrix interference, and the limits of quantification reached as low as 0.04-2.2 ng L(-1) in wastewater and 0.05-4.9 ng g(-1) in sludge for all target EDCs. The developed method was successfully applied to explore the behavior of target EDCs in a local WWTP. The conjugates occupied a considerable portion (4.3-76.9% in molar ratio) of each related estrogen in the influent. Most of the target EDCs could not be completely removed in WWTPs, thus posing a potential threat to aquatic ecosystems.

Distribution, mass load and environmental impact of multiple-class pharmaceuticals in conventional and upgraded municipal wastewater treatment plants in East China.

The occurrence, fate and environmental impact of 30 pharmaceuticals including sulfonamides, fluoroquinolones, tetracyclines, macrolides, dihydrofolate reductase inhibitors, ß-blockers, antiepileptics, lipid regulators, and stimulants were studied in two municipal wastewater treatment plants (WWTPs) located in Wuxi City, East China. A total of 23 pharmaceuticals were detected in wastewater samples, with a maximum concentration of 16.1 µg L(-1) (caffeine) in the influent and 615.5 ng L(-1) (azithromycin) in the effluent; 19 pharmaceuticals were detected in sludge samples at concentrations up to 12.13 mg kg(-1), with ofloxacin, azithromycin and norfloxacin being the predominant species. Mass balance analysis showed that biodegradation primarily accounted for the removal of sulfonamides, most of the macrolides, and other miscellaneous pharmaceuticals, while adsorption onto the sludge was the primary removal pathway for fluoroquinolones, tetracylines, and azithromycin during biological treatment. The total mass loads of target pharmaceuticals per capita in the two WWTPs were in the ranges of 2681.8-4333.3, 248.0-416.6 and 214.6-374.5 µg per day per inhabitant in the influent, effluent and dewatered sludge, respectively. The upgraded Plant A adopting the combined anaerobic/anoxic/oxic and moving bed biofilm process exhibited a much higher removal of target pharmaceuticals than the conventional Plant B adopting the C-Orbal oxidation ditch process. The concentration levels of sulfamethoxazole, ofloxacin, ciprofloxacin and clarithromycin in the effluent, ofloxacin in the sludge, and the mixture of all target pharmaceuticals in both effluent and sludge posed a high risk to algae in aquatic environments.

Rapid detection of multiple class pharmaceuticals in both municipal wastewater and sludge with ultra high performance liquid chromatography tandem mass spectrometry.

This work described the development, optimization and validation of an analytical method for rapid detection of multiple-class pharmaceuticals in both municipal wastewater and sludge samples based on ultrasonic solvent extraction, solid-phase extraction, and ultra high performance liquid chromatography-tandem mass spectrometry quantification. The results indicated that the developed method could effectively extract all the target pharmaceuticals (25) in a single process and analyze them within 24min. The recoveries of the target pharmaceuticals were in the range of 69%-131% for wastewater and 54%-130% for sludge at different spiked concentration levels. The method quantification limits in wastewater and sludge ranged from 0.02 to 0.73ng/L and from 0.02 to 1.00µg/kg, respectively. Subsequently, this method was validated and applied for residual pharmaceutical analysis in a wastewater treatment plant located in Beijing, China. All the target pharmaceuticals were detected in the influent samples with concentrations varying from 0.09ng/L (tiamulin) to 15.24µg/L (caffeine); meanwhile, up to 23 pharmaceuticals were detected in sludge samples with concentrations varying from 60ng/kg (sulfamethizole) to 8.55mg/kg (ofloxacin). The developed method demonstrated its selectivity, sensitivity, and reliability for detecting multiple-class pharmaceuticals in complex matrices such as municipal wastewater and sludge.

[Aerobic granular sludge bulking due to the lack of nutrient and its recovery].

Under 5 m(COD)/m(N)/m(P) ratios, the shape, settle ability and organic removal performance of aerobic granules were investigated in 5 identical SBRs. The performance of aerobic granules bulking and its recovery methods were also analysed based on SVI30 value. The results indicated that when m(COD)/m(N)/m(P) was 100/5.8/1.2, the granules had integral and dense structures with the SVI30 of 15 - 30 mL x g(-1) and COD removal of above 90%. The system operated stably without any bulking. When m (COD)/m(N)/m(P) was 100/3/0.6 and 100/1.9/0.4, although the granules disintegration was observed, SVI30 was lower than 35 mLx g(-1) and the granules had no bulking, and high COD removal was keeping at above 85%. When m(COD)/m (N)/m(P) was 100/ 0.5/0.1 and 100/0/0, the SVI30 in both systems reached 150 mL x g(-1), and the granules was hard to settle due to sludge bulking in both systems. There is a significant difference of COD removal rate in two systems. The former COD removal rate stayed at 65% -80% in late experiment, while the latter COD removal was quite low during the early operation and finally reduced to about 10% until the system broke down. Aerobic granule bulking due to the lack of N and P could be recovered by adding sufficient nutrient to the systems. After 48 cycles' operation, granules settle ability and organic removal were fully recovered, however there was no obvious recovery on granules morphology except for the color.