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Occurrence of antibiotic resistance genes and bacterial pathogens in water and sediment in urban recreational water

Journal of environmental Sciences 2019年第3期31卷 65-74页

作者： Peiyan Dong Qijia Cui Tingting Fang Yong Huang Hui Wang state key joint laboratory on environment simulation and pollution control School of Environment Tsinghua University

The emergence and prevalence of antibiotic resistance genes(ARGs) and pathogens in the environment are serious global health concern. However, information about the occurrence of ARGs and pathogens in recreational water is still limited. Accordingly, we investigated the occurrence of six ARGs and human pathogens in three recreational lakes, and the correlations between ARGs and one mobile genetic element(intI1) were analyzed. The quantitative PCR results showed that the concentration of ARGs ranged from 4.58 × 10~0 to 5.0 × 10~5 copies/mL in water and from 5.78 × 10~3 to 5.89 × 10~8 copies/g dry weight(dw)in sediment. Sul1 exhibited the highest level among the five quantifiable ARGs. The concentrations of sul1, bla_(-TEM), and tetX exhibited significant positive correlations with intI1(p < 0.05), indicating that intI1 may be involved in their proliferation. The detection frequencies of ARGs ranged from 75%–10~0%, indicating the prevalence of these risks in this region. The concentration of Escherichia coli, Aeromonas spp., Mycobacterium avium,Pseudomonas aeruginosa, and Salmonella enterica ranged from 10~3 to 10~5 copies/10~0 mL in water and 10~4–10~6 copies/g dw in sediment. In total, 25% of the samples harbored all pathogen genes, indicating the prevalence of these pathogens in recreational ***, the next-generation sequencing results showed that 68 genera of pathogens were present, among which Aeromonas, Mycobacterium, and Pseudomonas were the dominant ones in this region, posing a considerable potential health risk to public health. Overall, the widespread distribution of ARGs and pathogens underscores the need to better monitor and mitigate their propagation in recreational lakes and the associated risks to human health.

关键词： Recreational water ARGs Class 1 integron Pathogen diversity and concentration

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Evaluation of oxygen transfer parameters of fine-bubble aeration system in plug flow aeration tank of wastewater treatment plant

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Journal of environmental Sciences 2013年第2期25卷 295-301页

作者： Xiaohong Zhou Yuanyuan Wu Hanchang Shi Yanqing Song state key joint laboratory of environment simulation and pollution control School of EnvironmentTsinghua University

Knowledge of the oxygen mass transfer of aerators under operational conditions in a full-scale wastewater treatment plant （WWTP） is meaningful for the optimization of WWTP, however, scarce to best of our knowledge. Through analyzing a plug flow aeration tank in the Lucun WWTP, in Wuxi, China, the oxygenation capacity of fine-bubble aerators under process conditions have been measured in- situ using the off-gas method and the non-steady-state method. The off-gas method demonstrated that the aerators in different corridors in the aeration tank of WWTP had significantly different oxygen transfer performance; furthermore, the aerators in the same corridor shared almost equal oxygen transfer performance over the course of a day. Results measured by the two methods showed that the oxygen transfer performance of fine-bubble aerators in the aeration tank decreased dramatically compared with that in the clean water. The loss of oxygen transfer coefficient was over 50% under low-aeration conditions （aeration amount 〈 0.67 Nm 3 /hr）. However, as the aeration amount reached 0.96 Nm 3 /hr, the discrepancy of oxygen transfer between the process condition and clean water was negligible. The analysis also indicated that the non-steady-state and off-gas methods resulted in comparable estimates of oxygen transfer parameters for the aerators under process conditions.

关键词： fine-bubble aerator off-gas method non-steady-state method oxygen transfer parameters

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The performance of a combined nitritation–anammox reactor treating anaerobic digestion supernatant under various C/N ratios

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Journal of environmental Sciences 2015年第4期27卷 207-214页

作者： Jian Zhao Jiane Zuo Jia Lin Peng Li state key joint laboratory of environment simulation and pollution control School of Environment Tsinghua University

A combined nitritation–anammox reactor was developed to treat the digestion supernatant under various C/N ratios. Due to the difficulties for heterotroph to utilize the refractory organics, the reactor presented relatively stable performance with increasing supernatant addition. Nevertheless, the adverse effects of supernatant would accumulate during the long-term operation and thus weakened the activity and shock resistance of microbes,which further led to the gradual decrease of reactor performance after 92 days＇ *** this circumstance, supernatant with volatile fatty acids（VFAs） residuals was further introduced into the reactor to investigate the performance of combined nitritation–anammox process with VFA addition. With the appearance of VFAs, the nitrogen removal performance gradually restored and the reactor finally achieved stable and efficient performance with C/N ratio of 0.35. The VFA residuals within 150 mg/L in the supernatant served as the extra electron donors and stimulated the heterotrophic denitrification process, which was vital for the enhancement of reactor. The nitrogen removal rate and total nitrogen removal efficiency reached 0.49 kg N/（m^3·day） and 88.8% after 140 days＇ operation, respectively. The combined nitritation–anammox reactor was proved suitable to treat digestion supernatant.

关键词： Combined nitritation–anammox Anaerobic digestion supernatant C/N ratios Volatile fatty acids

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Monthly survey of N-nitrosamine yield in a conventional water treatment plant in North China

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Journal of environmental Sciences 2015年第12期27卷 142-149页

作者： Chengkun Wang Shuming Liu Jun Wang Xiaojian Zhang Chao Chen School of environment Tsinghua University state key joint laboratory of environment simulation and pollution control (SKLESPC)

A sampling campaign was conducted monthly to investigate the occurrence of N-nitrosamines at a conventional water treatment plant in one city in North *** yield of N-nitrosamines in the treated water indicated precursors changed greatly after the source water *** concentrations of N-nitrosodimethylamine（NDMA）,N-nitrosomorpholine（NMOR）,and N-nitrosopyrrolidine（NPYR） in the finished water were6.9,3.3,and 3.1 ng/L,respectively,from June to October when the Luan River water was used as source water,while those of NDMA,N-nitrosomethylethylamine（NMEA）,and NPYR in the finished water were 10.1,4.9,and 4.7 ng/L,respectively,from November to next April when the Yellow River was *** concentration in the finished water was frequently over the 10 ng/L,i.e.,the notification level of California,USA,which indicated a considerable threat to public *** correlations were observed between N-nitrosamine yield and typical water quality parameters except for the dissolved organic nitrogen.

关键词： N-nitrosamines Precursors Fluorescence excitation-emission matrix Dissolved organic nitrogen Molecule weight Correlation

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Adsorption of chlorophenols from aqueous solutions by pristine and surface functionalized single-walled carbon nanotubes

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Journal of environmental Sciences 2016年第5期28卷 187-198页

作者： Han Ding Xin Li Jun Wang Xiaojian Zhang Chao Chen state key joint laboratory of environmental simulation and pollution control School of Environment Tsinghua University

The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes（SWCNTs） has been investigated. Pseudo-first order and pseudo-second order models were used to describe the kinetic data. All adsorption isotherms were well fitted with Langmuir, Freundlich and Polanyi–Manes models, due to surface adsorption dominating the adsorption process. The close linear relationship between log Kowand log Kdsuggested that hydrophobicity played an important role in the adsorption. The SWCNTs＇ adsorption capacity for chlorophenols was weakened by addition of oxygen-containing functional groups on the surface, due to the loss of specific surface area, the increase of hydrophilicity and the reduction of π–π interaction. The best adsorption capacity of pristine SWCNTs, SWCNT-OH and SWCNT-COOH for six chlorophenols varied from 19 to 84 mg/g, from 19 to 65 mg/g and from 17 to 65 mg/g,respectively. The effect of pH on the adsorption of 2,6-dichlorophenol（2,6-DCP）, was also studied. When p H is over the pK aof 2,6-dichlorophenol（2,6-DCP）, its removal dropped sharply. When ionic strength increased（Na Cl or KCl concentration from 0 to 0.02 mmol/L）,the adsorption capacity of 2,6-DCP on pristine SWCNTs decreased slightly. The comparison of chlorophenols adsorption by SWCNTs, MWCNTs and PAC was made, indicating that the adsorption rate of CNTs was much faster than that of PAC. The results provide useful information about the feasibility of SWCNTs as an adsorbent to remove chlorophenols from aqueous solutions.

关键词： Adsorption Chlorophenols Single-walled carbon nanotubes Isotherms Kinetics Cation–π interaction

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Evaluating the emission status of light-duty gasoline vehicles and motorcycles in Macao with real-world remote sensing measurement

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Journal of environmental Sciences 2014年第11期26卷 2240-2248页

作者： Yu Zhou Ye Wu Shaojun Zhang Lixin Fu Jiming Hao School of environment State Key Joint Laboratory of Environment Simulation and Pollution Control Tsinghua University state environmental Protection key laboratory of Sources and control of Air pollution Complex

Roadside remote sensing measurement was used to explore the real-world emission status of light duty gasoline vehicles （LDGVs） and motorcycles in Macao. Both fuel-based and distance-based emission factors were derived using the mass balance method. The emission concentration profile of LDGVs illustrated the benefits of tightening emission standards at the source country or region of import. The distance-based emission factors for CO, HC and NOx of LDGVs registered before 2000 were 8.00, 1.04 and 1.36 g/km, respectively. The distance-based emission factors for CO, HC and NOx of LDGVs registered in or after 2000 were 1.16, 0.15 and 0.18 g/km, respectively. The fuel-based CO emission factors of light duty motorcycles （LDMCs） and heavy duty motorcycles （HDMCs） registered before 2000 were about 10 times higher than those of LDGVs of the same age group. As the emissions of LDGVs decreased more quickly after 2000, the gap widens for newer vehicles. The distance-based HC emission factors of LDMCs and HDMCs registered before 2000 were 4.81 and 2.91 g/km, respectively. The distance-based HC emission factors of LDMCs and HDMCs registered in or after 2000 were 3.52 and 0.93 g/km, respectively. The poor emission performance of motorcycles and their larger share in the traffic flow will cause them to be the major contributor to traffic CO and HC emissions. LDMCs, especially two-stroke models, should be the priority for vehicle emission control efforts in Macao.

关键词： Emission Remote sensing Macao Motorcycle

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Mesoporous silicas synthesis and application for lignin peroxidase immobilization by covalent binding method

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Journal of environmental Sciences 2013年第1期25卷 181-187页

作者： Zunfang Hu Longqian Xu Xianghua Wen environmental simulation and pollution control state key joint laboratory School of EnvironmentTsinghua University

Immobilization of enzymes on mesoporous silicas （MS） allows for good reusability. MS with two-dimensional hexagonal pores in diameter up to 14.13 nm were synthesized using Pluronic P123 as template and 1,3,5-triisopropylbenzene as a swelling agent in acetate buffer. The surface of MS was modified by the silanization reagents 3-aminopropyltriethoxysilane. Lignin peroxidase （LIP） was successfully immobilized on the modified MS through covalent binding method by four agents： glutaraldehyde, 1,4- phenylene diisothiocyanate, cyanotic chloride and water-soluble carbodiimide. Results showed that cyanotic chloride provided the best performance for LiP immobilization. The loaded protein concentration was 12.15 mg/g and the immobilized LiP activity was 812.9 U/L. Immobilized LiP had better pH stability. Acid Orange II was used to examine the reusability of immobilized LiP, showing more than 50% of the dye was decolorized at the fifth cycle.

关键词： mesoporous silica lignin peroxidase covalent binding stability

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Strategies to improve aerobic granular sludge stability and nitrogen removal based on feeding mode and substrate

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Journal of environmental Sciences 2019年第10期31卷 144-154页

作者： Quan Yuan Hui Gong Hao Xi Heng Xu Zhengyu Jin Nasir Ali Kaijun Wang state key joint laboratory of environment simulation and pollution control School of EnuironmentTsinghua Uniuersity

A systemic strategy was proposed to improve aerobic granular sludge(AGS)stability and nitrogen(N)removal efficiency by optimizing feeding mode and substrate aiming at complicated wastewater *** functional groups at the genus level identified by high-throughput sequencing were evaluated as *** results showed that anaerobic feeding mode and acetate promoted the compact AGS formation with excellent total nitrogen(TN)removal efficiency(averaging 91.7%±4.1%)at various dissolved oxygen *** the aerobic feeding mode led to a loose AGS structure with a vulnerable anaerobic core and poor TN removal efficiency(averaging58.8%±7.4%).Simultaneous nitrification and denitrification process played the dominant role in N removal in compact AGS over the alternating nitrification and denitrification ***-concentration glucose undermined feast-famine condition with filamentous bacteria growth out of granule and decreased TN removal efficiency to 67.3%±15.2%.Lower food to microorganism ratio may result in a lower N removal rate attributed to the sharply increased biomass concentration fed by ***-oxidizing bacteria,nitrite-oxidizing bacteria,denitrifying bacteria,and denitrifying phosphorus accumulation organisms enriched during AGS granulation also contributed to the efficient N *** proposed strategy provided insights into the relationship between various factors and stable AGS formation,and systemic operation methods for various complicated wastewater treatment.

关键词： Aerobic granular sludge Feeding mode Substrate N removal Stability

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Factors influencing water quality indices in a typical urban river originated with reclaimed water

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Frontiers of environmental Science & Engineering 2017年第4期11卷 73-82页

作者： Jiao Zhang Zhen Wei Haifeng Jia Xia Huang state key joint laboratory of environment simulation and pollution control School of Environment Tsinghua University Beijing 100084 China

The water quality in a typical urban river segment originated with reclaimed water in Beijing was monitored for two years to investigate the evolution of water quality along the rivcr, and statistical analysis was applied to determine factors influencing water quality of such river recharged by reclaimed water. It was found that no significant change in pollutant concentrations （including COD, NH4＋-N, TN and TP） was observed during this time, and their average values were close to those of the original reclaimed water. However, turbidity and algal contents fluctuated temporally in the direction of river flow. Statistical analysis showed that turbidity was strongly positively correlated with algal contents for flow rate 〈 0.1 m.s-1. whereas it was strongly positively correlated with both algalcontents and TOC for flow rate 〉 0. 1m. s-1. It was observed that diatom was the absolute predominant phyla with Melosira as the major species. In terms of algal bloom control, the specific growth rate of algae was strongly correlated to temperature, and was influenced by flow rate as well. Compared with two other rivers originated with reclaimed water and one originated with natural water, the Shannon Wiener index in the objective river was the lowest, with values between 0.7 and 1.6, indicating a high risk for algal bloom. Statistics showed that Shannon Wiener index was strongly negatively correlated to nutrient salts and cations.

关键词： Reclaimed water Urban river Turbidity Algae Flow rate

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Performance and mechanism for cadmium and lead adsorption from water and soil by corn straw biochar

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Frontiers of environmental Science & Engineering 2017年第2期11卷 157-164页

作者： Tong Chi Jiane Zuo Fenglin Liu state key joint laboratory of environment simulation and pollution control School of Environment Tsinghua University Beijing 100084 China

Cadmium （Cd） and lead （Pb） in water and soil could be adsorbed by biochar produced from corn straw. Biochar pyrolyzed under 400℃ for 2 h could reach the ideal removal efficiencies （99.24% and 98.62% for Cd and Pb, respectively） from water with the blochar dosage of 20 g. L^-1 and initial concentration of 20 mg.L^-1 . The pH value of 4-7 was the optimal range for adsorption reaction. The adsorption mechanism was discussed on the basis of a range of characterizations, including X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, Fourier transform infrared spectroscopy （FTIR） and Raman analysis; it was concluded as surface complexation with active sorption sites （-OH, -COO-）, coordination with 7c electrons （C = C, C = O） and precipitation with inorganic anions （OH-, CO3^2- , SO4^2- ） for both Cd and Pb. The sorption isotherms fit Langmuir model better than Freundlich model and the saturated sorptlon capacities for Cd and Pb were 38.91 mg·g^-1 and 28.99 mg.g^-1 , espectwely. When mixed with soil, biochar could effectively increase alkalinity and reduce bioavailability of heavy metals. Thus, biochar derived from corn straw would be a green material for both removal of heavy metals and amelioration of soil.

关键词： Corn strawBiocharHeavy metalsSorption isothermBioavailability

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