长江流域城市水污染治理成效的系统评估与解析

如何实现人类社会经济的可持续发展是本世纪的重大挑战之一。近几十年来,中国经济实力大幅提升,国际影响力显著增强。然而,经济社会高速发展可能会给生态环境造成诸多不利影响,其中之一就是人类活动污水排放总量的快速增长。长江经济带作为中国高质量发展的重点区域,科学评估和揭示沿江城市群污水治理成效及影响因素至关重要。本研究核算了2007-2017年间长江流域主要污染物的浓度变化趋势,利用数据驱动型技术对影响污染物通量变化的关键因子及其贡献开展了系统解耦和量化分析,揭示了污染物排放强度的时空异质性,解析了沿江城镇污水系统发展对污染物通量削减的作用效果。研究发现,长江流域水污染治理成效总体向好,长江经济带国内生产总值和沿江人类活动污水排放强度之间的强耦合在2013年之后呈现脱钩趋势,这主要得益于城镇排水和污水厂基础设施建设的快速发展。研究提出,长江流域城镇污水治理如何实现以水载资源再生利用为导引的“绿色零碳模式”转变,对于全面改善长江流域的水环境质量具有关键作用,同时也能为区域生态环境保护与经济高质量发展提供有益启示和借鉴。

Production of propene from 1-butene metathesis reaction on tungsten based heterogeneous catalysts

A new propene production route from 1-butene metathesis has been developed on heterogeneous 10WO3/Al2O3-HY catalysts with different HY contents.It is found that the catalysts play bi-functionally first for the isomerization of 1-butene to 2-butene and then for the cross-metathesis between 1-butene and 2-butene to propene and 2-pentene.The combination of HY zeolite and Al2O3 is prerequisite for the production of propene.The propene yield keeps increasing with the HY content in the range of 10-70 wt%,where 10WO3/Al2O3-70HY exhibits the highest propene yield.The MS-H2-TPR and MS-O2-TPO characterizations indicate that the increase of HY content in the catalysts weakens the interaction between W species and supports,whereas enhance the probability of coking on the metal species and acid sites.

Science and Technology for Combating Global Water Challenges

The survival and development of human society highly depends on the water availability. Driven by the growth of population and economy, global water demand has increased more than eightfold since the 1900s. Meanwhile, the commonly deteriorated freshwater quality cause a large proportion of available water resources unsuitable for human uses. This inter-coupled challenge of insufficient water quantity and inadequate water quality has rendered water scarcity a widespread problem in many parts of the world.

A Cast Copper Rotor Induction Motor for Small Commercial EV Traction: Electromagnetic Design, Analysis, and Experimental Tests

According to the demands of the small commercial electric vehicle(EV)traction driving system,an 18kW inverter-driven induction motor(IM)with a die-casting copper squirrel cage rotor for traction drive was designed and evaluated.The 2D finite element model of the designed IM was built by considering the nonlinearity of core materials,and the geometric parameters of the motor were optimized.The operational performance of torque versus speed characteristics and the efficiency over the speed range under the rated(continuous)and overload condition were investigated.Finally,the designed inverter-driven IM was developed and the performance of the IM operating in three typical modes were tested respectively.The experimental results of the designed motor operating in various driven mode were compared with that of 2D FEM.All the results proved that the designed inverter-driven IM could meet the target specification of the small commercial EV.

Arrayed Cobalt Phosphide Electrocatalyst Achieves Low Energy Consumption and Persistent H2 Liberation from Anodic Chemical Conversion

Electrochemical reduction of water to hydrogen(H2) offers a promising strategy for production of clean energy,but the design and optimization of electrochemical apparatus present challenges in terms of H2 recovery and energy consumption.Using cobalt phosphide nanoarrays(Co2 P/CoP NAs) as a charge mediator,we effectively separated the H2 and O2 evolution of alkaline water electrolysis in time,thereby achieving a membrane-free pathway for H2 purification.The hierarchical array structure and synergistic optimization of the electronic configuration of metallic Co2 P and metalloid CoP make the Co2 P/CoP NAs high-efficiency bifunctional electrocatalysts for both charge storage and hydrogen evolution.Theoretical investigations revealed that the introduction of Co2 P into CoP leads to a moderate hydrogen adsorption free energy and low water dissociation barrier,which are beneficial for boosting HER activity.Meanwhile,Co2 P/CoP NAs with high capacitance could maintain a cathodic H2 evolution time of 1500 s at 10 mA cm^(-2) driven by a low average voltage of 1.38 V.Alternatively,the energy stored in the mediator could be exhausted via coupling with the anodic oxidation of ammonia,whereby only 0.21 V was required to hold the current for 1188 s.This membrane-free architecture demonstrates the potential for developing hydrogen purification technology at low cost.

Array Antenna Pattern Synthesis Based on Selective Levy Flight Culture Wolf Pack Algorithm

Due to the shortcomings such as the premature convergence and the bad local optimal searching capability in traditional intelligence methods for pattern synthesis,a new type of wolf pack algorithm named Levy⁃Cultural Wolf Pack Algorithm(LCWPA)was designed on the basis of the Cultural Wolf Pack Algorithm(CWPA),which obeys the selective Levy flight.Because of the good overall management ability provided by the cultural algorithm in optimization process and the characteristics of excellent population diversity brought by Levy flight,the search efficiency of the new algorithm was greatly improved.When the algorithm was applied in the pattern synthesis of array antenna,the simulation results showed its high performance with multi⁃null and low side⁃lobe restrictions.In addition,the algorithm was superior to the Quantum Particle Swarm Optimization(QPSO),Particle Swarm Optimization(PSO),and Genetic Algorithm(GA)in optimization accuracy and operation speed,and is of very good generalization.

Performance Evaluation of a 60kW IPM Motor for Medium Commercial EV Traction Application

This paper presented the design and performance analysis of a 60kW interior permanent-magnet(IPM)synchronous motor used as traction drive in a medium commercial electric vehicle(EV),according to the traction requirements of the electric vehicle under the rated operating conditions and overload conditions.The key dimensions were calculated on the basis of the permanent-magnet(PM)motor theory,and the 2D finite element method(FEM)simulation model of the IPM motor was built by using 2D Maxwell software.The influence geometric structures of the IPM motor including the PM dimensions and skewed PMs on electromagnetic torque were investigated,and the temperature distribution of the motor under rated operating condition and the condition of maximum speed were calculated.Finally,the simulation results of the IPM motor running in various operating modes were compared with the experimental results,which demonstrated that the designed IPM motor can match all requirements of the medium commercial electric vehicle driving applications.

降碳减污多维协同的基础科学问题

基于第325期“双清论坛”,本文总结了我国降碳减污领域所面临的国家重大需求,回顾了降碳减污领域近年来所取得的主要研究进展,分析了相关基础研究的问题与不足,凝炼了该领域未来5~10年的重大关键科学问题,探讨了前沿研究方向和科学基金资助策略。

Removal of pharmaceutical in a biogenic/chemical manganese oxide system driven by manganese-oxidizing bacteria with humic acids as sole carbon source

Bioaugmented sand filtration has attracted considerable attention because it can effectively remove contaminants in drinking water without additional chemical reagent addition.In this study,a synthesized chemical manganese dioxide (MnO_(2)) -coated quartz sand(MnQS) and biogenic manganese oxide (BioMnOx) composite system was proposed to simultaneously remove typical pharmaceutical contaminants and Mn_(2)+.We demonstrated a manganese-oxidizing bacterium,Pseudomonas sp.QJX-1,could oxidize Mn_(2)+to generate BioMnOxusing humic acids (HA) as sole carbon source.The coaction of MnQS,QJX-1,and the generated BioMnOxin simultaneously removing caffeine and Mn_(2)+in the presence of HA was evaluated.We found a synergistic effect between them.MnQS and BioMnOxtogether significantly increased the caffeine removal efficiency from 32.8%(MnQS alone) and 21.5%(BioMnOxalone) to 61.2%.Meanwhile,Mn_(2)+leaked from MnQS was rapidly oxidized by QJX-1 to regenerate reactive BioMnOx,which was beneficial for continuous contaminant removal and system stability.Different degradation intermediates of caffeine oxidized by MnQS and BioMnOxwere detected by LC-QTOF-MS analysis,which implied that caffeine was oxidized by a different pathway.Overall,this work promotes the potential application of bioaugmented sand filtration in pharmaceutical removal in the presence of natural organic matter in drinking water.

A hybrid fuel cell for water purification and simultaneously electricity generation

The development of highly efficient energy conversion technologies to extract energy from wastewater is urgently needed,especially in facing of increasing energy and environment burdens.Here,we successfully fabricated a novel hybrid fuel cell with BiOCl-NH_(4)PTA as photocatalyst.The polyoxometalate(NH_(4)PTA)act as the acceptor of photoelectrons and could retard the recombination of photogenerated electrons and holes,which lead to superior photocatalytic degradation.By utilizing BiOCl-NH_(4)PTA as photocatalysts and Pt/C air-cathode,we successfully constructed an electron and mass transfer enhanced photocatalytic hybrid fuel cell with flow-through field(F-HFC).In this novel fuel cell,dyes and biomass could be directly degraded and stable power output could be obtained.About 87%of dyes could be degraded in 30 min irradiation and nearly 100%removed within 90 min.The current density could reach up to~267.1μA/cm^(2);with maximum power density(Pmax)of~16.2μW/cm^(2) with Rhodamine B as organic pollutant in F-HFC.The power densities were 9.0μW/cm^(2),12.2μW/cm^(2),and 13.9μW/cm^(2) when using methyl orange(MO),glucose and starch as substrates,respectively.This hybrid fuel cell with BiOCl-NH_(4)PTA composite fulfills the purpose of decontamination of aqueous organic pollutants and synchronous electricity generation.Moreover,the novel design cell with separated photodegradation unit and the electricity generation unit could bring potential practical application in water purification and energy recovery from wastewater.

Removal characteristics of microplastics by Fe-based coagulants during drinking water treatment

Microplastics have caused great concern worldwide recently due to their ubiquitous presence within the marine environment. Up to now, most attention has been paid to their sources,distributions, measurement methods, and especially their eco-toxicological effects. With microplastics being increasingly detected in freshwater, it is urgently necessary to evaluate their behaviors during coagulation and ultrafiltration(UF) processes. Herein, the removal behavior of polyethylene(PE), which is easily suspended in water and is the main component of microplastics, was investigated with commonly used Fe-based salts. Results showed that although higher removal efficiency was induced for smaller PE particles, low PE removal efficiency(below 15%) was observed using the traditional coagulation process, and was little influenced by water characteristics. In comparison to solution pH, PAM addition played a more important role in increasing the removal efficiency, especially anionic PAM at high dosage(with efficiency up to 90.9%). The main reason was ascribed to the dense floc formation and high adsorption ability because of the positively charged Fe-based flocs under neutral conditions. For ultrafiltration, although PE particles could be completely rejected,slight membrane fouling was caused owing to their large particle size. The membrane flux decreased after coagulation; however, the membrane fouling was less severe than that induced by flocs alone due to the heterogeneous nature of the cake layer caused by PE, even at high dosages of Fe-based salts. Based on the behavior exhibited during coagulation and ultrafiltration, we believe these findings will have potential application in drinking water treatment.

Removal of tetracycline from water by Fe-Mn binary oxide

Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments.A series of FeMn binary oxide with different Fe:Mn molar ratios was synthesized by a simultaneous oxidation and coprecipitation process for TC removal.Results showed that Fe-Mn binary oxide had higher removal efficiency than that of hydrous iron oxide and hydrous manganese oxide,and that the oxide with a Fe:Mn molar ratio of 5:1 was the best in removal than other molar ratios.The tetracycline removal was highly pH dependent.The removal of tetracycline decreased with the increase of initial concentration,but the absolute removal quantity was more at high concentration.The presence of cations and anions such as Ca2+,Mg2+,CO32-and SO42-had no significant effect on the tetracycline removal in our experimental conditions,while SiO32-and PO43-had hindered the adsorption of tetracycline.The mechanism investigation found that tetracycline removal was mainly achieved by the replacement of surface hydroxyl groups by the tetracycline species and formation of surface complexes at the water/oxide interface.This primary study suggests that Fe-Mn binary oxide with a proper Fe:Mn molar ratio will be a very promising material for the removal of tetracycline from aqueous solutions.

Factors associated with fatigue in acquired immunodeficiency syndrome patients with antiretroviral drug adverse reactions: a retrospective study

OBJECTIVE: To retrospectively study the prevalence of fatigue and factors associated with fatigue among acquired immunodeficiency syndrome (AIDS) patients with antiretroviral drug adverse re-ctions. METHODS: Data were collected from case reportforms (CRFs) for a project funded by the 11th National 5-year Special Science and Technology Program on Major Infectious Diseases. Fatigue was defined by patient self-report. The outcomes were the prevalence of fatigue and the potential risk factors of fatigue. Univariate and multivariate logistic regression analyses were conducted to identify the factors associated with fatigue. RESULTS: Among the 228 subjects, the prevalence of fatigue was 86.8%. In univariate analysis, the significant differences in demographic characteristics between patients with and without fatigue were: gender [OR=2.29; 95% CI (1.05-4.98)], education level [OR=0.40; 95% CI (0.18-0.85)], anemia [OR=3.80; 95% CI (1.27-11.31)], time of HIV diagnosis [OR= 0.29; 95% CI (0.13-0.65)], and route of infection [OR= 0.14; 95% CI (0.06-0.32)]. Abnormal taste and rapid pulse were more commonly seen in patients with fatigue (P<0.05), while abdominal distension and lumbar soreness were encountered less often in patients with fatigue (P<0.05). Multivariate analysis showed that the four main factors associated with fatigue were anemia [OR=3.50; 95% CI (1.01-12.15)], route of infection [OR=3.40; 95% CI (1.21-9.58); P= 0.02<0.05], lumbar soreness [OR=0.06; 95% CI (0.02-0.18); P=0.000<0.05], and rapid pulse [OR= 10.58; 95% CI (2.16-51.75); P=0.004<0.05]. CONCLUSION: This study demonstrated that fa- tigue is common (86.8% prevalence) in AIDS patients with antiretroviral drug adverse reactions, and that anemia, route of infection (i.e., non-commercial blood donation) and rapid pulse were risk factors, while lumbar soreness was a protective factor related to fatigue. More attention should bepaid to fatigue and more efforts should be made to find ways to prevent, control and eliminate this symptom in AIDS patients with antiretroviral drug adverse reactions.

Effects of protein properties on ultrafiltration membrane fouling performance in water treatment

Protein-like substances always induce severe ultrafiltration(UF) membrane fouling. To systematically understand the effect of proteins, regenerated cellulose UF membrane(commonly used for protein separation) performance was investigated in the presence of bovine serum albumin(BSA) under various water conditions. Results showed that although trypsin enhanced the membrane flux via proteolysis, catalysis took a long time. Membrane fouling was alleviated at high solution p H and low water temperature owing to the strong electrostatic repulsion force among BSA molecules. Both Na^+ and Ca^(2+)could increase membrane flux. However, Ca^(2+)played a bridging role between adjacent BSA molecules,whereas membrane fouling was alleviated via a hydration repulsion force with Na+. The order of influence on membrane fouling was as follows: Ca^(2+)concentration > Na+concentration > pH > temperature > trypsin concentration. Furthermore, a polyvinylidene fluoride UF membrane experiment showed that Ca^(2+)could reduce the fouling induced by BSA. Thus, the differences in UF membrane performance will have application potential for alleviating UF membrane fouling induced by proteins during water treatment.

Comparison of the effects of aluminum and iron(Ⅲ)salts on ultrafiltration membrane biofouling in drinking water treatment

Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances(EPS). To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration(UF)membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al_2(SO_4)_3·18 H_2O performed better in reducing membrane fouling due to the slower growth rate of microorganisms. In comparison to Al_2(SO_4)_3·18H_2O,more EPS were induced with Fe_2(SO_4)_3·x18H_2O, both in the membrane tank and the sludge on the cake layer. We also found that bacteria were the major microorganisms, of which the concentration was much higher than those of fungi and archaea. Further analyses showed that Proteobacteria was dominant in bacterial communities, which caused severe membrane fouling by forming a biofilm, especially for Fe_2(SO_4)_3·x18H_2O. Additionally, the abundances of Bacteroidetes and Verrucomicrobia were relatively higher in the presence of Al_2(SO_4)_3·18 H_2O,resulting in less severe biofouling by effectively degrading the protein and polysaccharide in EPS. As a result, in terms of microorganism behaviors, Al-based salts should be given preference as coagulants during actual operations.

Enhanced phosphate removal using zirconium hydroxide encapsulated in quaternized cellulose

Zirconium-based materials are efficient adsorbent for aqueous phosphate removal.However,current zirconium-based materials still show unsatisfied performance on adsorption capacity and selectivity.Here,we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose(QC-Zr) for the selective phosphate removal.Zirconium hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional(3D) cross-linked cellulose chains.The maximum P adsorption capacity of QC-Zr was 83.6 mg P/g.Furthermore,the QC-Zr shows high P adsorption performance in a wide pH range,generally due to the electrostatic effects of quaternized cellulose.The enhanced adsorption of P was also achieved in the presence of competing anions(including Cl^-,NO3^-,SO4^2-,SO4^4-) and humic acid(HA) even at a molar ratio up to 20 levels.The column adsorption capacity of QC-Zr reached 4000 bed volumes(BV) at EBCT=0.5 min as the P concentration decreased from 2.5 to 0.5 mg/L.Mechanism study revealed that both-N^+(CH3)3 groups and zirconium hydroxide were involved in phosphate adsorption via electrostatic interactions between -N^+(CH3)3 and phosphate,and the formation of zirconium hydrogen phosphate(Zr(HPO4)x).The 31 P nuclear magnetic resonance(NMR) study implied that P surface-precipitated and inner-sphere complexed with zirconium hydroxide at a ratio of 3:1.

Preferential binding between intracellular organic matters and Al_(13) polymer to enhance coagulation performance

Coagulation is the best available method for removing intracellular organic matter(IOM),which is released from algae cells and is an important precursor to disinfection by-products in drinking water treatment. To gain insight into the best strategy to optimize IOM removal, the coagulation performance of two Al salts, i.e., aluminum chloride(AlCl_3) and polyaluminum chloride(PACl, containing 81.2% Al_(13)), was investigated to illuminate the effect of Al species distribution on IOM removal. PACl showed better removal efficiency than AlCl_3 with regard to the removal of turbidity and dissolved organic carbon(DOC), owing to the higher charge neutralization effect and greater stability of pre-formed Al_(13) species. High pressure size exclusion chromatography analysis indicated that the superiority of PACl in DOC removal could be ascribed to the higher binding affinity between Al_(13) polymer and the low and medium molecular weight(MW) fractions of IOM. The results of differential log-transformed absorbance at 254 and 350 nm indicated more significant formation of complexes between AlCl_3 and IOM, which benefits the removal of tryptophan-like proteins thereafter. Additionally,PACl showed more significant superiority compared to AlCl_3 in the removal of <5 kD a and hydrophilic fractions, which are widely viewed as the most difficult to remove by coagulation.This study provides insight into the interactions between Al species and IOM, and advances the optimization of coagulation for the removal of IOM in eutrophic water.

The effects of hydrogen peroxide pre-oxidation on ultrafiltration membrane biofouling alleviation in drinking water treatment

Pre-oxidation is widely used to reduce ultrafiltration membrane fouling.However,the variation in the composition of microbial communities and extracellular polymeric substances(EPSs) accompanying pre-oxidation in drinking water treatment has received little attention.In this study,hydrogen peroxide(H_2O_2) was used in a coagulationultrafiltration process with Al_2(SO_4)_3·18H_2O.A long-term reactor experiment(60 d) showed that pre-oxidation alleviated membrane fouling,mainly due to its inhibition of microbial growth,as observed by flow cytometry measurements of the membrane tank water.Further analysis of the formed cake layer demonstrated that the corresponding levels of EPS released from the microbes were lower with than without H_2O_2 treatment.In comparison to polysaccharides,proteins dominated the EPS.2 D-electrophoresis showed little difference(p > 0.05,Student's t-test) in the composition of proteins in the cake layer between the treatments with and without H_2O_2.The molecular weights of proteins ranged from approximately 30–50 kDa and the majority of isoelectric points ranged from 6 to 8.Highthroughput sequencing showed that the predominant bacteria were Proteobacteria,Bacteroidetes,and Verrucomicrobia in both cake layers.However,the relative abundance of Planctomycetes was higher in the cake layer with H_2O_2 pre-oxidation,which was likely probably due to the strong oxidative resistance of its cell wall.Overall,our findings clarify the fundamental molecular mechanism in H_2O_2 pre-oxidation for ultrafiltration membrane bio-fouling alleviation in drinking water treatment.

Selection of water source for water transfer based on algal growth potential to prevent algal blooms

Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential(AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources(Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen(TN) and total phosphorus(TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.