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Effect of nitrobenzene on the performance and bacterial community in an expanded granular sludge bed reactor treating high-sulfate organic wastewater

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Frontiers of Environmental Science & Engineering 2019年第1期13卷 63-72页

作者： Jun li Wentao li Gan Luo Yan li aimin li State Key Laboratory of Pollution Control and Resources Reuse School of the Environment Nanjing University Nanjing 210023 China Nanjing University & Yancheng Academy of Environmental Protection Technology and Engineering Yancheng 224000 China

Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO4^2-/gVSS/d to 30.78 mg SO4^2-/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bcicteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Finnicutes for the dominance in response to the increase of influent NB *** genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.

关键词： Nitrobenzene (NB) Sulfate-reducing bacteria (SRB) Bacterial community Sulfate reduction High-throughput sequencing

Selection of magnetic anion exchange resins for the removal of dissolved organic and inorganic matters

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Journal of Environmental Sciences 2012年第11期24卷 1891-1899页

作者： Qiongjie Wang aimin li Jinnan Wang Chengdong Shuang State Key Laboratory of Pollution Control and Resources Reuse School of the EnvironmentNanjing UniversityNanjing 210046China

Four magnetic anion exchange resins （MAERs） were used as adsorbents to purify drinking water. The effect of water quality （pH, temperature, ionic strength, etc.） on the performance of MAER for the removal of dissolved organic matter （DOM） was also investigated. Among the four studied MAERs, the strong base resin named NDMP- 1 with high water content and enhanced exchange capacity exhibited the highest removal rate of dissolved organic carbon （DOC）（48.9% removal rate） and UV-absorbing substances （82.4% removal rate） with a resin dose of 10 mL/L after 30 rain of contact time. The MAERs could also effectively remove inorganic matter such as sulfate, nitrate and fluoride. Because of the higher specific UV absorbance （SUVA） value, the DOM in the raw water was found to be removed more effectively than that in the clarified water by NDMP resin. The temperature showed a weak influence on the removal of DOC from 6 to 26℃, while a relatively strong one at 36℃. The removal of DOM by NDMP was also affected to some extent by the pH value. Moreover, increasing the sulfate concentration in the raw water could decrease the removal rates of DOC and UV-absorbing substances.

关键词： magnetic anion exchange resins dissolved organic matter inorganic anions water quality

Application of a green coagulant with PACl in efficient purification of turbid water and its mechanism study

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Journal of Environmental Sciences 2019年第7期31卷 168-180页

作者： Yuxiang Xue Zhouzhou liu aimin li Hu Yang State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride(PACl) were extensively evaluated for various addition sequences in the coagulation of both raw(surface water from the Jiuxiang River) and synthetic turbid water(two kaolin suspensions with different initial turbidities).Two typical cationic starch-based coagulants with different structures(St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.

关键词： Cationic starch-based green coagulants Polyaluminum chloride Combined coagulation Synergistic coagulation effects Synergistic mechanisms

Adsorption characterizations of fulvic acid fractions onto kaolinite

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Journal of Environmental Sciences 2008年第5期20卷 528-535页

作者： li aimin XU Minjuan li Wenhui WANG Xuejun DAI Jingyu College of Environmental Science Peking University Beijing 100871 China. College of Resources and Environmental Sciences Nanjing Agricultural University Nanjing 210095 China

Fulvic acids extracted from a typical rice-production region near Taihu Lake of China were fractionated into three fractions including F4.8, F7.0 and F11.0 （eluted by pH 4.8 buffer, pH 7.0 buffer and pH 11.0 buffer, respectively）. Sorption of fulvic acid （FA） fractions onto kaolinite was studied by batch adsorption experiments, and characterizations of kaolinite before and after adsorption were investigated using scanning electron microscopy （SEM）. Adsorption isotherms of kaolinite for three FA fractions fit well with the Langrnuir adsorption model. The adsorption density of the three fractions was positively correlated with the ratio of the amount of the alkyl carbon to that of carboxyl and carbonyl carbon in FA fractions and followed an order of F11.0 〉 F7.0 〉 F4.8. Hydrophobic interaction was one of the control mechanisms for the sorption of FA fraction onto kaolinite. SEM images confirmed that compared to blank kaolinite samples, kaolinite samples coated by a FA fraction displayed an opener and more dispersed conformation resulting from the disruption of the floc structure in complex. Dispersion of kaolinite after adsorption was due to the repulsion between negatively charged FA-coated particles, which is closely related to the amount of FA fractions absorbed on kaolinite.

关键词： fulvic acid (FA) fractions kaolinite adsorption scanning electron microscopy (SEM)

Efficient removal of Cr(Ⅲ)-carboxyl complex from neutral and high-salinity wastewater by nitrogen doped biomass-based composites

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Chinese Chemical Letters 2023年第1期34卷 397-402页

作者： li Song Shichao Jing Yixing Qiu Fuqiang liu aimin li State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

Heavy metals usually exist stably as the species of organic complexes in high-salinity ***,their effective removal is challenging,especially when the initial p H is ***,a novel nitrogen doped biomass-based composite(N-CMCS)was synthesized to remove the complexed heavy metal of Cr(Ⅲ)-*** maximum adsorption capacity of Cr(Ⅲ)-Citrate(Cr-Cit)by N-CMCS under neutral p H(7.0)and high-salinity(200 mmol/L NaCl)condition was up to 2.50 mmol/*** the removal performance remained stable after 6 times of *** with species and characterizations analysis,electrostatic attraction and hydrogen bonding were the main mechanisms for N-CMCS to remove Cr(Ⅲ)-carboxyl *** adsorption indicated N-CMCS column could treat about 1300BV simulated wastewater and 350 BV actual wastewater with the concentration of effluent lower than1.0 mg/***,N-CMCS could remove a variety of complexed heavy metal ions under neutral p H,indicating the great potential in practical application.

关键词： Biomass-based Nitrogen doping Adsorption Complexed heavy metals High-salinity wastewater

Efficient removal of chlorophenols from water with a magnetic reduced graphene oxide composite

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Science China Chemistry 2016年第3期59卷 350-359页

作者： Han Yan Qing Du Hu Yang aimin li Rongshi Cheng State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing210023China

A magnetic reduced graphene oxide composite(MRGO) was successfully prepared by a simple and green method. MRGO was then used as an adsorbent and found to exhibit enhanced removal efficiency for various chlorophenols(CPs) from water compared with its precursors, graphene oxide(GO) and reduced graphene oxide. The CPs were o-chlorophenol, p-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. Among them, 2,4,6-trichlorophenol, which exhibited the lowest water solubility and highest molecular weight, most easily bound to MRGO. The preferential interactions between MRGO and CPs were hydrophobic interactions(?-? stacking and hydrophobic effect). This result was confirmed by the equilibrium adsorption behavior in which isotherms were all well described by Freudlich model, indicating heterogeneous and multilayer adsorption. Therefore, CP adsorption was more favored under neutral and acidic conditions, and the decreased removal efficiency of MRGO at higher p H levels was due to the improved hydrophilicity of CPs for deprotonation effect. Moreover, MRGO showed fast removal of each CP, achieving adsorption equilibrium within 10.0 min, presented efficient separation from water under an external magnetic field, and was easily regenerated using dilute Na OH aqueous solution after reaching saturated adsorption. Adsorption capacity of the regenerated MRGO had almost no loss until after five cycles. In summary, MRGO was an efficient adsorbent for the removal of various CPs and had considerable application potential in water treatment.

关键词： magnetic reduced graphene oxide composite green preparation method chlorophenol adsorption mechanism

Factors influencing antibiotics adsorption onto engineered adsorbents

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Journal of Environmental Sciences 2013年第7期25卷 1291-1299页

作者： Mingfang Xia aimin li Zhaolian Zhu Qin Zhou Weiben Yang State Key Laboratory of Pollution Control and Resources Reuse School of the Environment Nanjing University General Office of Lake Taihu Water Pollution Prevention and Control of Jiangsu Province School of Chemistry and Materials Science Nanjing Normal University

The study evaluated the adsorption of two antibiotics by four engineered adsorbents （hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes （MWCNT）） from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaCl 2 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.

关键词： adsorption resin carbon nanotubes pore size surface area

Control strategies for disinfection byproducts by ion exchange resin,nanofiltration and their sequential combination

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Frontiers of Environmental Science & Engineering 2023年第10期17卷 89-101页

作者： Yufeng liao Mengmeng Tang Mengyuan li Peng Shi aimin li Yangyang Zhang Yang Pan State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China

Disinfection byproducts (DBPs) are emerging pollutants in drinking water with high health risks. Precursor reduction before disinfection is an effective strategy to control the formation of DBPs. In this study, three types of anion exchange resins (AERs) and two types of nanofiltration (NF) membranes were tested for their control effects on DBP precursors, DBPs, and total organic halogen (TOX). The results showed that, for AER adsorption, the removal efficiencies of DBP precursors, DBPs, and TOX increased with the increase of resin dose, and the strong basic macroporous anion exchange resin (M500MB) had the highest removal efficiencies. For NF, the highest removal efficiencies were achieved at an operating pressure of 4 bar, and the membrane (NF90) with a smaller molecular weight cut-off, had a better control efficiency. However, AER adsorption was inefficient in removing dissolved organic carbon (DOC);NF was inefficient in removing Br− resulting in insufficient control of Br-DBPs. Accordingly, a sequential approach of AER (M500MB) adsorption followed by NF (NF90) was developed to enhance the control efficiency of DBPs. Compared with single AER adsorption and single NF, the sequential approach further increased the removal efficiencies of DOC by 19.4%–101.9%, coupled with the high Br− removal efficiency of 92%, and thus improved the reduction of cyclic DBPs and TOX by 3.5%–4.9%, and 2.4%–8.4%, respectively;the sequential approach also reduced the cytotoxicity of the water sample by 66.4%.

关键词： Disinfection byproducts Control Anion exchange resin Nanofiltration Cytotoxicity

Hot deformation characteristics and hot working window of as-cast large-tonnage GH3535 superalloy ingot

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Journal of Materials Science & Technology 2018年第12期34卷 2439-2446页

作者： Yao Wang Junsong Wang Jiasheng Dong aimin li Zhijun li Guang Xie Langhong Lou Superalloys Division Institute of Metal ResearchChinese Academy of Sciences Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences College of Materials Science and Chemical Engineering Harbin Engineering University Technology Center Fushun Special Steel Shares Co.LTD. Thorium Molten Salts Reactor Center Shanghai Institute of Applied PhysicsChinese Academy of Sciences

Deformation characteristics and range of optimized hot working parameters of a 6.5 tons GH3535 superalloy ingot with an average columnar grain size of over 1 mm in diameter were investigated. Axial compression experiments were performed in temperature range of 900-1240 ℃ and strain rate range of 0.001-30 s;at a total strain of 0.8. The hot deformation activation energy of the experimental GH3535 alloy is calculated to be 483.22 kJ/mol. Furthermore, the deformation constitutive equation is established by the peak stresses obtained from the stress-strain curves under various conditions. The hot working window of the alloy ingot at a strain of 0.8 can be preliminarily discussed based on the deformed microstructures and processing maps. The optimized hot working window was thus determined at the strain of 0.95 for 6.5 tons GH3535 alloy ingot by the supplementary compression tests. A large-size GH3535 superalloy ring with a dimension of 03010 mm x 410 mm was ultimately manufactured.

关键词： Ni-base superalloy Dynamic recrystallization Hot working Large-tonnage ingot Processing map