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Bao Q.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,Zhejiang Provincial Key Laboratory of Water Science and Technology | Tian J.,Tsinghua University | Wang J.,Tsinghua University
Radiation Physics and Chemistry | Year: 2014

Industrial wastewaters containing 2-mercaptobenzothiazole (MBT), a widely used chemical additive, usually cannot be treated properly by conventional biological methods, thus cause an environmental risk. Ionizing radiation was proposed as a method for abatement of several refractory pollutants from water. The paper investigated MBT degradation using irradiation technology. The decomposition kinetics was described, and the transformation and the change of biodegradability were discussed. The results of gamma radiation experiments on MBT-containing aqueous solutions indicated that reactive radicals resulting from water radiolysis effectively degrade MBT and improve the biodegradability of the solutions. At a 20. mg/L MBT concentration, the removal of 82% was achieved at the absorbed dose of 1.2. kGy. The results of specific oxygen uptake rate (SOUR) test showed that MBT was decomposed into biodegradable products, after irradiation at 20. kGy. Radicals attacked the sulfur atoms of the studied molecule leading to the release of sulfate ions, but the mineralization of organic carbons was rather weak. Initial concentration significantly affected the degradation efficacy of MBT by gamma radiation. © 2014 Elsevier Ltd. Source

Liu W.,Tsinghua University | Sang J.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,Yangtze University | And 4 more authors.
Journal of Cleaner Production | Year: 2015

Electric bikes (e-bikes) have developed faster than any other mode of transport in China, which has stimulated the rapid growth of China's lead-acid battery (LAB) industry for more than a decade. This research undertook a life cycle assessment (LCA) for LABs used in e-bikes in China. Its purpose was to identify the key materials and processes that contribute most to impacts on the environment and public health within the life cycle of LABs, from materials extraction and processing, manufacture, transportation, use, and end-of-life. It also sought to find opportunities for improving the environmental profile of LABs. The results indicate that LABs use, as well as materials extraction and processing, have the largest environmental impacts within the life cycle of LABs. The former is responsible for 84% of the primary energy use and contributes the highest potentials to energy-related impacts, including global warming (86%) and acidification (69%). The latter, specifically the lead used in batteries, is the most important driver of impacts such as ozone depletion, photochemical smog, eutrophication, and carcinogenicity. Accordingly, battery reuse after refurbishment and recovery of materials in the end-of-life stage could significantly mitigate most of the overall life cycle impacts by reducing the consumption of virgin materials. However, currently, 95% of total lead emissions are released in the end-of-life stage due to improper management of the spent LABs recycling market in China, and these emissions causes 90% of total human toxicity potential. Battery manufacture only accounts for 3% of total lead emissions after the national cleanup action for heavy metal pollution. Moreover, sensitivity coefficients are employed to evaluate the reliability and uncertainty of the LCA results. Based on the findings, there are several substantial opportunities to further reduce the overall environmental impacts of LABs, such as prolonging the lifetime of LABs, reducing the consumption of metals in LABs, and improving the technology and management in the recovery of spent LABs. © 2015 Elsevier Ltd. Source

Qi B.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,Zhejiang Provincial Key Laboratory of Water Science and Technology | Wang J.,Tsinghua University
Chinese Journal of Environmental Engineering | Year: 2014

To determine the composition of organic pollutants in the cephalosporin synthesis wastewater, the gas chromatography-mass spectrometry (GC-MS) technology was used and the analytical method was optimized. The influent and effluent of the existing treatment system were sampled at a cephalosporin intermediate plant located in Tianjin. The organic matter was extracted from raw wastewater using dichloromethane. After concentration and purification, the samples were injected into the column for separation. The qualitative analysis was made by comparing the obtained mass spectrograms to NIST08 database. Over 30 kinds of organic pollutants were identified and the chemical structure and abundance information of each molecule were provided. After further classification of the listed components, it is concluded that heterocycles and nitrogen-containing polycycles are the most recalcitrant pollutants discharged by the cephalosporin intermediate plant which are supposed to be treated by additional physico-chemical process. ©, 2014, Science Press. All right reserved. Source

Bao Q.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,Zhejiang Provincial Key Laboratory of Water Science and Technology | Wang J.,Tsinghua University
Journal of Environmental Sciences (China) | Year: 2014

Diisopropylthiourea (DPT), an intermediate of a widely used cephalosporin, has been found to be one of the most refractory components in cephalosporin synthesis wastewater. This compound cannot be completely removed by conventional biological processes due to its antimicrobial property. Ionizing radiation has been applied in the decomposition of refractory pollutants in recent years and has proved effective. Therefore, the decomposition of DPT by γ-irradiation was studied. The compound was irradiated at the dose of 150-2000. Gy before a change of concentration and UV absorption of the solutions was detected. Furthermore, the decomposition kinetics and radiation yield (G-value) of DPT was investigated. The results of radiation experiments on DPT-containing aqueous showed that the DPT can be effectively degraded by γ-radiation. DPT concentration decreased with increasing absorbed doses. G-values of radiolytic decomposition for DPT (20. mg/L) were 1.04 and 0.47 for absorbed doses of 150 and 2000. Gy, respectively. The initial concentration and pH of the solutions affected the degradation. As the concentration of substrate increased, the decomposition was reduced. The decrease of removal rate and radiation efficacy under alkaline condition suggested that lower pH values benefit the γ-induced degradation. UV absorption from 190 to 250. nm decreased after radiation while that from 250 to 300. nm increased, indicating the formation of by-products. © 2014 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. Source

Xie Y.,Tsinghua University | Chen L.,Tsinghua University | Chen L.,Zhejiang Provincial Key Laboratory of Water Science and Technology | Liu R.,Zhejiang Provincial Key Laboratory of Water Science and Technology
Chemosphere | Year: 2016

Adsorbable organic halogens (AOX) and total organic carbon (TOC) removal efficiencies in pharmaceutical wastewater treated by Fenton process under response surface methodology (RSM) optimized conditions were studied. High regression coefficient value R2 (R2 = 0.9680, 0.9040 for AOX and TOC removal efficiency, respectively) and low value coefficient of variation (2.21%, 2.04% for AOX and TOC, respectively) of the quadratic model indicated that the model was accurate in predicting the experimental results. The desirability function was used to optimize AOX and TOC removal efficiencies simultaneously. The optimal pH, Fe2+ concentration, molar ratio of H2O2/Fe2+ and reaction time were found to be 3.3, 19.05 mM, 20.16 and 2.2 h, respectively, and 91.78% AOX and 75.01% TOC were removed under these conditions, which was validated. Furthermore, gas chromatography-mass spectrometer (GC-MS) results revealed that 28 out of 33 kinds of organic compounds, including 11 kinds of AOX were completely removed by the Fenton process while one new AOX compound, 4,5,6,7-tetrachlorophthalide, was produced which was the result of the carbonyl of 4,5,6,7-tetrachloro-1,3-isobenzofurandione being attacked in the Fenton reaction. These results indicated that analysis of organics was important since new AOX compounds could be produced in Fenton process despite the value of AOX decreasing. © 2016 Elsevier Ltd. Source

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