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Characteristics and removal mechanism of the precursors of N-chloro-2,2-dichloroacetamide in a drinking

《环境科学与工程前沿（英文）》 2021年第15卷第5期 doi: 10.1007/s11783-020-1338-6

摘要：

• N-Cl-DCAM, an emerging N-DBP in drinking water was investigated.

关键词： N-chloro-2 2-dichloroacetamide Liquid chromatography with tandem mass spectrometry Precursors Removal efficiency Ozonation integrated with biological activated carbon

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Identification of important precursors and theoretical toxicity evaluation of byproducts driving cytotoxicity

Qian-Yuan Wu, Yi-Jun Yan, Yao Lu, Ye Du, Zi-Fan Liang, Hong-Ying Hu

《环境科学与工程前沿（英文）》 2020年第14卷第2期 doi: 10.1007/s11783-019-1204-6

摘要： • NOM formed more C-DBPs while amino acids formed more N-DBPs during chlorination • Aspartic acid and asparagine showed the highest toxicity index during chlorination • Dichloroacetonitrile might be a driving DBP for cytotoxicity and genotoxicity • Dichloroacetonitrile dominated the toxicity under different chlorination conditions Chlorination, the most widely used disinfection process for water treatment, is unfortunately always accompanied with the formation of hazardous disinfection byproducts (DBPs). Various organic matter species, like natural organic matter (NOM) and amino acids, can serve as precursors of DBPs during chlorination but it is not clear what types of organic matter have higher potential risks. Although regulation of DBPs such as trihalomethanes has received much attention, further investigation of the DBPs driving toxicity is required. This study aimed to identify the important precursors of chlorination by measuring DBP formation from NOM and amino acids, and to determine the main DBPs driving toxicity using a theoretical toxicity evaluation of contributions to the cytotoxicity index (CTI) and genotoxicity index (GTI). The results showed that NOM mainly formed carbonaceous DBPs (C-DBPs), such as trichloromethane, while amino acids mainly formed nitrogenous DBPs (N-DBPs), such as dichloroacetonitrile (DCAN). Among the DBPs, DCAN had the largest contribution to the toxicity index and might be the main driver of toxicity. Among the precursors, aspartic acid and asparagine gave the highest DCAN concentration (200 g/L) and the highest CTI and GTI. Therefore, aspartic acid and asparagine are important precursors for toxicity and their concentrations should be reduced as much as possible before chlorination to minimize the formation of DBPs. During chlorination of NOM, tryptophan, and asparagine solutions with different chlorine doses and reaction times, changes in the CTI and GTI were consistent with changes in the DCAN concentration.

关键词： Chlorination Dichloroacetonitrile Aspartic acid Asparagine Toxicity index

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Removal of organic matter and disinfection by-products precursors in a hybrid process combining ozonation

Xiaojiang FAN,Yi TAO,Dequan WEI,Xihui ZHANG,Ying LEI,Hiroshi NOGUCHI

《环境科学与工程前沿（英文）》 2015年第9卷第1期页码 112-120 doi: 10.1007/s11783-014-0745-y

摘要： The performance of an integrated process including coagulation, ozonation, ceramic ultrafiltration (UF) and biologic activated carbon (BAC) filtration was investigated for the removal of organic matter and disinfection by-products (DBPs) precursors from micro-polluted surface water. A pilot scale plant with the capacity of 120 m per day was set up and operated for the treatment of drinking water. Ceramic membranes were used with the filtration area of 50 m and a pore size of 60 nm. Dissolved organic matter was divided into five fractions including hydrophobic acid (HoA), base (HoB) and neutral (HoN), weakly hydrophobic acid (WHoA) and hydrophilic matter (HiM) by DAX-8 and XAD-4 resins. The experiment results showed that the removal of organic matter was significantly improved with ozonation in advance. In sum, the integrated process removed 73% of dissolved organic carbon (DOC), 87% of UV , 77% of trihalomethane (THMs) precursors, 76% of haloacetic acid (HAAs) precursors, 83%of trichloracetic aldehyde (CH) precursor, 77% of dichloroacetonitrile (DCAN) precursor, 51% of trichloroacetonitrile (TCAN) precursor, 96% of 1,1,1-trichloroacetone (TCP) precursor and 63% of trichloronitromethane (TCNM) precursor. Hydrophobic organic matter was converted into hydrophilic organic matter during ozonation/UF, while the organic matter with molecular weight of 1000–3000 Da was remarkably decreased and converted into lower molecular weight organic matter ranged from 200–500 Da. DOC had a close linear relationship with the formation potential of DBPs.

关键词： ceramic ultrafiltration(UF) ozonation organic matter hydrophilic hydrophobic disinfection by-products

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Occurrence and removal of

Lin WANG,Yongmei LI,Xiaoling SHANG,Jing SHEN

《环境科学与工程前沿（英文）》 2014年第8卷第4期页码 519-530 doi: 10.1007/s11783-013-0610-4

摘要： Six wastewater treatment plants (WWTPs) were investigated to evaluate the occurrence and removal of -nitrosodimethylamine (NDMA), NDMA formation potential (FP) and four specific NDMA precursors, dimethylamine (DMA), trimethylamine (TMA), dimethylformamide (DMFA) and dimethylaminobenzene (DMAB). DMA and tertiary amines with DMA functional group commonly existed in municipal wastewater. Chemically enhanced primary process (CEPP) had no effect on removal of either NDMA or NDMA FP. In WWTPs with secondary treatment processes, considerable variability was observed in the removal of NDMA (19%–85%) and NDMA FP (16%–76%), moreover, there was no definite relationship between the removal of NDMA and NDMA FP. DMA was well removed in all the six surveyed WWTPs; its removal efficiency was greater than 97%. For the removal of tertiary amines, biologic treatment processes with nitrification and denitrification had better removal efficiency than conventional activated sludge process. The best removal efficiencies for TMA, DMFA and DMAB were 95%, 68% and 72%, respectively. CEPP could remove 73% of TMA, 23% of DMFA and 36% of DMAB. After UV disinfection, only 17% of NDMA was removed due to low dosage of UV was applied in WWTP. Although chlorination could reduce NDMA precursors, NDMA concentration was actually increased after chlorination.

关键词： N-nitrosodimethylamine NDMA precursors NDMA formation potential biological treatment process chemically enhanced primary process

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Precursors and potential sources of ground-level ozone in suburban Shanghai

Kun Zhang, Jialuo Xu, Qing Huang, Lei Zhou, Qingyan Fu, Yusen Duan, Guangli Xiu

《环境科学与工程前沿（英文）》 2020年第14卷第6期 doi: 10.1007/s11783-020-1271-8

摘要： Abstract • Air masses from Zhejiang Province is the major source of O3 in suburban Shanghai. • O3 formation was in VOC-sensitive regime in rural Shanghai. • O3 formation was most sensitive to propylene in rural Shanghai. A high level of ozone (O3) is frequently observed in the suburbs of Shanghai, the reason for this high level remains unclear. To obtain a detailed insight on the high level of O3 during summer in Shanghai, O3 and its precursors were measured at a suburban site in Shanghai from July 1, 2016 to July 31, 2016. Using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and concentration weighted trajectories (CWT), we found that Zhejiang province was the main potential source of O3 in suburban Shanghai. When the sampling site was controlled by south-western winds exceeding 2 m/s, the O3-rich air masses from upwind regions (such as Zhejiang province) could be transported to the suburban Shanghai. The propylene-equivalent concentration (PEC) and ozone formation potential (OFP) were further calculated for each VOC species, and the results suggested that propylene, (m+p)-xylene, and toluene played dominant roles in O3 formation. The Ozone Isopleth Plotting Research (OZIPR) model was used to reveal the impact of O3 precursors on O3 formation, and 4 base-cases were selected to adjust the model simulation. An average disparity of 18.20% was achieved between the simulated and observed O3 concentrations. The O3 isopleth diagram illustrated that O3 formation in July 2016 was in VOC-sensitive regime, although the VOC/NOx ratio was greater than 20. By introducing sensitivity (S), a sensitivity analysis was performed for O3 formation. We found that O3 formation was sensitive to propylene, (m+p)-xylene, o-xylene and toluene. The results provide theoretical support for O3 pollution treatment in Shanghai.

关键词： Ozone OZIPR Volatile organic compounds Shanghai HYSPLIT

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印度洋8.7级与8.5级地震的物理前兆

孙威,孙晓明

《中国工程科学》 2008年第10卷第2期页码 14-25

摘要：

采用自主研发的地震应力仪、谐振仪、倾斜仪和大地电位仪记录到印度洋8.7级大震的地震前兆——孕震物理模型和临震信号，印度洋8.7级地震前后和8.5级地震前后的地壳受力情况有很大差异，表明印度洋8.7级地震与8.5级地震的成因有着本质的区别，分析了海啸形成的原因，还发现了在 8.7级地震的孕育过程中有地下物质迁移迹象。

关键词：印度洋8.7级与8.5级地震临震信号顺势脉冲逆势脉冲

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A theoretical investigation on the thermal decomposition of pyridine and the effect of H

Ji Liu, Xinrui Fan, Wei Zhao, Shi-guan Yang, Wenluan Xie, Bin Hu, Qiang Lu

《化学科学与工程前沿（英文）》 2021年第15卷第5期页码 1217-1228 doi: 10.1007/s11705-020-2024-8

摘要： Pyridine is one of the main nitrogen-containing compounds in coal, and its pyrolytic mechanism to generate NO precursors (mainly NH and HCN) remains unclear. In this work, the possible pathways for the pyrolysis of pyridine to form HCN and/or NH were investigated by the density functional theory method, and the effects of H O on pyridine pyrolysis were also investigated. The results show that there are two possible reactions for the initial pyridine pyrolysis, i.e., internal hydrogen transfer and C–H bond homolysis, and that internal hydrogen transfer is more favorable. Nine possible reaction pathways following internal hydrogen transfer are obtained and analyzed. Among these pathways, pyridine prefers to produce HCN instead of NH . The existence of H O has significant effects on the decomposition of pyridine, as it participates in pyridine pyrolysis to form NH rather than HCN as the major product.

关键词： coal pyridine pyrolysis mechanism NO_x precursors DFT