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621.
622.
介绍了气体检测报警器中催化燃烧式、红外式、电化学式、光电离式传感器的工作原理,提出了不同气体检测报警器使用中的注意事项。 相似文献
623.
Membrane fouling limits the effects of long-term stable operation of membrane bioreactor (MBR). Control of membrane fouling can extend the membrane life and reduce water treatment cost effectively. A pilot scale anoxic/aerobic-membrane bioreactor (A/O-MBR, 40 L/hr) was used to treat the hyperhaline municipal sewage from a processing zone of Tianjin, China. Impact factors including mixed liquid sludge suspension (MLSS), sludge viscosity (μup), microorganisms, extracellular polymeric substances (EPS), aeration intensity and suction/suspended time on membrane fouling and pollution control were studied. The relationships among various factors associated with membrane fouling were analyzed. Results showed that there was a positive correlation among MLSS, sludge viscosity and trans-membrane pressure (TMP). Considering water treatment efficiency and stable operation of the membrane module, MLSS of 5 g/L was suggested for the process. There was a same trend among EPS, sludge viscosity and TMP. Numbers and species of microorganisms affected membrane fouling. Either too high or too low aeration intensity was not conducive to membrane fouling control. Aeration intensity of 1.0 m3/hr (gas/water ratio of 25:1) is suggested for the process. A long suction time caused a rapid increase in membrane resistance. However, long suspended time cannot prevent the increase of membrane resistance effectively even though a suspended time was necessary for scale off particles from the membrane surface. The suction/suspended time of 12 min/3 min was selected for the process. The interaction of various environmental factors and operation conditions must be considered synthetically. 相似文献
624.
Hong Zhao Yunshan Ge Jianwei Tan Hang Yin Jiadong Guo Wei Zhao Peipei Dai 《环境科学学报(英文版)》2011,23(11):1831-1838
The effects of different mixing ratios of methanol/gasoline blends and new three-way catalytic converter on regulated and unregulated emissions, especially VOC and carbonyl compound emissions were investigated. 相似文献
625.
Association of serum concentration of organochlorine pesticides with dietary intake and other lifestyle factors among urban Chinese women 总被引:1,自引:0,他引:1
Lee SA Dai Q Zheng W Gao YT Blair A Tessari JD Tian Ji B Shu XO 《Environment international》2007,33(2):157-163
Concerns about the carcinogenic and endocrine-disrupting characteristics of organochlorine pesticides (OCPs) have led to a global ban on OCP use. However, OCPs persist in the environment for decades because of their long half-life. We evaluated serum levels of OCPs and their correlations with usual dietary intake and other lifestyle factors among 250 healthy women who participated as controls in the Shanghai Breast Cancer Study. Serum levels of hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH), dichloro-di-phenyl-trichloroethane (DDT) isomers (p,p'-DDE and p,p'-DDT), hexachlorobenzene (HCB), trans-nonachlor (TNC), and eight polychlorinated biphenyls (PCB) congeners (IUPAC no. 74, 118, 138, 153, 170, 180, 183, and 187) were measured. Lifestyle factors and usual dietary habits over the past 5 years were assessed through an in-person interview. With the exception of PCB, total OCP levels in our study population were significantly higher than those observed in other countries. Age, income, body mass index, waist-to-hip ratio, number of pregnancies, and/or total duration of breastfeeding were all significantly correlated with all types of OCPs. Of the 20 food groups evaluated, correlations with serum total OCPs were observed for eggs (r=0.13), fresh beans (r=-0.17), tea (r=0.14), and animal fat (r=0.18). Multiple regression analyses showed that age and animal fat intake were positively associated with serum total level OCPs, while leafy vegetable and fresh bean consumption was negatively associated with OCPs level. Our study suggests that dietary intake may be an important contributor of serum levels of OCPs in Chinese women. 相似文献
626.
含硫底物种类与浓度对污泥重金属生物沥滤的影响 总被引:1,自引:0,他引:1
以城市污水处理厂剩余污泥为材料,探究不同含硫底物及其浓度对污泥重金属生物沥滤的效果影响,通过添加单一底物(S0、Fe SO4、Na2S2O3、Fe S和Fe S2)、两种底物配合(S0+Fe SO4、S0+Na2S2O3、S0+Fe S、S0+Fe S2)进行沥滤实验。结果表明:除Fe S和Fe S2外,投加单一底物的沥滤体系中p H都呈下降趋势,沥滤持续5 d后p H值降至1.8左右,污泥中Zn、Pb、Ni、Cr和Cu等重金属去除率高,底物投加量为8~10 g/L(以S计);投加复合底物时,最佳投加方式为S0+Fe SO4,投加量为8 g/L,此时污泥体系酸化速度快,污泥中重金属Zn、Pb、Ni、Cr、Cu去除率分别达95.41%、89.48%、86.45%、84.51%和94.33%。 相似文献
627.
628.
To evaluate contamination caused by petroleum, surface soil samples were collected from both upland and paddy fields along the irrigation canals in the Hunpu wastewater irrigation region in northeast China. N-alkanes, terpanes, steranes, and phospholipid fatty acids (PLFA) in the surface soil samples were analyzed. The aliphatic hydrocarbon concentration was highest in the samples obtained from the upland field near an operational oil well; it was lowest at I-3P where wastewater irrigation promoted the downward movement of hydrocarbons. The Hunpu region was found contaminated by heavy petroleum from oxic lacustrine fresh water or marine deltaic source rocks. Geochemical parameters also indicated significantly heavier contamination and degradation in the upland fields compared with the paddy fields. Principal component analysis based on PLFA showed various microbial communities between petroleum contaminated upland and paddy fields. Gram-negative bacteria indicated by 15:0, 3OH 12:0, and 16:1(9) were significantly higher in the paddy fields, whereas Gram-positive bacteria indicated by i16:0 and 18:1(9)c were significantly higher in the upland fields (p < 0.05). These PLFAs were related to petroleum contamination. Poly-unsaturated PLFA (18:2ωup6, 9; indicative of hydrocarbon-degrading bacteria and fungi) was also significantly elevated in the upland fields. This paper recommends more sensitive indicators of contamination and degradation of petroleum in soil. The results also provide guidelines on soil pollution control and remediation in the Hunpu region and other similar regions. 相似文献
629.
Chien-Chung Chen Tzu-Chi Wang Lu-Yen Chen Jie-Huei Dai Chi-Min Shu 《Journal of Loss Prevention in the Process Industries》2010,23(4):531-538
Industrial safety has noticeably improved in recent years in Taiwan. Despite these improvements, however, serious accidents including explosions, chemical releases, and fires have still occurred in companies such as the Fu Guo Chemical Company (2001), Sin Hun Chemical Company (2005), Motech Industries, Inc. (2005) and Nanpao Resin Co. (2010). These accidents resulted in great loss of life and property, and further caused demands for improvement. Chemical disasters usually result from the combination of several mistakes or gross carelessness and are seldom caused by a single episode. To ensure the safety of operating, handling and storing chemicals, as well as to prevent chemical disasters, one must take many critical points into account, such as techniques, manufacturing processes, operators, chemicals, and emergency response. In Taiwan, the hazards and risks of high-tech companies are higher than in other industrial sectors. Therefore, a variety of safety management methods and regulations appropriate for high-tech companies have been generated. We studied the current status of the indigenous loss prevention protocols based on the safety management of petrochemical and chemical-process high-tech industries in Taiwan. 相似文献
630.