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361.
Effects of chlortetracycline, Cu and their combination on the performance and microbial community dynamics in swine manure anaerobic digestion 总被引:1,自引:0,他引:1
Rui Wang Junya Zhang Jibao Liu Dawei Yu Hui Zhong Yawei Wang Meixue Chen Juan Tong Yuansong Wei 《环境科学学报(英文版)》2018,30(5):206-215
Swine manure was typical for the combined pollution of heavy metals and antibiotics. The effects of widely used veterinary antibiotic chlortetracycline(CTC), Cu and their combination on swine manure anaerobic digestion performance and microbial community have never been investigated. Thus, four 2 L anaerobic digestion reactors were established including reactor A(control), B(CTC spiked by 0.5 g/kg dry weight, dw), C(Cu spiked by 5 g/kg dw) and D(combination of CTC, 0.5 g/kg dw, and Cu, 5 g/kg dw), and dynamics of bacterial and archaeal community structure was investigated using high throughput sequencing method. Results showed that addition of CTC and Cu separately could increase the total biogas production by21.6% and 15.8%, respectively, while combination of CTC and Cu severely inhibited anaerobic digestion(by 30.3%). Furthermore, corresponding to different stages and reactors, four kinds of microbes including bacteria and archaea were described in detail, and the effects of CTC, Cu and their combination mainly occurred at hydrolysis and acidification phases. The addition of Cu alone changed the dynamics of archaeal community significantly. It was genus Methanomassiliicoccus that dominated at the active methane production for A, B and D, while it was genus Methanobrevibacter and Methanoculleus for C. 相似文献
362.
着眼于辽宁省经济发展与环境问题凸显的现状,基于压力-状态-响应(P-S-R)生态安全评价模型,选取辽宁省14个城市2003年-2012年的经济、社会与环境等25个指标数据进行生态安全综合评价,对生态安全演变趋势进行分析.结果表明:十年来辽宁省城市生态安全指数呈现整体上升趋势,生态安全综合评价指数基本与生态安全指数变化趋势相似,说明辽宁省生态安全状况正逐步改善,并且总体呈现发展趋势,辽宁省的生态安全建设取得一定进展. 相似文献
363.
364.
Electro-Fenton degradation of cationic red X-GRL using an activated carbon fiber cathode 总被引:1,自引:0,他引:1
Hengyi Lei Hualiang Li Zhong Li Zhaoxu Li Kai Chen Xinghong Zhang Huiqin Wang 《Process Safety and Environmental Protection》2010,88(6):431-438
We reported the study of the degradation of the azo dye cationic red X-GRL by the electro-Fenton process using an activated carbon fiber cathode. The electrogeneration of hydrogen peroxide in solution using different material cathodes fed with air was investigated, and the results revealed that the activated carbon fiber cathode was more effective compared to the graphite cathode. The decolorization and mineralization of cationic red X-GRL were also determined. The effect of the operating parameters, such as the initial Fe2+ concentration, temperature and initial dye concentration, was investigated. The optimum Fe2+ catalyst concentration values for the degradation of cationic red X-GRL was found to be 5 mM. The rate of decolorization and mineralization of dye could be accelerated by increasing the temperature. In addition, the decolorization and total organic carbon (TOC) removal efficiency decreased with the increasing initial dye concentration, while the TOC removal increased. Two different transition metal ions (Cu2+ and Mn2+) were applied as substitutes for ferrous sulfate for evaluating catalytic effect. The results indicated that Cu2+ and Mn2+ were more effective than Fe2+ in catalyzing the degradation of the dye. 相似文献
365.
366.
Some characteristics of crowd jam like the phenomena of discontinuous jumping in reality are hard to be explained by the equations governing pedestrians. The catastrophe theory can explain these characteristics. A cusp-catastrophe model is developed to analyze the mechanics of crowd jam by drawing graphs for a cusp-catastrophe model of crowd, the bifurcation set and the projection of catastrophe model. Meanwhile, the critical density and the critical velocity are derived. It is concluded that the cusp model is a more efficient predictor than the linear model or the equations governing pedestrians and is reasonably realistic for dense crowd flow scenarios. 相似文献
367.
Globally, many commercial bivalve populations have declined in recent decades. In addition to overharvesting and habitat loss,
the increasing frequency and intensity of harmful algal blooms (HABs) are likely to contribute to bivalve losses, particularly
in cases where blooms negatively impact larval stages. This paper reports on the lethal effects of clonal cultures and blooms
of Cochlodinium polykrikoides from the US Atlantic coast on the larvae of three species of commercially and ecologically valuable bivalves: the Eastern
oyster (Crassostrea virginica), the bay scallop (Argopecten irradians), and the Northern quahog (hard clam; Mercenaria mercenaria). Both cultures and blooms of C. polykrikoides were highly toxic to all three species of bivalve larvae causing 80–100% mortality during 24- to 72-h exposures at concentrations
of 1–2 × 103 cells ml−1. Toxicity was dependent on cell densities, growth stage of C. polykrikoides (i.e. cultures in exponential stage growth were more toxic than later stages), exposure time of larvae to cells (i.e. longer
exposure caused higher mortality), the age of larvae (i.e. younger larvae were more sensitive), and the relative abundance
of C. polykrikoides (i.e. the presence of other microalgae decreased toxicity). Free radical-scavenging enzymes (peroxidase and catalase) and
the removal of C. polykrikoides cells (i.e. culture filtrate) significantly increased larval survival suggesting toxicity is maximized by contact with live
cells and may involve labile toxins bound by these compounds including e.g. reactive oxygen species. The toxicity of C. polykrikoides to bivalve larvae was generally more severe than other HAB species (e.g. Karenia brevis, Karlodinium veneficum, Alexandrium tamarense, Prorocentrum minimum). Since the bivalves in this study spawn in the months when C. polykrikoides blooms on the east coast of North America, these results suggest that these blooms may have detrimental effects on efforts
to restore these already diminished populations. 相似文献
368.
Jingqiu Mao Xinrong Ren Shuang Chen William H. Brune Zhong Chen Monica Martinez Hartwig Harder Barry Lefer Bernhard Rappenglück James Flynn Michael Leuchner 《Atmospheric environment (Oxford, England : 1994)》2010,44(33):4107-4115
Both similarities and differences in summertime atmospheric photochemical oxidation appear in the comparison of four field studies: TEXAQS2000 (Houston, 2000), NYC2001 (New York City, 2001), MCMA2003 (Mexico City, 2003), and TRAMP2006 (Houston, 2006). The compared photochemical indicators are OH and HO2 abundances, OH reactivity (the inverse of the OH lifetime), HOx budget, OH chain length (ratio of OH cycling to OH loss), calculated ozone production, and ozone sensitivity. In terms of photochemical activity, Houston is much more like Mexico City than New York City. These relationships result from the ratio of volatile organic compounds (VOCs) to nitrogen oxides (NOx), which are comparable in Houston and Mexico City, but much lower in New York City. Compared to New York City, Houston and Mexico City also have higher levels of OH and HO2, longer OH chain lengths, a smaller contribution of reactions with NOx to the OH reactivity, and NOx-sensitivity for ozone production during the day. In all four studies, the photolysis of nitrous acid (HONO) and formaldehyde (HCHO) are significant, if not dominant, HOx sources. A problematic result in all four studies is the greater OH production than OH loss during morning rush hour, even though OH production and loss are expected to always be in balance because of the short OH lifetime. The cause of this discrepancy is not understood, but may be related to the under-predicted HO2 in high NOx conditions, which could have implications for ozone production. Three photochemical indicators show particularly high photochemical activity in Houston during the TRAMP2006 study: the long portion of the day for which ozone production was NOx-sensitive, the calculated ozone production rate that was second only to Mexico City's, and the OH chain length that was twice that of any other location. These results on photochemical activity provide additional support for regulatory actions to reduce reactive VOCs in Houston in order to reduce ozone and other pollutants. 相似文献
369.
聚合氯化铝铁处理工业废水的试验研究 总被引:10,自引:2,他引:10
采用PAFC分别处理造纸和印染两种工业废水,优化各种絮凝条件,如投药量、pH值、搅拌强度和搅拌时间等,并与PAC和PFS的絮凝效果进行比较。结果表明,PAFC在用量和浊度去除率方面并没有明显的优势,但其COD去除率(82.53%,90.58%)明显高于PAC和PFS,经PAFC处理后的印染废水达到国家一级标准,造纸中段废水也接近了国家二级标准。 相似文献
370.
采用反硝化-沸石曝气生物滤池(ZBAF)部分亚硝化及氧氨氧化组合工艺处理老龄垃圾渗滤液,探究ZBAF部分亚硝化特性以及组合工艺的脱氮除碳性能.结果表明通过游离氨(FA)对亚硝酸盐氧化菌(NOB)的选择性抑制ZBAF可以实现老龄垃圾渗滤液稳定高效部分亚硝化,平均亚硝氮积累率(NAR)为93.8%亚硝氮产率(NPR)最高达1.659 kg·(m3·d-1;在进水中投加葡萄糖700mg·L-1后,当回流比为2.0 HRT为2.2 d时,由于反硝化与厌氧氨氧化的协同作用,组合工艺脱氮效果最佳,平均氨氮去除率(ARE)、总氮去除率(NRE)和总氮去除负荷(NRR)分别达97.2%、90.0%和0.585 kg·(m3·d)-1,平均COD去除率为45.3%其中厌氧氨氧化平均NRRANA为1.060 kg·(m3·d)-1最高达1.268 kg·(m3·d)-1.利用高通量测序技术... 相似文献