Advanced treatment of biologically pretreated coal gasification wastewater by a novel heterogeneous Fenton oxidation process

Sewage sludge from a biological wastewater treatment plant was converted into sewage sludge based activated carbon(SBAC) with Zn Cl2 as activation agent, which was used as a support for ferric oxides to form a catalyst(Fe Ox/SBAC) by a simple impregnation method.The new material was then used to improve the performance of Fenton oxidation of real biologically pretreated coal gasification wastewater(CGW). The results indicated that the prepared Fe Ox/SBAC significantly enhanced the pollutant removal performance in the Fenton process, so that the treated wastewater was more biodegradable and less toxic. The best performance was obtained over a wide p H range from 2 to 7, temperature 30°C, 15 mg/L of H2O2 and 1 g/L of catalyst, and the treated effluent concentrations of COD, total phenols,BOD5 and TOC all met the discharge limits in China. Meanwhile, on the basis of significant inhibition by a radical scavenger in the heterogeneous Fenton process as well as the evolution of FT-IR spectra of pollutant-saturated Fe Ox/BAC with and without H2O2, it was deduced that the catalytic activity was responsible for generating hydroxyl radicals, and a possible reaction pathway and interface mechanism were proposed. Moreover, Fe Ox/SBAC showed superior stability over five successive oxidation runs. Thus, heterogeneous Fenton oxidation of biologically pretreated CGW by Fe Ox/SBAC, with the advantages of being economical, efficient and sustainable, holds promise for engineering application.     

罗布泊“大耳朵”地区沉积物重金属含量及空间分布特征

以罗布泊"大耳朵"地区为研究区域,利用石墨炉原子吸收分光光度计(GF-990)和火焰原子吸收分光光度计(AAS-990)分析测试了沉积物中Pb、Cu、Ni和Mn元素的总量,并测定了沉积物中有机质的含量,运用SPSS软件分析了各重金属总量与有机质之间的相互关系。结果表明:罗布泊"大耳朵"地区盐壳层沉积物中Pb含量的变化范围在2.57~58.63 mg/kg,Cu含量的变化范围在6.33~39.65 mg/kg,Ni含量的变化范围在5.55~46.33 mg/kg,Mn含量的变化范围在46.33~1474.60 mg/kg;除Pb的垂直分布随着深度的增加其含量减少并趋于稳定外,重金属Cu、Ni和Mn的总量在各剖面垂直方向上大部分呈波折多峰行分布,分布趋势差异较大;重金属Pb、Cu、Ni和Mn与有机质都存在显著相关性。     

Development and case study of a science-based software platform to support policy making on air quality

This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, uses a response surface modeling (RSM) methodology and serves as a visualization and analysis tool (VAT) for three-dimensional air quality data obtained by atmospheric models. The software features a number of powerful and intuitive data visualization functions for illustrating the complex nonlinear relationship between emission reductions and air quality benefits. The case study of contiguous U.S. demonstrates that the enhanced RSM-VAT is capable of reproducing the air quality model results with Normalized Mean Bias < 2% and assisting in air quality policy making in near real time.     

Nitrogen removal from coal gasification wastewater by activated carbon technologies combined with short-cut nitrogen removal process

A system combining granular activated carbon and powdered activated carbon technologies along with shortcut biological nitrogen removal （GAC-PACT-SBNR） was developed to enhance total nitrogen （TN） removal for anaerobically treated coal gasification wastewater with less need for external carbon resources. The TN removal efficiency in SBNR was significantly improved by introducing the effluent from the GAC process into SBNR during the anoxic stage, with removal percentage increasing from 43.8%49.6% to 68.8%-75.8%. However, the TN removal rate decreased with the progressive deterioration of GAC adsorption. After adding activated sludge to the GAG compartment, the granular carbon had a longer service-life and the demand for external carbon resources became lower. Eventually, the TN removal rate in SBNR was almost constant at approx. 43.3%, as compared to approx. 20.0% before seeding with sludge. In addition, the production of some alkalinity during the denitrification resulted in a net savings in alkalinity requirements for the nitrification reaction and refractory chemical oxygen demand （COD） degradation by autotrophic bacteria in SBNR under oxic conditions. PACT showed excellent resilience to increasing organic loadings. The microbial community analysis revealed that the PACT had a greater variety of bacterial taxons and the dominant species associated with the three compartments were in good agreement with the removal of typical pollutants. The study demonstrated that pre-adsorption by the GAC-sludge process could be a technically and economically feasible method to enhance TN removal in coal gasification wastewater （CGW）.     

Removal of formaldehyde over MnxCe1-xO2 catalysts: Thermal catalytic oxidation versus ozone catalytic oxidation

MnxCe1- xO2（x： 0.3–0.9） prepared by Pechini method was used as a catalyst for the thermal catalytic oxidation of formaldehyde（HCHO）. At x = 0.3 and 0.5, most of the manganese was incorporated in the fluorite structure of Ce O2 to form a solid solution. The catalytic activity was best at x = 0.5, at which the temperature of 100% removal rate is the lowest（270°C）. The temperature for 100% removal of HCHO oxidation is reduced by approximately 40°C by loading 5 wt.% Cu Oxinto Mn0.5Ce0.5O2. With ozone catalytic oxidation, HCHO（61 ppm） in gas stream was completely oxidized by adding 506 ppm O3 over Mn0.5Ce0.5O2 catalyst with a GHSV（gas hourly space velocity） of 10,000 hr-1at 25°C. The effect of the molar ratio of O3 to HCHO was also investigated. As O3/HCHO ratio was increased from 3 to 8, the removal efficiency of HCHO was increased from 83.3% to 100%. With O3/HCHO ratio of 8, the mineralization efficiency of HCHO to CO2 was 86.1%. At 25°C, the p-type oxide semiconductor（Mn0.5Ce0.5O2） exhibited an excellent ozone decomposition efficiency of 99.2%,which significantly exceeded that of n-type oxide semiconductors such as Ti O2, which had a low ozone decomposition efficiency（9.81%）. At a GHSV of 10,000 hr-1, [O3]/[HCHO] = 3 and temperature of 25°C, a high HCHO removal efficiency（≥ 81.2%） was maintained throughout the durability test of 80 hr, indicating the long-term stability of the catalyst for HCHO removal.     

Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

Estuarine wetland, where freshwater mixes with salt water, comprises different regions（rivers and marine ecosystems） with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration（SR）. ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration（SMR） of the tidal wetland with lower salinity（JS） were significantly higher than those of the tidal wetland with higher salinity（ZXS）（p 〈 0.05）. However, unlike SMR and SR, the difference in the soil microbial biomass（SMB） was not significant（p 〉 0.05）with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.     

中国木质林产品碳足迹的产业链分布特征分析

中国是木质林产品的生产、消费和出口大国,分析其产品碳足迹的分布特征对于林产行业的国际贸易和节能减排工作具有重要意义。文章采用投入产出生命周期模型计算中国木质林产品的碳足迹,并对不同种类木质林产品产业链上的碳足迹分布进行分析。研究结果表明,产品碳足迹总量最大的木质林产品是木家具(占总量的36%),而单位产品碳足迹强度最大的木质林产品是纸制品(占整体的16%);针对林产品行业内部的产业链角度,碳足迹的主要流量发生在从用材林的种植和养护业到最终产品的制造;林产品产业行业外部,碳足迹的贡献则主要来自于金属冶炼及压延加工业、化石燃料开采业等行业,这2个行业碳足迹贡献分别占21%和18%;整体上,中国木质林产品生产中温室气体的排放以燃料燃烧产生的二氧化碳为主,这与产业链外其他行业的碳贡献密不可分。研究表明,通过碳足迹在产业链上的分布可以有助于分析林产品碳排放的工作重心。     

四种环境雌激素对斑马鱼内脏团抗氧化防御系统的影响研究——17B-雌二醇与三种增塑剂DMP、DBP、DOP的影响

以斑马鱼(Danio rerio)为受试动物,研究了四种环境雌激素-17β-雌二醇(E2)和三种增塑剂(DMP、DBP、DOP)对其内脏团的氧化损伤及应激效应。经急性毒性实验,得到E2、DMP、DBP、DOP对成体斑马鱼96 h的半数致死浓度(LC50)分别为2.51、12.33、9.67、9.89 mg·L-1。在此基础上分别设置5个浓度梯度,研究E2(暴露2 d,4 d)、DMP、DBP、DOP(暴露4 d)对斑马鱼内脏团的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽硫转移酶(GST)活性以及丙二醛(MDA)含量的影响。结果表明,SOD、CAT、GST、MDA对这四种环境激素都非常敏感,其中SOD、CAT、GST活性的影响均呈现先诱导后抑制的趋势,而MDA含量则随着污染物浓度的升高而增加。高浓度暴露条件下,E2(0.4 mg·L-1)和DMP、DBP、DOP(0.8 mg·L-1)对SOD、CAT、GST活性均有显著抑制(p0.05),MDA的含量有显著升高(p0.05)。可见,E2、DMP、DBP、DOP会导致斑马鱼内脏团氧化损伤,并且在同等浓度下E2的毒性明显高于三种增塑剂。     

Quantifying the human health benefits of curbing air pollution in Shanghai

Urban development in the mega-cities of Asia has caused detrimental effects on the human health of its inhabitants through air pollution. However, averting these health damages by investing in clean energy and industrial technologies and measures can be expensive. Many cities do not have the capital to make such investments or may prefer to invest that capital elsewhere. In this article, we examine the city of Shanghai, China, and perform an illustrative cost/benefit analysis of air pollution control. Between 1995 and 2020 we expect that Shanghai will continue to grow rapidly. Increased demands for energy will cause increased use of fossil fuels and increased emissions of air pollutants. In this work, we examine emissions of particles smaller than 10 microm in diameter (PM10), which have been associated with inhalation health effects. We hypothesize the establishment of a new technology strategy for coal-fired power generation after 2010 and a new industrial coal-use policy. The health benefits of pollution reduction are compared with the investment costs for the new strategies. The study shows that the benefit-to-cost ratio is in the range of 1-5 for the power-sector initiative and 2-15 for the industrial-sector initiative. Thus, there appear to be considerable net benefits for these strategies, which could be very large depending on the valuation of health effects in China today and in the future. This study therefore provides economic grounds for supporting investments in air pollution control in developing cities like Shanghai.