Potential application of sludge produced from coal mine drainage treatment for removing Zn(II) in an aqueous phase

Various analyses of physico-chemical characteristics and batch tests were conducted with the sludge obtained from a full-scale electrolysis facility for treating coal mine drainage in order to find the applicability of sludge as a material for removing Zn(II) in an aqueous phase. The physico-chemical analysis results indicated that coal mine drainage sludge (CMDS) had a high specific surface area and also satisfied the standard of toxicity characteristic leaching procedure (TCLP) because the extracted concentrations of certain toxic elements such as Pb, Cu, As, Hg, Zn, and Ni were much less than their regulatory limits. The results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the CMDS mainly consists of goethite (70%) and calcite (30%) as a weight basis. However, the zeta potential analysis represented that the CMDS had a lower isoelectric point of pH (pH_IEP) than that of goethite or calcite. This might have been caused by the complexation of negatively charged anions, especially sulfate, which usually exists with a high concentration in coal mine drainage. The results of Fourier transform infrared (FT-IR) spectrometry analysis revealed that Zn(II) was dominantly removed as a form of precipitation by calcite, such as smithsonite [ZnCO₃] or hydrozincite [Zn₅(CO₃)₂(OH)₆]. Recycling sludge, originally a waste material, for the removal process of Zn(II), as well as other heavy metals, could be beneficial due to its high and speedy removal capability and low economic costs.     

Long-term assessment of the environmental fate of heavy metals in agricultural soil after cessation of organic waste treatments

The current study examined the anthropogenic accumulation and natural decrease in metal concentrations in agricultural soils following organic waste application. Three common organic wastes, including municipal sewage sludge, alcohol fermentation processing sludge, and pig manure compost (PMC), were applied annually to an agricultural soil under field conditions over 7 years (1994–2000) at a rate of 12.5, 25, and 50 ton ha^?1 year^?1 and the soil accumulation of three metals of concern (Cu, Pb, and Zn) was monitored. Subsequently, organic waste amendments ceased and the experimental plots were managed using conventional fertilization for another 10 years (2001–2010) and the natural decrease in metal concentrations monitored. Although Cu and Zn concentrations in all experimental plots did not exceed the relevant guideline values (150 mg kg^?1 for Cu and 300 mg kg^?1 for Zn), significant increases in metal concentrations were observed from cumulative application of organic wastes over 7 years. For instance, PMC treatment resulted in an increase in Cu and Zn from 9.8 and 72 mg kg^?1 to 108.2 and 214.3 mg kg^?1, respectively. In addition, the natural decrease in Cu and Zn was not significant as soils amended with PMC showed only a 16 and 19 % decline in Cu and Zn concentrations, respectively, even 10 years after amendment ceased. This research suggested that more attention must be paid during production of organic waste-based amendments and at the application stage.     

Application of powdered activated carbon coating to fabrics in a hybrid filter to enhance mercury removal

Elemental mercury(Hg0) is predominant constituent of flue gas emitted from coal-fired power plants. Adsorption has been considered the best available technology for removal of Hg0 from flue gas. However, adsorbent injection increases the amount of ash generated. In the present study, powdered activated carbon(PAC) was coated on polytetrafluoroethylene/glass fiber filters to increase Hg0 removal while concurrently reducing the amount of ash generated. The optimal PAC coating rate was determined in laboratory experiments to ensure better Hg0 removal with low pressure drop. When PAC of particle size less than 45 μm was used, and the areal density was 50 g/m2, the pressure drop remained under 30 Pa while the Hg0 removal efficiency increased to 15.8% from4.3%. The Hg0 removal efficiency also increased with decrease in filtration velocity. The optimal PAC coating rate was applied on a hybrid filter(HF), which was combined with a bag filter and an electrostatic precipitator in a single chamber. Originally designed to remove fine particulates matter, it was retrofitted to the flue gas control device for simultaneous Hg0 removal. By employing the PAC coating, the Hg removal efficiency of the HF increased to 79.79% from 66.35%. Also, a temporary reduction in Hg removal was seen but this was resolved following a cleaning cycle in which the dust layer was removed.     

典型城市臭氧污染源贡献及控制策略费效评估

东莞是珠三角O_3污染最严重的城市,使用RSM/CMAQ(曲面响应模型)法分析了珠三角区域人为排放的NO_x和VOCs对东莞市O_3浓度变化源贡献.2014基准年分析结果表明,扣除模型域外区域传输及天然源排放对O_3本底浓度贡献(41.00%)后,东莞本地VOCs排放对O_3贡献最大(18.50%),珠三角区域NO_x减排率13%时可持续降低东莞市O_3浓度.进一步使用ABa CAS-SE(空气污染控制成本效益与达标评估系统)对2017、2020、2025东莞市3个未来年O_3污染控制情景进行了费效评估.评估结果显示,NO_x和VOCs控制比例相对较低的2017年控制情景人体健康效益/区域控制成本比约为1.1;而控制比例相对较高的2025年东莞O_3达标情景效益成本比仅为0.1.这说明,在高减排率情景下,以末端治理为主的控制措施经济可行性较差,需综合采取产业/能源结构调整、清洁生产等措施实现NO_x和VOCs的大比例减排,实现东莞O_3的稳定达标.今后将进一步研究NO_x和VOCs减排对PM_(2.5)环境浓度及健康效益影响,开展多目标污染物协同控制费效评估.     

长江三角洲地区大气O3和PM10的区域污染特征模拟

以TRACE-P污染源资料及上海市地方排放清单为基础,采用Models-3/CMAQ环境空气质量模型和中尺度气象模式MM5,模拟研究了2001-01和2001-07长三角近地面二次污染物O3及PM 10的浓度分布及输送状况,并以上海市国控点2001年冬、夏季各10 d的小时监测数据对模型进行了验证.验证结果显示,Models-3/CMAQ对O3和PM10的模拟结果与监测值的相关系数分别为0.77和0.52;一致性指数分别达到0.81和0.99.模型对O3小时最高浓度的估算偏低27%,标准偏差为-3.1%;对PM10小时平均浓度的估算偏低10%,标准偏差为46%.模型已具备再现和模拟长三角大气污染输送过程的能力,且误差落在可接受的范围之内.模拟结果显示,2001-07长三角区域16个主要城市中,有14个城市O3小时最大浓度超过国家二级标准,高浓度O3可覆盖苏南和浙北广大区域.2001-01泰州、扬州、南京、镇江、常州等城市受本地排放源和北部大气污染输送的影响显著,大气PM10日均浓度超过PM10国家二级标准.长三角地区环境空气质量与污染类型受大气污染传输与化学转化的影响十分明显.夏季太阳辐射较强时,南部城市排放的污染物常以二次污染物的形式影响下风向城市;太阳辐射较弱的情况下,则以一次污染物输送为主的形式影响周边地区.冬季长三角区域颗粒物污染总体水平较高,这与我国北方地区排放的颗粒物在西北风作用下向长三角输送造成的影响密切相关.长三角地区的大气污染已逐渐从局地转为区域问题.     

大气汞污染模拟研究进展及控制策略优化方法

简评了国内外大气汞污染模拟相关研究情况,指出目前我国大气汞排放模拟及污染控制研究工作非常缺乏,严重影响了我国汞污染控制策略制定以及"汞环境外交纠纷"的积极应对;并据此建议应该对我国大气汞污染模拟及控制策略优化进行系统研究,其研究内容包括:汞排放清单的建立、大气汞的长程输送、响应面模型软件(response surfac...     

应用Models-3/CMAQ研究长三角区域大气污染及输送

选用美国国家环保局第3代空气质量模式（Models-3，／CMAQ），配合中尺度气象模式（MM5）进行研究，模拟了2001年1、7月份长江三角洲区域冬夏季典型天气条件下大气层二次污染物臭氧及颗粒物的浓度分布及输送状况。采用2001年冬．夏季各10d的小时监测数据对模式验证。结果表明，Models-3／CMAQ对O3、PM10的模拟相关系数分别为0．77和052；一致性指数分别达到081和0．99。模型对于O3略微低估，标准偏差为-31％，而对于PM10则有所高估，标准偏差为46％。对长三角7月份O3浓度及1月份PM10的模拟结果显示，7月份长三角区域16个主要城市O3日均浓度集中在0．043～0．086mg／m^3之间，其中，泰州、扬州．湖州、镇江O3月日均浓度相对较高，均超过0．064mg／m3o模拟时段内O3最高小时浓度达0．276mg／m^3。1月份整个模拟区域PM10月日均浓度为O056mg／m^3，其中，南京市PM10日均浓度最高，达0．080mg／m^3模拟时段内PM10最高小时浓度达0.432mg／m^3研究表明，长三角地区存在明显的污染物输送现象，大气污染已经从局地污染转化为区域污染。     

Separation of PCBs and PAHs in sediment samples using silica gel fractionation chromatography

The aim of this research is to develop a silica gel fractionation procedure for sediment sample extracts, which separates polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) into two groups, while simultaneously eliminating most interfering substances for subsequent instrumental analysis. This is achieved by optimizing the fraction cut-off volume of eluting solvent and the deactivation level of the silica gel. Using fully activated silica gel and cutting off PCB collection after passing 60-65 ml eluting solvent (pentane or hexane) through the column resulted in satisfactory separation of PCBs and PAHs. This procedure tends to have a higher reliability for PCBs and PAHs with higher molecular mass. This approach deviates only slightly from the standard methods of the USEPA, and it is less expensive due to reduced sample pre-treatment time and solvent consumption.     

Monitoring of environmental contaminants in raw bovine milk and estimates of dietary intakes of children in South Korea

Persistent organic pollutants (POPs) are ubiquitous residual contaminants in the environment and in the food chain. Milk is an important matrix for monitoring POP contamination. This study determined the concentrations of POPs including polybrominated diphenyl ethers (PBDEs), hexachlorobenzene (HCB), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (DL-PCBs) in raw bovine milk, and the data was used to estimate dietary intakes in South Korea. The average concentrations of PBDEs, HCB, PCDD/Fs, and DL-PCBs in raw milk were 0.29 ng g⁻¹ fat, 0.50 ng g⁻¹ fat, 0.27 pg TEQ g⁻¹ fat, and 0.33 pg TEQ g⁻¹ fat, respectively. No significant relationship was found between the concentrations of analytes and the regions sampled. The dietary intakes of PBDEs from the consumption of milk was calculated to be 0.26, 0.10, and 0.05 ng kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. The dietary intakes of HCB was calculated to be 0.44, 0.16, and 0.09 ng kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. The dietary intakes of PCDD/Fs and DL-PCBs was calculated to be 0.78, 0.29, and 0.16 pg TEQ kg⁻¹ bw d⁻¹ for the group of ages 0–6, 7–12, and 13–19, respectively. These results indicated that the residual levels of PBDEs, HCB, PCDD/Fs, and DL-PCBs in raw bovine milk were within safe levels.