分步沉淀法处理酸性矿山废水

采用分步沉淀工艺处理酸性矿山废水,考察了工艺条件对废水中有价金属元素回收效果的影响。实验结果表明:Ca(OH)_2为适宜的废水pH调节剂;调节废水pH至4.00左右并投加0.05 mL/L的H_2O_2,可首先去除Fe~(2+)及Fe~(3+),得到富Fe渣(w(Fe)=51.00%);调节废水pH至6.00~6.50,先投加50 mg/L的Na_2S,去除废水中的Cu~(2+),获得富Cu渣(w(Cu)=10.89%),再将Na_2S的投加量增至100 mg/L,去除废水中的Zn与Mn,获得富Zn-Mn渣(w(Cu)=2.37%,w(Mn)=6.79%,w(Pb)=1.61%);进一步调节废水pH至8.40,可去除剩余的Zn、Mn及其他重金属。分步沉淀工艺处理后的废水可达标排放,产生的富Fe渣、富Cu渣及富Zn-Mn渣可直接出售或具有利用价值。分步沉淀工艺可实现有价金属元素的高效回收,大幅度降低废水处理的实际成本,值得工程应用与推广。     

安徽某铁矿酸性矿山废水夏季和秋季微生物群落结构特征

分别采集了夏秋两季安徽某铁矿的酸性矿山废水样品,分析其物理化学参数,并利用分子生物学方法研究了该酸性矿山废水中微生物群落结构随时间和空间的变化规律.结果表明:该矿山废水酸性极强,夏季所采样品pH在2.80左右,且阴阳离子含量很高,Al~(3+)为1108~1138mg·L~(-1),SO_4~(2-)则高达19.80~23.79 g·L~(-1).秋季样品p H没有明显变化,但由于两次采样期间的大量降水,样品中各离子含量明显低于夏季.值得注意的是,该极端酸性的矿山废水中叶绿素a含量较高,夏季达63.8~94.2μg·L~(-1),秋季则降至16.6~32.7μg·L~(-1).无论是在夏季还是秋季,Alphaproteobacteria在绝大多数位点的细菌群落中占据着优势地位.化能异养菌Acidiphilium是最主要的细菌菌属,它在夏季和秋季各位点群落中所占比例都达20%左右,这应该与其丰富的代谢方式有关.对于真核微生物群落,夏季主要为尖毛虫和小球藻,秋季主要为棕鞭藻和小球藻.小球藻是该酸性生态系统主要的生产者,尖毛虫和棕鞭藻则扮演着顶级消费者的角色.该酸性废水应处于酸水形成末期,所以细菌群落中化能异养菌占据着优势地位,化能自养菌比例较少.由于温度等理化性质的不同,微生物群落结构随时间和空间发生了一定变化,其中以真核微生物群落结构变化最为显著.     

Gas explosion analysis of safety gap effect on the innovating FLNG vessel with a cylindrical platform

After investigating gas dispersion on a cylindrical Floating Liquefied Natural Gas (FLNG) platform (Li et al, 2016), this second article focuses on assessment of gas explosion by using Computational Fluid Dynamics (CFD). Gas explosion simulations are carried out to evaluate the explosion overpressure mitigating effect of safety gap. The Data-dump technique, which is an effective tool in resetting turbulence length scale in gas explosion overpressure calculation, is applied to ensure simulation accuracy for the congestion scenario with safety gap. Two sets of different safety gaps are designed to investigate the safety gap on the cylindrical FLNG platform, the overall results indicate that the safety gap is effective in reducing overpressure in two adjacent congestions. However, for the explosion scenario where the flame is propagating through several safety gaps to the far field congestion, the safety gap mitigates overpressure only in certain explosion protecting targets. Two series of artificial configurations are modeled to further investigate the explosion scenarios with more than two safety gaps in one direction. It is concluded that the optimal safety gap design in overpressure mitigation for the cylindrical FLNG platform is to balance the safety gap distance ratio in the congested regions.     

烟气同时脱硫脱硝技术进展研究

中国二氧化硫和氮氧化物的排放所引起的污染越来越严重,国家治理大气污染的力度逐步加大.现阶段单独脱硫脱硝的技术已经很成熟,考虑到经济高效的问题,烟气同时脱硫脱硝技术是当前烟气净化技术研究的热点之一.研究开发经济、高效、简单的烟气脱硫脱硝一体化技术十分必要和紧迫.本文介绍了几种典型烟气同时脱硫脱硝技术原理及其研究现状,分析了其原理及优缺点,对几种工艺进行了技术和经济分析.最后对脱硫脱硝一体化技术的发展前景作了展望.     

中国化工园区雨排系统环境风险防控研究

雨排系统是化工园区重要的基础设施,如果没有建立有效的环境风险防控体系,污染物有可能通过园区雨排系统排入外环境,造成重大环境影响.目前,中国已出台的有关化工园区雨排系统环境风险防控的政策法规缺少强制性和统一性,监管标准缺失导致环保部门缺乏行之有效的监管手段,园区规划阶段协同机制的不健全也增加了后期监管的难度.鉴于目前中国化工园区雨排系统环境风险防控方面存在的问题,建议国家和地方加快监管标准出台,强化相关政策的落实,优化园区雨排系统,实施分类、分级管控,同时加强企业的监管.     

医疗废物高温蒸汽处理工艺的二次污染控制——以孝感市医疗废物处置中心为例

以孝感市医疗废物处置中心为例,介绍了高温蒸汽处理过程的二次污染控制工艺。结果表明:采用生物脱臭处理工艺,废气中的恶臭污染物可以达到《恶臭污染排放控制标准》(GB 14554—1993)相应排放速率限值要求;采用生化和物化相结合的废水处理工艺,出水水质可以满足《污水综合排放标准》(GB 8978—1996)的二级排放标准要求。     

基于云模型的页岩气开发环境影响评价

从大气环境、噪声与土壤环境、水环境和生态、安全与可持续4个方面构建页岩气开发环境影响指标体系,并建立基于熵权法和云模型评价法的页岩气环境影响评价模型。针对四川省某国家级页岩气示范区进行实证分析,结果表明:该地区页岩气开发环境影响处于中等程度。页岩气开发对水环境影响最大,其次是对大气环境的影响,再次是对噪声与土壤环境,对生态、安全与可持续方面影响相对最小。该模型的评价结果与页岩气开发环境影响现状相符,最后根据评价结果提出相关政策建议。     

保护层开采工作面采空区瓦斯分层治理

为实现保护层开采工作面生产过程中瓦斯不超限,在分析工作面瓦斯来源的基础上,提出了保护层开采工作面竖向分层治理瓦斯的思路。根据相似模拟结果,分析了采空区瓦斯流动范围和流动范围内孔隙率、风阻分布特征。采用数值模拟分析了Y型通风、Y型通风+采空区埋管及Y型通风+采空区埋管+高抽巷+高位钻场3种瓦斯治理方式下采空区瓦斯体积分数场,结果表明:采空区瓦斯体积分数在竖直方向和水平方向均具有典型的递变特征,距工作面越远,距煤层越高,瓦斯体积分数越大;合适位置的煤层顶板高抽巷对抽采来自上邻近层的瓦斯具有较好的效果,试验条件下高抽巷抽采瓦斯量达到了总量的36.4%~63.6%;沿充填墙的采空区埋管不能完全拦截下层采空区进入沿空巷的采空区瓦斯,随沿空巷长度增加,瓦斯体积分数增大,建议沿空巷长度控制在250 m范围内。     

Chlorothalonil binding to aquatic humic substances assessed from gas purge studies

Abstract

Fate of the fungicide chlorothalonil (TCIN) binding to dissolved organic acid fractions was quantified using gas‐purge desorption studies. Binding studies were conducted to measure the dissolved organic carbon partition constant (K_DOC) with aquatic fulvic and humic acid fractions purified from cranberry bog water. Desorption studies at DOC concentrations up to 50 mg L^‐1 resulted in mean log K_DOC values of 4.63 (s.d.=0.5, n=8) and 4.81 (s.d.=0.7, n=7) for fulvic and humic acids, respectively. These values deviated from reported K_OC (organic carbon) values by 0.5 to 1.5 orders of magnitude. The relationship between K_OC and K_DOC did not conform to accepted ratios of 10: 1 to 3: 1, although these studies were conducted with the strong hydrophobic fraction of DOC. Binding was rapid suggesting hydrophobic partitioning or weak Van Der Waals forces as binding mechanisms. The strong binding potential for TCIN to aquatic humic substances corresponds to increased solubility in the aqueous system. Sorption to DOC suggests a possible transport mechanism which may result in elevated concentrations of TCIN in cranberry bog systems.     

Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos

The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography–Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.