Treatment of tannery wastewater by electrocoagulation

Treatment of tannery wastewater by electrocoagulation with low cell current(≤1A)and soluble electrodes(mild steel electrodes and aluminum electrodes)was studied.Compared with aluminum electrodes,mild steel electrodes were more effective for the removal of sulfide,with a removal efficiency of over 90%.But during the treatment process,black color precipitate typical to iron(Ⅱ)sulfides was produced.While aluminum electrodes were effective to eliminate the colority of the effluent,the removal efficiency of sulfide was lower than 12%.The mechanisms of the removal of chemical oxygen demand,ammonia,total organic carbon,sulfide and colority with the two soluble electrodes(mild steel and aluminum electrodes)were discussed in detail.In order to exert the predominance of diffenent types of electrodes,the tannery wastewater was treated using mild steel electrodes first followed by the filter and finally by the aluminum electrodes,the elimination rates of chemical oxygen demand,ammonia,total organic carbon,sulfide and colority were 68.0%,43.1%,55.1%,96.7% and 84.3%,respectively,with the initial concentrations 2413.1 mg/L,223.4 mg/L,1000.4 mg/L,112.3 mg/L and 256 dilution times,respectively.The absorbance spectra and energy consumption during electrocoagulation process were also discussed.     

Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

The electrochemical reduction characteristics of carbon tetrachloride (CT) were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders' iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders' iron. The entire CT in 350 ml aqueous solution with 320 mgL was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with FeCu ratio of 10:1 (ww) were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were di?erent. The degradation rate was not significantly in?uenced by pH in the catalyzed Fe-Cu process; in Master Builders' iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode (Cu) and anode (Fe) compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.     

污泥性质对动态膜形成和膜污染的影响

以一体式尼龙筛网动态膜生物反应器（DMBR）为研究体系,探讨了正常污泥、膨胀污泥和解体污泥的动态膜形成和膜污染特点,并从胞外聚合物（EPS）、相对疏水性（RH）、污泥混合液粘度（μ）、接触角这些物化性质角度定量研究膜污染机理.研究结果表明,膨胀污泥由于丝状菌累积导致严重的泥饼层污染;解体污泥由于胶体颗粒和可溶性物质沉积...     

大气颗粒物物理化学属性致病效应与损伤机制的研究进展

近些年,我国大气颗粒物所带来的健康问题越发突出,由此产生的环境疾病日益引起人们的广泛关注。大量的流行病学和毒理学研究发现,大气颗粒物能引起呼吸系统、心血管系统、神经系统、免疫系统等的损伤,造成新生儿出生缺陷,增加罹患癌症的风险,且与人群发病率和死亡率上升有关。但是由于大气颗粒物物化属性比较复杂,一种或几种损伤机制并不能完全解释其与致病效应的关系,因此具体的损伤机制目前还没有统一的说法,大气颗粒物物理化学属性与致病效应的关系仍在探索当中。本文从大气颗粒物的粒径、浓度、比表面积、来源、成分等基本属性入手,剖析其基本特点和可能影响健康的原因,探讨大气颗粒物通过氧化损伤途径诱导致病效应,并结合当前大气颗粒物健康影响研究现状提出在未来研究中应注重的相关内容。     

微型碎石管注桩治理深部软岩巷道底鼓新方法

针对造成巷道底鼓的物理和力学两种重要机制,研究并提出微型碎石管注桩治理深部软岩巷道底鼓的新方法。在物理机制方面,微型碎石桩具有渗透性极好的特点,在巷道施工和使用期间可汲取岩体中的渗水并透过碎石桩中的插管排出,从而降低软岩层因遇水膨胀导致的变形;在力学机制方面,微型碎石桩一方面通过钻孔置换出少部分底板软岩,从体量上减少变形岩体,另一方面能利用碎石桩体的侧向可压缩性耗散岩体水平变形,底板岩层中的水平地应力得以释放,极大减缓了促使底鼓变形的力学作用;通过微型碎石桩中的插管注浆加固底板岩体,提高了底板复合地基整体承载力。通过数值分析,阐明该方法在治理软岩巷道底鼓机制上的有效性。     

Transnational environmental standards in Eastern Europe: an assessment of companies in Lithuania and their adoption motives

During the last few decades, many environmental certification schemes were developed to enhance transparency and traceability within commodity chains. Most of them are transnational schemes, which means that they were created by non-governmental organizations and/or the private sector, independently from governments. This article aims to examine how local certified companies assess the functioning of such private environmental certification. It presents the results of an empirical research about the expectations and satisfaction of certified companies in Lithuania. Empirical data were collected through a survey with 90 companies certified by one of the three major transnational environmental standards: Forest Stewardship Council (FSC) for the forestry and logging, Marine Stewardship Council (MSC) for fishing and aquaculture, and Oeko-Tex for the production of textiles. The results revealed that most companies have adopted these standards quite recently, indicating that it is generally a new trend in Lithuania. The findings suggest that the overall expectations with the standards’ functions, such as sending signals to clients or getting more market share, were higher than the satisfaction in all cases. The main transnational environmental standard adoption motive was the client demand. It turned out, however, that later after the certification procedure the majority of the companies were most satisfied with the market opportunities that opened up. Furthermore, the companies expected certification to operate best as a market-based mechanism; but most satisfactory performance was accredited to the signalling mechanism. Research suggests that certification provides various benefits for the companies, but the expectations might be rather exaggerated.     

区域环境健康问题调查的实施机制

环境健康调查实施机制的合理性直接决定了大型区域环境健康调查的执行效率和最终结果.鉴于区域环境健康问题调查涉及内容多学科、执行流程多环节、实施过程有交叉的复杂特点,围绕环境健康传导链特征解析的调查实质,就如何高效组织区域环境健康调查的参与人员和技术力量等实施机制问题进行了探索.在总结我国大型环境健康调查工作实施经验的基础上,提出所有环境健康问题调查人员分属作用分明的“四大功能”角色定位,以及区域环境健康问题调查的“九步运行”技术流程等相关论断.相关研究结果直接支持了若干大型环境与健康调查工作,为进一步丰富区域环境健康问题调查理论提供了借鉴.     

南京夏季大气臭氧光化学特征与敏感性分析

对流层臭氧（O₃）主要由氮氧化物（NO_x）和挥发性有机物（VOCs）经过一系列光化学反应生成,反应过程呈现复杂的非线性关系.为深入了解O₃的光化学特征及生成机制,利用2018年夏季大气O₃与VOCs的观测数据,结合大气零维框架模拟模型F0AM-MCM,研究O₃超标日和非O₃超标日的O₃光化学特征之间的差异性.观测结果表明,O₃超标日期间φ（O₃）和φ（TVOCs）的平均值分别为47.8×10^-9和49.0×10^-9,为非O₃超标日期间O₃（26×10^-9）和TVOCs（30×10^-9）体积分数的1.8倍和1.6倍.使用F0AM模型,借助EKMA曲线和RIR分析等识别O₃敏感性,发现南京市O₃超标日和非O₃超标日O₃的形成均主要受VOCs和NO_x的协同控制.F0AM-MCM模拟结果表明,在O₃超标日,·OH和HO₂的日平均混合比分别是非O₃超标日的1.3倍和1.8倍,表明O₃超标日期间具有更强的大气氧化能力,且·OH和HO₂的形成和损失速率也有明显的增加,表明自由基循环的增强.此外,O₃超标日的O₃生成速率明显高于非O₃超标日,从而导致了O₃超标日的O₃净生成速率明显高于非O₃超标日.以上发现提高了对南京夏季O₃超标日大气O₃光化学特征的认识.     

二恶英类毒理学研究新进展

二恶英类的毒理学研究已有30多年的历史,在一系列二恶英类污染事件和国际公约的推动下,近年来二恶英类毒理学研究成为备受关注的热点.综述了近年来二恶英类毒理学研究的一些新的观点和发现,涵盖了分子毒性机理、致癌毒性、非致癌毒性和非致癌剂量-效应风险度评价方法等诸多领域,其中TCDD毒性效应的负反馈调节机制研究和对人体健康非致癌效应的影响引起了国内外广大毒理学研究工作者的关注.在总结前人研究的基础上对二恶英类毒理学研究今后的发展进行了展望.     

低成本含磷材料修复环境重金属污染的研究进展

低成本含磷材料包括磷灰石、骨粉、无机磷肥及无机磷酸盐,其对环境重金属污染的修复值得引起生态学、环境学更广泛的重视.详细介绍了:(1)各类低成本含磷材料结构性质;(2)含磷材料在修复土壤、沉积物、水体重金属污染方面的应用;(3)含磷材料修复环境重金属污染的机理及影响因素;(4)含磷材料修复环境重金属污染的效果评价等方面的研究进展及发展前景.