Organic matter extracted from activated sludge with ammonium hydroxide and its characterization

In order to characterize the organic properties of waste activated sludge in a wastewater treatment plant,organic matter within sludge was extracted with NH 3 ·H 2 O preferentially,and subsequently fractionated into five fractions using XAD-8/XAD-4 resins.Up to a 63.8%-71.1% of organic matter within the sludge could be efficiently extracted by NH 3 ·H 2 O.Fractionation results showed that hydrophobic acid and hydrophilic fraction were two main components among the sludge organic matter (accounting for 32.2% and 48.0% of the bulk organic matter,respectively),whereas transphilic acid,hydrophobic neutral and transphilic neutral were quite low (accounting for 9.2%,5.8% and 4.8%,respectively).Despite that the extractant of NH 3 ·H 2 O showed a relatively higher extraction efficiency of the aromatic components,the relatively low aromaticity of the organic fractions implied that those non-aromatic components could also be effectively extracted,especially for neutral and hydrophilic fractions.In addition,acidic fractions contained more aromatic humic-like components,whereas the neutral fractions had a greater content of aromatic proteins and soluble microbial byproduct-like components.Extraction of sludge organics with NH 3 ·H 2 O and subsequential fractionation using XAD resins could be a novel method for further characterization of sludge organics.     

Experimental investigation of adsorption capacity of anthill in the removal of heavy metals from aqueous solution

In the present work, the adsorption capacity of anthill was investigated as a low‐cost adsorbent to remove the heavy metal ions, lead (II) ion (Pb²⁺), and zinc (II) ion (Zn²⁺) from an aqueous solution. The equilibrium adsorption isotherms of the heavy metal ions were investigated under batch process. For the study we examined the effect of the solution's pH and the initial cations concentrations on the adsorption process under a fixed contact time and temperature. The anthill sample was characterized using a scanning electron microscope (SEM), X‐ray fluorescence (XRF), and Fourier transform infrared (FTIR) techniques. From the SEM analysis, structural change in the adsorbent was a result of heavy metals adsorption. Based on the XRF analysis, the main composition of the anthill sample was silica (SiO₂), alumina (Al₂O₃), and zirconia (ZrO₂). The change in the peaks of the spectra before and after adsorption indicated that there was active participation of surface functional groups during the adsorption process. The experimental data obtained were analyzed using 2‐ and 3‐parameter isotherm models. The isotherm data fitted very well to the 3‐parameter Radke–Prausnitz model. It was noted that Pb²⁺ and Zn²⁺ can be effectively removed from aqueous solution using anthill as an adsorbent.     

浸入式短流程超滤膜生产工艺过程膜污染的形成与控制

以江苏芦泾水厂膜技术改造工程为对象,从水质、膜工艺特征结合生产运行过程以及污染膜的清洗进行了分析,目的是了解膜污染的组分构成,评价不同清洗剂的清洗效果,获取较优的清洗顺序.结果表明,原水以憎水酸(HOA)和亲水组分(HIM)为主体,质量分数各占40.34%和28.48%.溶解性有机物(DOM)则以芳香性蛋白质Ⅱ类物质为...     

矿物超细颗粒的形成机制、结构特征及其环境行为和效应

矿物超细颗粒在自然环境中普遍存在,具有独特的环境行为和效应,对元素地球化学循环、污染物迁移转化和生态环境演变等有重要影响.矿物超细颗粒的环境行为和效应与其形成过程和结构特征密切相关.综述了物理、化学和生物过程驱动的矿物超细颗粒的形成机制,介绍了用于表征矿物超细颗粒结构特征的显微镜、光谱、质谱和同步辐射技术,分析了矿物超细颗粒在环境中的迁移转化及其与污染物的吸附、氧化还原和催化转化作用,总结了矿物超细颗粒的食物链积累、生物和生态毒性等环境效应,并对颗粒结晶路径、风险管控和微纳界面调控等重要研究方向进行了展望.超细颗粒是连接微观物质与宏观矿物晶体之间的桥梁,全面认识复杂基质中矿物颗粒的环境属性及其与污染物的微观作用机制,有助于指导矿物超细颗粒在环境污染修复中的应用,从而优化功能材料的设计,促进绿色低碳纳米技术的发展.     

Physico-chemical characterization of Residual Household Waste for energy recovery in insular territories: Case study of Reunion Island

Waste-to-energy is a promising approach to face the current challenge of waste overproduction in Reunion Island, a French territory. In this particular context of an isolated and tropical territory, it is essential to study the properties of potential feedstocks to choose the most appropriate conversion process. This article reports on the composition of Residual Household Waste from Reunion Island and its physico-chemical parameters. Twelve representative samples of Residual Household Waste were subjected to thermal and elemental analysis. The results showed that their composition had a significant influence on the physico-chemical properties, including calorific value. Residual Household Waste from the selective sorting (rich in wood, plastic, and sanitary textiles) as well as dry mixed RHW are the most interesting for energy recovery. Due to their high volatile matter and high carbon content, and their low moisture content, these types of waste have a high calorific value exceeding 18 MJ/kg. Furthermore, the RHW sample comply with the environmental and health criteria applied by French regulations concerning halogen and heavy metal. Thus, it seems that Residual Household Waste can be an alternative to conventional fuels used in incineration or pyro-gasification processes. However, the study also points the need for a pre-treatment process for these wastes. Indeed, it is necessary to sort them correctly in order to avoid the risks of pollution and important maintenance. And more importantly, drying beforehand is unavoidable to improve combustibility and obtain optimal energy conversion.     

冬季不同污水处理工艺对溶解性有机物的去除

以东北地区4个城市污水处理厂为研究对象,考察冬季不同污水处理工艺对溶解性有机物(DOM)组分的去除效果,以及对DOM组分的光谱学特性和卤代活性的影响.利用XAD树脂将DOM分为5个部分:疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).结果表明,A/O法、曝气生物滤池、浮动填料法和A2/O法对DOM都具有较高的去除能力,其中曝气生物滤池对DOM的处理效果最好.经4种污水处理工艺处理后,5种组分的芳香性和三卤甲烷生成活性(STHMFP)均升高.A2/O法对HPO-A和TPI-A的芳香性增强程度最高,而曝气生物滤池对HPO-N,TPI-N和HPI的芳香性增强程度最高.浮动填料法对HPO-A,TPI-A和HPI的STHMFP升高最显著,A2/O法对HPO-N的STHMFP增加最显著,曝气生物滤池对TPI-N的STHMFP升高最显著.4种污水处理工艺对HPI中荧光物质的去除率高于非荧光物质.而对于其他4种DOM组分来说,不同的污水处理工艺对不同荧光峰的改变不相同.     

Optimizing synthesis conditions of nanoscale zero-valent iron (nZVI) through aqueous reactivity assessment

Nanoscale iron particles (nZVI) is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a facile method to screen the reactivity of candidate nZVI materials produced using different methods or under varying synthesis conditions has yet been established. In this study, four reaction parameters were adjusted in the preparation of borohydride-reduced nZVI. The reductive properties of the resultant nanoparticles were assayed independently using two model aqueous contaminants, Cu(II) and nitrate. The results confirm that the reductive reactivity of nZVI is most sensitive to the initial concentration of iron precursor, borohydride feed rate, and the loading ratio of borohydride to ferric ion during particle synthesis. Solution mixing speed, in contrast, carries a relative small weight on the reactivity of nZVI. The two probing reactions (i.e., Cu(II) and nitrate reduction) are able to generate consistent and quantitative inference about the mass-normalized surface activity of nZVI. However, the nitrate assay is valid in dilute aqueous solutions only (50 mg·L⁻¹ or lower) due to accelerated deactivation of iron surface at elevated nitrate concentrations. Additional insights including the structural and chemical makeup of nZVI can be garnered from Cu(II) reduction assessments. The reactivity assays investigated in this study can facilitate screening of candidate materials or optimization of nZVI production parameters, which complement some of the more sophisticated but less chemically specific material characterization methods used in the nZVI research.     

深圳市大气中多环芳烃的污染特征与来源识别

利用大流量主动采样器于2009年12月~2010年1月及2010年6月,分冬季与夏季两批次对深圳市13个点位进行大气样品采集,检测其气相及颗粒相中总的多环芳烃(PAHs)浓度.结果表明,冬季深圳市大气中总PAHs的浓度为17.9~92.3ng/m3,平均值为45.3ng/m3;夏季总PAHs浓度范围为8.64~96.3ng/m3,平均值为32.2ng/m3.两个季节PAHs单体中均以3~4环为主,占总浓度的75%以上;单个组分与总量的相关性分析表明,夏季明显优于冬季.来源分析表明,冬季大气中PAHs来源比夏季更为复杂,通过特征分子比值法推断冬季PAHs主要来源于石油源、燃煤、机动车尾气排放;夏季主要来源于机动车尾气排放.利用毒性当量因子法和致癌风险评价其污染水平和毒性风险,结果表明深圳市大气中PAHs污染与国内部分城市相比,处于较低水平.     

Assessment and management of urbanization-induced ecological risks

The urban ecological risk incurred during the processes of urbanization has been constantly accumulating, creating a severe challenge for China to achieve sustainable urban development. At present, research on systematic evaluation of urban ecological risks is still inadequate, especially at an urban ecosystem level. In this special issue, we use Xiamen City as an example to identify the sources and receptors of urban ecological risks, to develop a methodology system of urban ecological risk assessment, and to propose a method for the management of urban ecological risks. This special issue contains 11 research articles resulting from a comprehensive research project funded by China’s National Natural Science Foundation. The innovations reported in this special issue include a framework of urban ecological risk assessment and a standardized procedure for carrying out urban ecological risk assessment using multiple stressors and endpoints.     

机械化学法修复柴油污染土壤的效率、产物及影响

针对常规污染土壤修复处理方法存在有毒降解产物、容易产生二次污染等问题,本研究采用行星球磨仪研究了机械化学法（MC）对柴油污染土壤的修复效能,利用GC/MS对柴油烃组分的降解产物进行分析,并采用SEM、XRD、BET、FTIR和TGA等方法对不同处理条件下的土壤样品进行表征.结果表明,MC处理在0.5~4.0 h内对土壤中总石油烃（TPH）的去除率可达95%以上.随着初始TPH浓度和球土质量比的升高,TPH去除率随之提高.采用MC处理后柴油组分降解难度顺序如下：烷烃<烯烃<环烷烃<芳香族化合物.在球磨处理4 h后,未检出有毒有害残留物质.球磨后土壤粒径变小,表面变粗糙,粘土矿物中的硅氧四面体暴露在土壤表面,矿物结构的结晶度逐渐降低,晶体结构逐渐破裂或变形,可在土壤表面形成富电子区域或促使土壤具有更高的反应活性,这是机械化学法高效降解柴油的主要机制.其次,土壤有机质的主要官能团受到破坏,纳米级孔隙容量降低,从而降低了土壤组分的吸附能力,增加了柴油的有效性,也有助于柴油的解吸和机械化学降解.此外,随着球磨时间的增加,土壤有机碳（SOC）含量先增加后下降,但均高于处理前.可见,MC处理可以快速彻底降解土壤中的柴油,且有利于增加土壤有机碳含量,对于石油烃污染土壤修复具有较好的应用潜力.