形变功率脉冲电源作用下印染废水处理研究

为了克服常规直流电源电凝聚法处理废水电耗和电极损耗大，电极易钝化的缺点，研究了不同电压波形的净化电源处理印染废水的方法.利用实验方法得到了不同电压波形下的电能净化效率，比较了直流(DC)和周期换向方波对电极钝化现象的影响.同时基于电凝聚机理，讨论了形变功率脉冲电源作用下电凝聚过程机理表现出来的双电层电容效应，液相传质和吸附与脉冲吸附等特点.研究表明，与传统的直流方式相比，利用周期换向方波对印染废水进行处理，可以显著降低电耗和电极损耗，克服电极钝化的问题，降低经济成本，促进电凝聚法在实际工程中的应用.     

Trivalent chromium removal by electrocoagulation and characterization of the process sludge

Removal of chromium compounds from wastewater is a known pollution control challenge for environmental engineers. In this present work Cr³⁺ was removed from wastewater by electrocoagulation (EC) using Al electrodes in a batch cell. Results indicate that EC with an Al electrode can reduce Cr³⁺ concentration below 2.0 mg L^?1, its discharge limit. At higher stirrer speed, Cr³⁺ removal increases owing to enhanced contact with the Al³⁺ species. Cell current density controls the rate of Al dissolution and solution pH that affects the Cr³⁺ removal significantly. pH elevation during EC is due to accumulation of OH^? ions forming a supersaturated solution of Al³⁺ species. Supersaturation with respect to Al(OH)₃(s) is attributed to incomplete precipitation of aluminum hydroxide in the dynamic (transient) state and subsequent precipitation when cell current is stopped. Sludge produced in the process can be classified as non‐hazardous according to the European Waste Catalogue. Disposal cost of this dried sludge is estimated to be $ 0.144 (INR 7.20) per m³ of tannery effluent treating an initial solution of 1000 mg L^?1 Cr³⁺ to about 2.0 mg L^?1 Cr³⁺. Batch gravity settling characteristics of the electrocoagulated metal hydroxide sludge (EMHS) at different initial sludge loadings (as generated at different current density) is also investigated. Batch sedimentation flux is reported from experimental settling velocity and concentration of sludge. Copyright © 2007 Society of Chemical Industry     

脉冲电絮凝处理含镉重金属废水

采用脉冲电絮凝方法处理含镉重金属废水, 考察了通电时间、pH值、离子强度、电流密度及占空比等因素对溶液中Cd²⁺去除效果的影响, 并结合相应的计算公式核算了相应的电耗和铝板消耗。实验结果表明, 在通电时间为60 min, 电流密度为10 mA/cm², 电导率为7.8 ms/cm, 占空比2.5, pH值7.82的条件下, Cd²⁺去除率达到了99.86%, 电耗和铝板消耗分别为0.832 kWh/m³和100.7 g/m³。     

Removal of nonylphenol ethoxylates by electrochemically-generated coagulants

This study investigated the behaviour of aluminium and carbon steel electrodes in the presence and absence of nonylphenol ethoxylates (NPnEO, where n is the number of ethoxylate groups in the molecule) and NPnEO removal by electrochemically-generated coagulants. The electrode processes were studied by potentiodynamic polarization measurements to determine the influence of surfactant addition (ethylene oxide units and organic load), inorganic composition and pH. The polarization curves showed the extent of the involvement of NPnEO in the electrode processes. Their influence appeared clearly in the range of anodic activation, depending on the number of ethoxylate groups. Removal of NPnEO from simulated wastewaters was carried out in two electrocoagulation cells with vertical and horizontal electrodes, respectively. The removal efficiencies calculated from the chemical oxygen demand before and after treatment were 30–50% for NP16EO and NP40EO, and 40–80% for NP4EO. The hydrophilic-lipophilic balance number for NP4EO indicated a relative ratio of polar and non-polar groups lower than for the other two surfactants, which was in favour of better NP4EO removal. The experiments showed the processes in the bulk (bridging of electrochemically-generated polymeric species and adsorption of surfactants) were predominant over the involvement of NPnEO in the electrode processes, which were only responsible for the electrogeneration of coagulants.     

Recovery of Silver and Gold from Cyanide Solution by Magnetic Species Formed in the Electrocoagulation Process

Cyanidation is the predominant process by which gold and silver are recovered from their ores in metallurgical operations, and it is recognized that the Carbon in Pulp, the Merrill–Crowe, the Ion Exchange, and Solvent Extraction processes are used for concentration and purification of gold and silver from cyanide solutions. Among other available options for recovery of precious metals from cyanide solutions, Electrocoagulation (EC) is a very promising water and wastewater electrochemical technique that does not require high concentrations of silver and gold in cyanide solutions to yield excellent results. In this work, an introduction to the fundamentals of the EC process is given, followed by the conditions and results of the EC test run for removal of precious metals from cyanide solutions, and finally the characterization of the solid products formed during the EC process with X-ray Diffraction, SEM, and Transmission Mossbauer Spectroscopy. Results suggest that magnetite particles and amorphous iron oxyhydroxides are present (Lepidocrocite and Gohetite). With the EC process, the achieved removal efficiency of silver and gold from cyanide solutions, within 5 min, exceeded 99%.     

电絮凝技术在水处理中的应用

电絮凝是一种环境友好型技术。电絮凝方法占地面积小,不需要添加化学试剂,污泥量少,操作简单,可以有效去除水中的COD、重金属、色度、氟化物和有毒有害物质。本文介绍了电絮凝处理水的基本原理,综述了电絮凝在水处理中的应用及存在的不足,提供了解决方法。针对能耗较高的问题,可从改进电源、研制新电极和与其他技术连用等方面研究。     

电絮凝在煤化工废水预处理中的脱除氨氮实验研究

通过采用电絮凝法处理煤化工企业的废水,研究了电流密度,Cl离子浓度,初始pH,极板间距等因素对去除氨氮效果的影响。结果表明,氨氮去除率随电流密度的增大而增加,随极板间距的增大而减小,且在中性和弱碱性,一定氯离子浓度环境下氨氮去除效果较好。本实验的最佳参数为pH 7.0,电流密度为60 mA/cm2,极板间距为1.0 cm,氯离子浓度为0.7 mol/L。     

利用电絮凝法深度处理二级处理生活污水出水的研究

采用双铝极板,利用电絮凝法对城市生活污水二级处理出水进行处理,以氨氮、总磷和COD的去除率等为指标,通过探索电解时间、极板间距、电流密度、pH值等参数的单因素影响分析,研究各参数对处理效果的影响,确定最佳条件。实验表明,采用双铝极板电絮凝法深度处理城市生活污水二级处理出水可有效的去除氨氮、总磷和COD。     

应用铝和铁电极电化学处理酒精废醪蒸馏废水(英文)

Electrochemical treatment of distillery spent wash was carried out using different combinations of aluminum and iron electrodes in batch mode of operation.The spent wash was characterized for various parameters as per standard method of analysis and the treatment results were analyzed in terms of chemical oxygen demand(COD) removal efficiency of the spent wash.The experiments were performed to study the effect of operating parameters such as current density,pH of the spent wash,agitation speed,electrolysis time and the distance between the electrodes on the COD removal efficiency of the spent wash.It was observed that aluminum electrodes were more suitable for treatment of distillery spent wash as compared to iron electrodes.The maximum COD removal efficiency of 81.3% was obtained with Al-Al electrodes at the current density of 0.187 A·cm-2 and pH 3 for an electrolysis time of 2 h.     

脉冲电絮凝处理电镀废水的工艺优化与应用

以实际电镀厂废水为研究对象,采用铁电极板电絮凝技术,考察比电流、溶液初始pH值、占空比和曝气强度等参数对废水中镍和铬去除效果的影响,并利用响应面法优化了电絮凝工艺。结果表明,当比电流为122 A/m^3、占空比为48%、初始p H值为7. 1、曝气强度为2. 4 L/L时,电解30 min后,对Ni²⁺、Cr⁶⁺和总铬的去除率分别为99. 65%、100%、100%,比能耗为0. 757kW·h/m^3,与传统的单因素试验相比,降低了11. 87%。实际工程废水的处理规模为30 m^3/h,400多天的运行效果表明,经响应面优化的电絮凝工艺运行稳定,出水水质达标。