Electrochemical remediation of acid mine drainage

Acid mine drainage (AMD), which has long been a significant environmental problem, results from the microbial oxidation of iron pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. Electrochemical treatment of AMD offers possible advantages in terms of operating costs and the opportunity to recover metals, along with cathodic reduction of protons to elemental hydrogen. This work describes the electrolysis of synthetic AMD solutions containing iron, copper and nickel and mixtures of these metals using a flow-through cell divided with an ion exchange membrane. Iron was successfully removed from a synthetic AMD solution composed of FeSO₄/H₂SO₄ via Fe(OH)₃ precipitation outside the electrochemical cell by sparging the electrolysed catholyte with air. The work was extended to acidic solutions of Fe²⁺, Cu²⁺, and Ni²⁺, both singly and in combination, and to an authentic AMD sample containing principally iron and nickel.     

Inhibition of hematite on acid mine drainage caused by chalcopyrite biodissolution

Even though biodissolution of chalcopyrite is considered to be one of the key contributors in the formation of acid mine drainage (AMD), there are few studies to control AMD by inhibiting chalcopyrite biodissolution. Therefore, a novel method of using hematite to inhibit chalcopyrite biodissolution was proposed and verified. The results indicated that chalcopyrite biodissolution could be significantly inhibited by hematite, which consequently decreased the formation of AMD. In the presence of hematite, the final biodissolution rate of chalcopyrite decreased from 57.9% to 44.4% at 20 day. This in turn suggested that the formation of AMD was effectively suppressed under such condition. According to the biodissolution results, mineral composition and morphology analyses, and electrochemical analysis, it was shown that hematite promoted the formation and accumulation of passivation substances (jarosite and Cu_2-xS) on chalcopyrite surface, thus inhibiting the biodissolution of chalcopyrite and limiting the formation of AMD.     

Mextral V10–Mextral 973H体系脱除酸性矿山废水中重金属的研究

矿山选、冶废水成分复杂、水量大,目前所用方法对重金属的脱除效果不理想、成本高,为解决矿山废水重金属污染问题,开发适用于酸度较高、重金属浓度较低、对钙、镁离子有抑萃作用的协同萃取法脱除并回收废水中的重金属。通过绘制萃取等温线、FT-IR及紫外吸收光谱对Mextral V10–Mextral 973H协同萃取体系进行分析,研究了萃取剂浓度、有机相和水相体积比(简称相比,O/A)和Mextral V10皂化率对废水中重金属分离影响。结果表明,Mextral V10–Mextral 973H协同萃取体系能有效脱除酸性废水中Cu2+, Pb2+, Cd2+和Zn2+。在10vol% (Mextral V10+Mextral 973H)+90vol% Mextral DT100,Mextral V10:Mextral 973H=1:1的最佳实验条件下连续萃取六次,萃后废水中Cu2+, Cd2+, Zn2+, Pb2+, Mg2+和Ca2+的萃取率分别为99.1%±0.1%, 99.9%±0.02% 99.5%±0.05%, 97.6%±0.03%, 10.11%±0.1%和18.3%±0.05%,废水中残留Cu2+, Zn2+, Cd2+和Pb2+浓度分别为1.720±0.10, 0.256±0.03, 0.054±0.01和0.929±0.01 mg/L,低于GB8978-1996中第一类污染物最高允许排放标准值。     

Removal of heavy metals and cyanide from gold mine wastewater

This paper reviews the technology and biotechnology to remove heavy metals (such as copper, arsenic, lead and zinc) and cyanide from contaminated wastewater. The paper places special emphasis on gold mine wastewater and the use of low cost materials as sorbent. Various biological as well as physicochemical treatment processes are discussed and compared on the basis of costs, energy requirement, removal efficiency, limitations and advantages. Sorption using natural plant materials, industrial and agricultural waste has been demonstrated to have the potential to replace conventional methods for the removal of heavy metals because of its cost effectiveness, efficiency and the local availability of these materials as biosorbent. The parameters affecting sorption, such as initial ion concentration, pH, sorbent dosage, particle size and temperature, are discussed. The overall treatment cost of metal and cyanide contaminated wastewater depends on the process employed and the local conditions. In general, technical applicability, cost‐effectiveness and plant simplicity are the key factors in selecting the most suitable treatment method. Copyright © 2010 Society of Chemical Industry     

德兴铜矿酸性矿山废水污染分析

本文对德兴铜矿的环境污染状况从污染物产生机理、污染水质水量以及污染源分布等进行了综合分析，为下一步铜矿的环境治理提供依据。     

人工湿地在酸性矿山废水中的应用

酸性矿山废水对环境污染和破坏较为突出,对酸性矿山废水进行治理越来越受到重视。文章介绍了酸性矿山废水的来源与危害,人工湿地治理酸性矿山废水的机理及在酸性矿山废水中治理的应用前景。     

Removal of heavy metals in plating wastewater using carboxylated alginic acid

Potentially, biosorption is an economic process for metal sequestering from water. Carboxylated alginic acid showed high uptake capacities for heavy metals of 5-6 meq/g dry mass. For application to actual plating waste-water, the carboxylated alginic acid was immobilized using PVA. In order to remove chelating or organic materials in plating wastewater, oxidation using sodium hypochlorite was performed as a pretreatment. When carboxylated alginic acid bead was applied in a packed-bed contactor, the breakthrough point of copper ion in the acid-alkaline wastewater appeared around 350 bed volumes; the breakthrough point of nickel ion in the chelating wastewater emerged around 200 bed volumes. The adsorption capacity for heavy metal of the carboxylated alginic acid bead was higher than that of a commercial ion exchanger (IR-120 plus) in plating wastewater.     

硫酸盐还原菌法固定酸性矿山废水中重金属的研究进展

硫酸盐还原菌(SRB)法是一种极具潜力的酸性矿山废水(AMD)处理技术,如何将多种重金属分级沉淀并且分相分离出来,是SRB工艺走上工程应用的关键。本文综述了SRB法固定AMD中重金属的国内外研究进展,主要包括SRB法去除AMD中重金属的原理、SRB法分级沉淀AMD中多种重金属的工艺(分离式多级pH控制工艺及厌氧折流板反应器工艺)和SRB法厌氧污泥中金属硫化物的生物矿化(SRB介导的生物矿化成矿、生物矿化成矿影响因素及生物矿化过程微观机理),分析了此方面研究工作存在的问题。最后文章针对SRB法的深入研究及应用进行展望,认为硫酸盐还原体系中硫化物成矿的调控、成矿物相演变与微生物群落演替过程的解析以及矿化固定AMD中重金属成矿机理的探索将是今后重点关注的研究内容。     

硫酸盐还原菌处理酸性矿山废水的技术及思考

含高浓度硫酸盐酸性矿山废水的污染是一个全球性的问题。利用硫酸盐还原菌（SRB）可对含硫酸盐的酸性矿山废水进行生物处理．在厌氧条件下．SRB以碳源为电子供体将SO4^2-还原到S^2-并释放出碱度,使废水pH值提高．S^2-可用物化法或生化法从废水中除去。文章综述了SRB的特点及它的生长条件,重点分析了利用SRB处理酸性矿山废水中存在的问题,如碳源、生物反应器的选择,并对生物处理酸性矿山废水的技术进行了展望。     

Adsorption Isotherms for Bleaching Soybean Oil with Activated Attapulgite

Activated attapulgite was characterized and used as bleaching clay (adsorbent) for soybean oil. Adsorption isotherms for bleaching soybean oil were determined to investigate the applicability of the Langmuir and Freundlich equations and to elucidate the adsorption characteristics of oil on activated attapulgite. The Freundlich model was found to provide a better fit with the experimental data than the Langmuir model. The larger Freundlich constant, K _F at higher temperature indicated more effective adsorption. The heat evolved for oil bleaching increased as the levels of activated attapulgite increased from 0.5 to 3%, due to the increase in adsorptive sites with increasing attapulgite levels as well as multilayer adsorption driven by van der Waals’ forces at smaller amounts of adsorbents. There are enough adsorptive sites with 3% attapulgite to adsorb the pigments associated with soybean oil bleaching. The amount of attapulgite has no effect on ΔH _a when it is >3%, and ΔH _a is about 32 kJ/mol.     

微生物在酸性矿井水形成过程中的作用

研究了山西某煤矿煤炭开采过程中不同阶段矿井水中微生物的种类、数量及其对矿井水酸化的作用。结果表明：煤层里的硫分和巷道中的氧气在煤层中的扩散是酸性矿井水产生的必备条件,同时,在矿井水不断酸化的过程中,微生物起到了至关重要的作用。前期起主要作用的是细菌如氧化亚铁硫杆菌、氧化硫硫杆菌及其它一些好氧硫杆菌等,后期某些具有氧化作用的霉菌如产黄青霉也起到了一定的作用,并由此推导出更为合理完善的酸性矿井水形成过程系列反应式。     

Removal of heavy metals by polysaccharide: a review

ABSTRACT

Industries produce large amounts of heavy metal waste that are hazardous to the environment. Thus, heavy metal ions such as nickel (II), lead (II), copper (II), cadmium (II), and zinc (II), must be removed from wastewater. One commonly employed method is biosorption, which is the adsorption of metal ions by biomaterials such as polysaccharides. In this review, polysaccharides are classified into four groups: polysaccharide homopolymers, polysaccharide blends, copolymers, and polysaccharide composites. Pristine natural polysaccharides like chitin, chitosan, cellulose, starch, and alginate which have multiple functional groups. Additional functionalization is introduced in the form of blending, grafting, or mixing with various nanomaterials having additional functional group to make it more efficient for heavy metal ion adsorption. Introduction of second component onto the main polymer chain not only introduce functionality but enhance mechanical strength which is one of the vital requirements for the recyclability of adsorbent. Longer the time adsorbent is reused more economical is the removal process of metal ions from wastewater. Heavy metal ions undergo various types of interaction like π-π interactions, dipole–dipole interaction, hydrogen bonding or van der walls force with homopolymer, copolymers, blends, or nanocomposite having anions or electron-rich group. Adsorption process is studied by adsorption kinetics and adsorption isotherms. This review represents the adsorption behavior of chitosan, cellulose, starch, alginate, and their derivatives.     

煤矿酸性矿坑排水的斑马鱼生物急性毒性研究

煤矿酸性矿坑排水具有低pH值,高金属离子含量的特征,要妥善处理,否则会污染环境,影响人们健康。以斑马鱼为实验生物,采用相加指数法,对煤矿酸性矿坑排水中普遍含有的Fe2（SO4）3、MnSO4、CuSO4进行了生物急性毒性实验。结果表明Fe2（SO4）3与MnSO4共存时的联合毒性为拮抗作用,而CuSO4与MnSO4,以及Fe2（SO4）3与CuSO4联合作用为协同作用。但当Fe2（SO4）3、MnSO4、CuSO43种毒物联合时其毒性为拮抗作用。除此之外,低pH值对重金属毒性有加强作用。     

锦界煤矿高浓度井下排水处理工程设计

锦界煤矿井下排水处理工程设计规模为4.32×104 m3/d,针对原水胶粒含量大、粒径小、比重轻等特点,矿井水处理采用预沉调节池+改良型机械搅拌澄清池+V型滤池的组合工艺,煤泥水处理采用直接离心脱水工艺,出水主要用作锦界煤矿周边电厂循环冷却用水及井下生产用水。介绍了该工程的工艺流程、设计参数及工艺特点,以期为同类煤矿井下排水处理工程的设计提供参考和借鉴。     

The role of sulfate as a competitive inhibitor of enzymatically‐mediated heavy metal uptake by Citrobacter sp: implications in the bioremediation of acid mine drainage water using biogenic phosphate precipitant

Heavy metals can be removed from solution via biocrystallization with enzymatically‐liberated inorganic phosphate, according to Michaelis–Menten kinetics, in free whole cells and cells immobilized within polyacrylamide gel in a flow‐through reactor. Sulfate is a competitive inhibitor of phosphate release and a predictive model was developed and shown to describe the effect of sulfate on the efficiency of phosphate release by flow‐through columns. The inhibitory effect was substantially less than anticipated in the case of metal removal by the columns. In the case of lanthanum removal metal removal efficiency was restored by increasing the substrate concentration in accordance with model predictions. In the case of uranyl ion its removal with an equivalent substrate supplement increased the activity by 20% over the initial value at a limiting flow rate. Since the initial loss in activity in the presence of 40 mmol dm⁻³ SO₄²⁻ (approximately twice the K_i value) was only approximately 20% with both metals this was considered to be a minor problem for bioprocess application. In confirmation, calculations made from a published ‘case history’ of application of the system to the bioremediation of acid mine drainage water (AMD) containing 0.22 mmol dm⁻³ of uranyl ion and 35 mmol dm⁻³ of SO showed that the benchscale model is a good representation of performance under actual load conditions. © 1999 Society of Chemical Industry     

Effects of physical parameters of a gravel bed on the activity of sulphate-reducing bacteria in the presence of acid mine drainage

The use of sulphate-reducing bacteria (SRB) in the passive treatment of acid mine drainage (AMD) requires the presence of a sediment, such as gravel bed, in which the bacteria can establish microenvironments conducive to their survival in the presence of oxygen and acidity. The characterization of relationships between the physical environment and SRB activity would be useful in the sizing of passive treatment systems using SRB. The effects of physical parameters of a gravel bed (i.e. void volume, total surface area of gravel, type of gravel) on SRB activity while in the presence of varying loads of fresh AMD was investigated. SRB activity was expressed as the proportion of sulphate removed after 7 days. The study was accomplished in a series of column reactors containing beds comprising different types and size classes of gravel. SRB were established in the beds and metal and sulphate removal were monitored. Quantifiable relationships were found to exist between SRB activity and the physical parameters of the bed. ©1997 SCI     

以污泥酸性发酵产物为碳源生物处理模拟酸性矿山废水的工艺特性

以污水处理厂污泥的酸性发酵产物为硫酸盐还原菌(SRB)的碳源,在厌氧膨胀颗粒污泥床(EGSB)反应器中,研究了生物处理模拟酸性矿山废水(AMD)的工艺特性及影响因素。试验结果表明,污水厂污泥的酸性发酵产物可作为SRB的合适碳源。常温(20℃)条件下,当AMD中SO24-浓度为3000 mg.L-1,pH值3.0,EGSB反应器中液体升流速度为5.0 m.h-1,水力停留时间HRT=13.8 h,碳源COD/SO24-比值取1.0左右,进水SO24-负荷为5.22 kg SO24-.m-3.d-1时,SRB的还原能力可达到3.32 kg SO24-.m-3.d-1,SRB的比还原能力为0.356 kg SO24-.(kg VSS)-1.d-1。AMD处理出水pH值可达6.0,SO24-还原率达到63.6%,COD去除率为45.1%,重金属Fe2+、Mn2+、Ni2+、Zn2+、Cu2+去除率均在89%以上。出水pH值和重金属离子浓度均满足排放标准。     

Removal of Heavy Metal Ions using New Chelating Material Containing N,O, and S Donor Sites

Abstract

A new chelating material (AT‐PHE‐HCHO) was synthesized by reacting 2‐aminothiazole‐phenol (AT‐PHE) azodye and formaldehyde (HCHO) in an alkaline medium. The materials were characterized by elemental analysis, FT‐IR and ¹H‐NMR spectroscopic studies. The chelating material was used for the adsorption of Cu(II), Zn(II), Mn(II), and Cr(III) from dilute aqueous solutions with variation of adsorption parameters. The adsorption was described quantitatively by fitting the equilibrium data to the Freundlich isotherm. The thermodynamic parameters ΔS and ΔH were calculated to be 86.02 J mol^?1 K^?1 and ?126.9 KJ mol^?1, respectively. The metal adsorption followed the sequence Cu(II)>Zn(II)～Cr(III)>Mn(II). The material was used for the removal of metal ions from synthetic as well as real samples.