矿物材料与环境污染治理—以粘土矿物和沸石为例

矿物的性能，矿区地质测试和吸附能力实验表明，粘土矿物和沸石等矿物材料对于Cr,Cd,Pb,Hg,As等有害元素具有很强的吸附能力，是理想的低成本吸附剂，在废水处理中可用来取代活性炭或离子交换树脂来去除重金属等有害元素。     

Testing the ability of bentonite-amended natural zeolite (clinoptinolite) to remove heavy metals from liquid waste

 The design of environmentally sound liquid waste containment structures has become a crucial task in engineering applications due to ever increasing groundwater contamination from such sites. Construction of such structures usually requires a bottom liner of low hydraulic conductivity as part of the design. In order to reduce the hazards associated with liquid wastes including landfill leachate, bentonite-amended natural zeolite is proposed as an alternative to conventional earthen liners. Among many contaminants associated with liquid wastes, heavy metals are the most dangerous ones. This paper deals with determining the ability of natural zeolite to remove heavy metals from aqueous waste. For this purpose, crushed natural zeolite (clinoptinolite) is amended with commercial powdered bentonite to yield a soil mixture low in permeability and high in ion-exchange capacity. Leachate from a conventional landfill is used as the percolation fluid. Concentrations of certain heavy metals in the effluent fluid percolated through the bentonite-zeolite mixture are compared with that of initial leachate. The conclusion is reached that certain metals are efficiently removed from the influent solution by the soil matrix whereas some ions do not show significant reduction in concentration. This is attributed to high hydraulic conductivity of the bentonite-zeolite mixture.     

Pb and Co removal from paint industries effluent using wood ash

The release of heavy metals into the environment is a worldwide major concern. Different studies have demonstrated that natural agents have a high removal capacity for divalent heavy metal ions. Wood ash is a natural adsorbent and, in comparison with others, has a very low price. In this study, the removal of heavy metals (Pb and Co) from Binalood paint industry (Kerman, Iran) effluent was investigated in batch condition. Pb and Co measurement in samples were done with atomic absorption equipment and test methods were adapted from standard methods for the examination of water and wastewater. The effect of pH and the amount of adsorbent was determined and different adsorption isotherms were also obtained. This study shows that the adsorption process follows the adsorption Langmuir isotherm. The amount of wood ash has a great role in the adsorption rate and adsorption rate increased as wood ash increased. In the study, the reactions reached equilibrium in 3 h contact time. The maximum Pb removal efficiency was 96.1 % at pH 2 with a contact time of 3 h and 100 g/L wood ash and the maximum Co removal efficiency was 99 % at pH 2 with a contact time of 3 h and 100 g/L wood ash. According to the results, wood ash is recommended as a low cost and available adsorbent to remove Pb and Co from municipal and industrial wastewaters.     

沸石的改性及其对水源水中氨氮去除的研究

以水源水为处理对象,通过对沸石进行酸、盐、高温改性和氨氮去除试验,考察沸石粒径、接触时间、温度等因素对氨氮去除的影响。结果表明,经盐(NaCl)改性的沸石对氨氮有较高的去除率,对于氨氮浓度为4.43mg/L的水源水,在粒径0.8～1.7mm、温度25℃的条件下,经15min接触,氨氮浓度可降至0.3mg/L,去除率可达93.2%。改性沸石对氨氮的去除机理是沸石表面(及内部孔隙)吸附作用和离子交换作用。对于普通自来水厂,只需将快滤池中常用的石英砂部分替换成改性沸石即可有效去除饮用水中的氨氮。经测算其投资仅增加33～39元/m3,运行费用基本不变。     

混凝沉淀-改性沸石方法联合处理锡铅锌多金属矿选矿废水初步研究

锡铅锌金属选矿过程中,重金属离子的溶出,使得选矿废水中重金属含量较高,需要处理才能达标排放。取原水pH值为8,Zn~(2+)为13.8mg/L,Cd~(2+)为0.07mg/L,采用混凝沉淀-改性沸石处理工艺流程处理,可使废水达到铅锌行业排放标准。在工程应用中,可使选矿废水达标排放,效果稳定,但沸石产泥量较大。     

Mathematical model for hydraulically aided electrokinetic remediation of aquifer and removal of nonanionic copper

One of the most cost-effective in situ technologies for soil and groundwater (i.e., aquifer) remediation is electrokinetic remediation. In electrokinetic remediation, electromigration due to electric field is combined with hydromigration due to hydraulic flow by purge water to remove pollutants from aquifers through the pore water. This study aims at investigating theoretically the role of electromigration (as active movement) of pollutants and the role of hydromigration (as passive movement) of pollutants in electrokinetic remediation, and making it clear that the control variables for electrokinetic remediation are the applied voltage and the hydraulic flow rate. These aims are pursued by construction of a mathematical model based on physico-chemical considerations and by model simulations of the electrokinetic remediation applied to the virtual aquifer polluted by heavy metals of copper sulfate. According to numerical simulations with the model: (1) heavy metal (nonanionic copper) is removed from the upstream anode region and accumulated in the downstream cathode region; (2) to carry away the heavy metal outside the aquifer (global removal), hydromigration by purge water flow is essential; and (3) electromigration contributes mainly to the redistribution of heavy metals within the aquifer (local removal and local accumulation).     

铜陵矿山酸性排水及固体废弃物中的重金属元素

在调查中国铜陵凤凰山铜矿和新桥硫铁矿两种不同类型矿山固体废弃物特征的基础上,研究了矿山尾矿和废石产生酸性排水的可能性及其差异以及矿山固体废弃物中重金属元素的赋存形式。结果表明,凤凰山铜矿的尾矿基本不产生矿山酸性排水,而新桥硫铁矿采矿废石产生矿山酸性排水,并且凤凰山铜矿的尾矿和新桥硫铁矿采矿废石中重金属元素的赋存形式也有差异,前者重金属Cu、Pb、Zn、Cd、As、Hg主要赋存于硅酸盐态中,而后者在还原态中有较高的含量,这反映了在地表条件下尾矿中大量重金属元素已经发生了迁移,而采矿废石已经开始氧化,且酸性排水的存在更有利于废石中重金属元素的迁移和扩散,进而导致矿区周围环境的污染。     

Potential use of faujasite–phillipsite and phillipsite–chabazite tuff in purification of treated effluent from domestic wastewater treatment plants

Characterization of zeolitic tuff from Jabal Hannoun (HN) and Mukawir (MR) was carried out to examine the ability of using low-cost natural materials in domestic wastewater treatment. The grain size between 0.3 and 1 mm (0.3–1 mm) of the HN and MR has the highest total zeolite grade (faujasite–phillipsite and phillipsite–chabazite) and suitable cation exchange capacity. They were used as fixed-bed ion exchangers and adsorbents. The zeolitic tuff efficiently removed the organic and nitrogen compounds, Pb and Zn from the effluent. One bed volume (1 BV) of the zeolitic tuff is capable to remove up to 95 % of total organic carbon form 500 BV of the effluent. The removal percent of total nitrogen by HN and MR is close to 95 and 90 %, respectively. The zeolitic tuff has an excellent efficiency to remove Pb and Zn from the effluent. 1 BV of HN completely cleans Zn and Pb from 680 and 730 BV of the effluent, respectively, whereas 1 BV of MR is able to clean completely Zn and Pb from 500 and 685 BV of the effluent, respectively. The greater performance of the HN compared with the MR may be explained by its higher zeolites grade and presence of faujasite.     

用赤泥去除酸性矿井水中重金属污染物的初步研究

利用碱性赤泥去除酸性矿井水中的污染物。通过比较不同的赤泥改性方法、赤泥改性温度、反应温度、反应时间及赤泥和矿井水不同的固液比等条件下水样中的pH值和Cu、Zn、As、Cd、Hg、Pb重金属元素的去除率，获得各污染物元素的最佳去除条件。为治理赤泥和酸性矿井水的污染开辟一条新的途径。     

Adsorption of copper and zinc onto natural clay in single and binary systems

Calcareous and smectitic clay samples from the Coniacian–Lower Campanian system, Tunisia, were used as adsorbents for the removal of copper and zinc from aqueous solutions in single and binary systems. Calcareous clay sample was treated with acetic acid to obtain carbonate-free sample that was also used for metals removal. The adsorption of metal ions onto natural clay was tested in a batch method by mixing 1 g/L of each sample with a metal ion solution of zinc (300 μmol/L) and/or copper 600 μmol/L under the operating pH of 6, and agitation speed of 200 rpm within the equilibrium time of 60 min at 25 °C for single and binary systems. Our results showed that natural clay samples were mainly composed of silica, alumina, iron, and magnesium oxides. Adsorption data showed that the studied clay samples removed substantial amounts of heavy metals in single and mixed systems. Initial solution pH and carbonates contents enhanced the removal capacities of the studied clay samples, confirming their strong influencing effects. Thermodynamic parameters indicated an endothermic adsorption for metals removal by calcareous clay, but exothermic process for the smectitic sample. These results suggest that the Late Cretaceous clays, Tunisia, can be effectively used as natural adsorbents for the removal of toxic heavy metals in aqueous systems.     

Acid Mine Drainage and Heavy Metal Pollution from Solid Waste in the Tongling Mines, China

Based on investigation of the characteristics of solid waste of two different mines, the Fenghuangshan copper mine and the Xinqiao pyrite mine in Tongling, Anhui province in central-east China, the possibility and the differences of acid mine drainage （AMD） of the railings and the waste rocks are discussed, and the modes of occurrence of heavy metal elements in the mine solid waste are also studied. The Fenghuangshan copper mine hardly produces AMD, whereas the Xinqiao pyrite mine does and there are also differences in the modes of occurrence of heavy metal elements in the railings. For the former, toxic heavy metals such as Cu, Pb, Zn, Cd, As and Hg exist mostly in the slag mode, as compared to the latter, where the deoxidization mode has a much higher content, indicating that large amounts minerals in the waste rocks have begun to oxidize at the earth surface. AMD is proved to promote the migration and spread of the heavy metals in mining waste rocks and lead to environmental pollution of the surroundings of the mine area.     

Effectiveness of Mg–Al-layered double hydroxide for heavy metal removal from mine wastewater and sludge volume reduction

Health hazards from heavy metal pollution in water systems are a global environmental problem. Of similar concern is sludge that results from wastewater treatment due to unsatisfactory sludge management technology. Therefore, the effectiveness of using Mg–Al-layered double hydroxide in the removal of heavy metals from mine wastewater was tested and compared with that of calcium hydroxide [Ca(OH)₂], which is a common treatment method for heavy metal removal. Initially, the mine wastewater contained cations of the heavy metals iron (Fe), zinc (Zn), copper (Cu), and lead (Pb). The Mg–Al-layered double hydroxides were able to remove 371, 7.2, 121, and 0.4 mg/L of these pollutants, respectively, using the co-precipitation method. The removal of these metals is most effective using 0.5 g Mg–Al-layered double hydroxide (Mg/Al molar ratio 4) and 20 min of shaking. Zn was removed by the formation of Zn(NO₃)(OH)·H₂O and Zn₅(NO₃)₂(OH)₈ when LDH, Mg/Al molar ratios of 4 and 2, respectively, were used. Similarly, Fe, Cu, and Pb were removed by the formation of Fe–Al-layered double hydroxide, Cu₂(OH)₃·NO₃ and Pb₄(OH)₄(NO₃)₄, respectively. While Ca(OH)₂ is also capable of reducing the heavy metal concentrations below the Japanese recommended values, this analysis shows that using 0.5 g Mg–Al-layered double hydroxide is a better treatment condition for mine wastewater, because it generates lower sludge volumes than 0.1 g of Ca(OH)₂. The measured sludge volume was 1.5 mL for Mg–Al-layered double hydroxide and 2.5 mL for Ca(OH)₂, a nearly twofold further reduction.     

Biological removal of cadmium by Alcaligenes eutrophus CH34

Some bacteria like the heavy metal resistant Alcaligenes eutrophos CH34strains are able to promote biomineralization, being the biologically induced crystallization of heavy metals. In the presence of heavy metals, this strain may create an alkaline environment in the periplasmic space and outer cell environment appropriate induction of heavy metals resistance mechanisms. In such an environment metal hydroxides are formed together with metal bicarbonates resulting from the carbonates production by the cell. Also metals bind to out cell membrane proteins and the metal hydroxides and bicarbonates precipitate around these nucleation foci inducing further metal crystallization. A pilot-plant was set up in which Alcaligenes eutrophus CH34 were inoculated and reproduced in a composite membrane, based on polysulfone. The membrane is casted on a polyester support. The biological membrane was in continuous contact with nutrients from inside and the other side was in contact with wastewater flow containing 120-mg/l cadmium. Nutrients are used for growth and reproduction of bacteria and for development of bacteria resistance agents against heavy metals. At the effluent side immobilized bacteria induce metal precipitation and metal crystals. A column, which was in continuous contact with treated effluent, was continuously filled with glass bends to which the metal crystals bind and grow. The efficiency for Cd removal was over 99 percent. Cd removal could be recovered from the recuperation column by acid treatment without damaging the bacteria.     

Water chemistry and heavy metal distribution in an AMD highly contaminated river

Environmental impacts of acid mine drainage (AMD) from Dexing Copper Mine, the largest open pit copper mine in Asia, on Le An River were well documented 10 years ago. However, ore production of the mine has increased fourfold and the contamination situation of the river now is unknown. Our studies indicated that heavy metal concentrations in riverwaters (dissolved), suspended solids (SS) and sediments all showed highly localized distribution patterns closely associated with two AMD-contaminated tributaries (Dawu River and Ji River) and are significantly different from the previous findings. Compared with the previous reports, most of the sampling sites in Le An River displayed lower contents of sediments of 2005 because several historical upstream and downstream heavy metal sources disappeared or became unimportant. The surprised decrease of copper contents in sediments at the mixing location with Dawu River was mainly due to dilution from the sufficient input of poor copper ore (<0.3%).     

Differentiating dilution and retention processes in mine effluent remediation within a natural wetland on the Zambian Copperbelt

The use of wetlands to treat mine effluent has grown in popularity over the past two decades, although the processes by which the natural systems function are often poorly understood. This field-scale investigation utilises daily data over a 9-month period in assessing the processes leading to the remediation of mine effluent within a natural wetland on the Zambian Copperbelt. The study differentiates effluent remediation through dilution from pollutant retention. Decreased wetland outflow concentrations of SO₄ and Na are due to dilution only, while Co (50%) and especially Cu (83%) are retained within the wetland. Retention was linked to adsorption onto new or primed surfaces during an initial period of effluent release into the system and to processes related to pH buffering to 7.5. The wetland’s acid buffering capacity was largely the result of carbonate-rich groundwater discharge into the wetland. Although this buffering capacity likely shows little seasonal fluctuation (20–80 kmol/day), the impact of acidic effluent input on the wetland itself probably varies markedly between seasons, owing to the temporal and spatial characteristics of discharge from the catchment’s aquifers. Assessment of other natural wetlands in the region indicated that some (circa 15%) showed similar catchment size, hydrochemical and hydrogeological characteristics as those of the New Dam wetland, likely demonstrating a similar effluent remediation potential as that described here.     

利用13X沸石分子筛净化含Pb~(2+)废水的实验研究

采用静态间歇法 ,实验研究了含Pb2 +废水的 pH值及吸附时间对 13X沸石分子筛吸附Pb2 +性能的影响 ,得出了最佳去除效果的优化条件为 :废水的 pH值接近中性 ,吸附时间 10min。通过吸附实验 ,确定了在Pb2 +初始浓度为 2 0mg/L的条件下 ,13X沸石对Pb2 +的吸附量为 2 1 4 2mg/g ,即每克沸石净化含Pb2 +废水的最大体积量约为 75 0mL。解析实验表明 ,加入沉淀剂 ,浓缩洗脱液中的Pb2 +即以PbS的形式生成沉淀 ,为回收金属铅提供了可能 ;13X沸石在循环使用 5次的条件下 ,对废水中Pb2 +的吸附率仍高达 98% ,重复使用性能良好。经处理后的净化水中Pb2 +的浓度小于 0 4mg/L ,显著低于国家废水排放标准GB8978 88的指标 ( 1 0mg/L)。 13X沸石对Pb2 +的主要吸附形式是离子交换和表面络合反应。     

High efficiency of heavy metal removal in mine water by limestone

The removal of Cd, Cu, Ni and Zn from dilute mine water by using several geological materials including pure limestone, sand, carbonaceous limestone and brecciated limestone was performed on a laboratory scale. The results showed that to add geological materials in combination with sodium carbonate injection would notably enhance the efficiency of heavy metal removal to varying degrees. Pure limestone was found the best one among the four materials mentioned above for removing heavy metals from mine water. The removal efficiencies of pure limestone when it is ground as fine as 30–60 meshes are 58.6% for Cd, 100% for Cu, 47.8% for Ni, and 36.8% for Zn at 20°C. The optimum pH is about 8.9 to 9.1. The mechanism of higher effective removal, perhaps, is primarily due to co-precipitation under the control of calcite-related pH value. According to this research, Na₂CO₃ injection manners, including slug dosing and drip-wise, seemed to have little impact on the efficiency of heavy metal removal.     

Adsorption of copper and zinc by oil shale

 Oil shale is able to remove appreciable amounts of copper and zinc ions from aqueous solutions. It was noted that an increase in the adsorbent concentration with constant copper or zinc concentration resulted in greater metal removal from solution. An increase in the copper or zinc concentration with a constant sorbent concentration resulted in higher metal loading per unit weight of sorbent. For both metals, copper and zinc, equilibrium was attained after 24-h contact time. Increase in the initial pH or temperature of the metal solution resulted in an increase in the metal uptake per unit weight of the sorbent. Freundlich isotherm model was found to be applicable for the experimental data of Cu²⁺ and Zn²⁺. The results showed that oil shale could be used for the adsorption of the Cu²⁺ and Zn²⁺ with higher affinity toward Zn²⁺ ions. Addition of sodium salt to the metal solution influenced copper removal positively, but inhibited zinc removal. Received: 3 January 2000 · Accepted: 27 June 2000     

Lead removal from wastewater using faujasite tuff

The Jordanian chabazite-phillipsite tuff and faujasite-phillipsite tuff have suitable mineralogical and technical properties that enable them to be used for ion-exchange processes. These include suitable grain size and total cation exchange capacity, acceptable zeolite content, good attrition resistance and high packed-bed density. The chabazite-phillipsite tuff (ZE1 and ZE2) has an excellent efficiency to remove Pb and an acceptable efficiency to remove Fe, Cu, Zn and Ni from effluent wastewater of a battery factory and other industries. The faujasite-phillipsite tuff (ZE3) is 6.97 times more efficient than the ZE1 and ZE2. A bed of ZE3 (1,000 kg) loaded in a 1.17-m³ column is capable of cleaning about 2,456 m³ of the effluent from the factory at a cost of US $200/ton. The wastewater is contaminated with 20 ppm Pb in the presence of competing ions including Ca (210 ppm), Na (1,950 ppm) and Fe (169 ppm). This quantity of wastewater is equivalent to 120 working days of effluent discharge from the factory at a flow rate of 20 m³/day.