德兴铜矿地区土壤的基本特征及其对重金属元素的吸附研究

本文首先分析了江西德兴铜矿区周围土壤的微量元素和矿物组成特征,结果显示该地区重金属元素富集,且表层土中重金属元素含量与粘土矿物相对含量变化具有较好的一致性。室内土柱淋滤实验结果表明,当总淋滤时间为451 h时,土壤对Pb²⁺的总吸附量为2 584.75 mg/kg,淋滤实验的前半期存在多种竞争吸附机制,后半期土壤对Pb²⁺的吸附基本达到动态平衡。淋滤后土壤矿物的相对质量分数发生了改变,粘土矿物有所减少。粘土矿物在不同土壤层对Pb²⁺的吸附能力也各异。     

Applications on agricultural and forest waste adsorbents for the removal of lead (II) from contaminated waters

At present, there is growing interest in using low cost, commercially available materials for the adsorption of heavy metals. The major advantages of adsorption technologies are its effectiveness in reducing the concentration of heavy metal ions to very low levels and the use of inexpensive adsorbent materials. In this review, agricultural and forest waste adsorbents were used to remove Pb²⁺ ions in wastewater treatment, and their technical feasibilities were reviewed in studies mainly from 2000 to 2010. They all were compared with each other by metal binding capacities, metal removal performances, sorbent dose, optimum pH, temperature, initial concentration and contact time. Although commercial activated carbon is widely used in wastewater treatment applications, it has high costs. The use of agricultural by-products as adsorbent material to purify heavy metal contaminated water has become increasingly popular through the past decade because they are less expensive, biodegradable, abundant and efficient. Instead of activated carbon, this study was focused on the inexpensive materials such as agricultural and forest waste. It was shown that these alternative adsorbents had sufficient binding capacity to remove Pb²⁺ ions from wastewater.     

Removal of Lead,Copper, Zinc and Cadmium from Water Using Phosphate Rock

Removal of Pb^2＋, Cu^2＋, Zn^2＋ and Cd^2＋ from aqueous solutions by sorption on a natural phosphate rock （FAP） was investigated. The effects of the contact time and initial metal concentration were examined in the batch method. The percentage sorption of heavy metals from solution ranges generally between 50% and 99%. The amount of sorbed metal ions follows the order Cu〉Pb〉Cd〉Zn. Heavy metal immobilization was attributed to both surface complexation of metal ions on the surface of FAP grains and partial dissolution and precipitation of a heavy metal-containing phosphate. The very low desorption ratio of heavy metals further supports the effectiveness of FAP as an alternative and low-cost material to remove toxic Pb^2＋, Cu^2＋, Zn^2＋ and Cd^2＋ from polluted waters.     

Toxic effect of Pb, Cd, Ni and Zn on Azolla filiculoides in the International Anzali Wetland

The limitation of plant growth in the polluted mediums can be used as a factor to determine of plant tolerance and the toxic effect of these mediums. In this work, the effect of Pb²⁺, Cd²⁺, Ni²⁺and Znsu2+ (individually) on Azolla filiculoides growth in the aqueous solution and using this method to water post treatment were studied. During 15 days the biomass the fresh Azolla with initial mass of 20 g was grown on the nutrient solution containing these metal ions, each in a concentration 4 mg/l. The presence of these ions, caused about 25%, 42%, 31% and 17% inhibition of biomass growth, respectively, in comparison to Azolla control weight which had not heavy metals. The water salinity of 1, 2 and 4 g. NaCl/l decreased the removal of these heavy metals about 4–7%, 20–24% and 40–55%, respectively. The addition of total dissolved solids (TDS) from 50 to 300 ppm. (as CaCO₃) into the samples of containing heavy metals increased Azolla growth, but decreased the control Azolla growth.     

Adsorption characteristics of phenol and heavy metals on biochar from <Emphasis Type="Italic">Hizikia fusiformis</Emphasis>

The objective of the present study is to evaluate the absorption efficacy of H. fusiformis biochar (HFB) for the removal of phenol and heavy metals from single and mixed solute systems of these species under different experimental conditions. The effects of contact time, pH change, initial phenol concentration, and heavy metal concentration on the adsorption capacity of HFB were investigated. The kinetics and equilibrium models of sorption of the components of the single and mixed solute systems on HFB were also studied. The experimental data were fitted to kinetic and equilibrium models. The batch experiments revealed that 360 min of contact time was sufficient to achieve equilibrium for the adsorption of both phenol and heavy metals. The adsorption of phenol and nickel by HFB followed the pseudo-second-order kinetic model, which was quite adequate for describing the adsorption mechanism. The equilibrium data for the adsorption of phenol and heavy metals fit well to the Langmuir model with regression coefficients of R ² > 0.819. The maximum Langmuir adsorption capacities were 10.39, 12.13, 22.25, 2.24, 2.89, and 22.03 mg/g for phenol, Ni²⁺, Zn²⁺, Cu²⁺, Pb²⁺, and Cd²⁺, respectively. Moreover, HFB exhibited optimal sorption under slightly acidic conditions at pH 6. The HFB used in the present study exhibited higher adsorption capacity for the removal of phenol and heavy metals from aqueous solutions compared to documented sorbents. These results demonstrate that HFB is potentially useful for alleviating the harmful effects of phenol and heavy metal in wastewater treatment systems.     

Experimental study of the selective adsorption of heavy metals onto clay minerals

The interaction between minerals and heavy metals has been a hot object of study in environmental science,mineralogy and soil science,Through the selective adsorption experiment of Ca-montomorillonite,illite and kaolinite to Cu2 ,Pb^2 ,Zn^2 ,Cd^2 ,and Cr^3 ions at certain conditions,it could be concluded that Cr^3 is most effectively sorbed by all the three minerals.Also,it can be found that Pb^2 shows a strong affinity for illite and kaolinite while cu^2 for montmorillonite .Based on the adsorption experiment at varying pH of solution,it can be found that the amount of heavy etals sorbed by minerals increases with increasing pH of the solution.     

Study on the purification property of pyrite and its spectra on the processing of metal-bearing wastewater

The purification property of pyrite was discussed by using in situ attenuated total reflection-Fourier transform infrared spectroscopy. Results showed that there might be dissolution–adsorption precipitation equilibrium of heavy metals on the surface of pyrite, which is dependent on the surface oxidation of pyrite and the neutralization reaction of carbonate within pyrite. If there was excessive carbonate within pyrite, the “dissolution” of metals would be less than that of the “adsorption precipitation,” making pyrite exhibit its purification property. Based on this property, pyrite was used to process simulated wastewater containing Pb²⁺, Hg²⁺, Cd²⁺, Cr(VI) and Cu²⁺. Results showed that the efficiencies of metal removal exceeded 96%. In addition, reflectance spectroscopy and absorption spectroscopy were also utilized to investigate the simulated metal-bearing wastewater treatment process. Analysis by diffused reflectance infrared Fourier transform spectroscopy confirmed that the superficial hydroxyl groups in pyrite reacted with metal ions during the wastewater treatment process. Reflectance spectroscopy in the visible region was used to characterize the variation in particle size and specific surface area of pyrite during the wastewater treatment process, which explained its increasing activity when reutilized. Further, analysis by absorption spectroscopy and X-ray photoelectron spectroscopy indicated that the process involved when using pyrite for the treatment of Cr(VI)-containing wastewater was an adsorption–precipitation process.     

The impacts of common ions on the adsorption of heavy metal

Researches on the impact of common ions onto sediments are of great importance for the study of the heavy metal adsorption mechanisms. Considering the surface sediments from the relatively clean reach in the Baotou section of the Yellow River as the adsorbent, this work presents the impacts of common ions (Na⁺, Mg²⁺, K⁺, Ca²⁺, Cl⁻, SO₄ ²⁻, and NH₄ ⁺) on heavy metals (Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺) adsorption. The experimental results reveal that the adsorptive capacities of the heavy metals are controlled by different adsorption mechanisms in different ion concentration ranges. With the increase of the ionic strength, the adsorption of the heavy metals increases for the compression of the electric double layer, whereas decreases for the decreasing of the ionic activities of the heavy metals. The competitive adsorption and complexations between the heavy metals and common ions are also important factors controlling the heavy metal adsorption. According to the experimental results and the real concentration of common ions in the Baotou section of the Yellow River, the increase of the concentrations of Na⁺, Mg²⁺, K⁺, and Ca²⁺ would cause the increase of Zn²⁺ adsorption and reduce the Zn pollution. The NH₄ ⁺ from the industrial discharge of the tributaries has a strong impact on the heavy metal adsorption.     

Heavy metal biosorption potential of a Malaysian Rhodophyte (<Emphasis Type="Italic">Eucheuma denticulatum</Emphasis>) from aqueous solutions

Biosorption is a promising technology for the removal of heavy metals from industrial wastes and effluents. In the present study, biosorption of Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺ onto the dried biomass of Eucheuma denticulatum (Rhodophyte) was investigated as a function of solution pH, contact time, temperature and initial metal ion concentration. The experimental data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The sorption isotherm data followed Langmuir and Freundlich models, and the maximum Langmuir monolayer biosorption capacity was found as 81.97, 66.23, 51.02 and 43.48 mg g^?1 for Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺, respectively. The sorption kinetic data followed pseudo-second-order and intraparticle diffusion models. Thermodynamic study revealed feasible, spontaneous and endothermic nature of the sorption process. Fourier transform infrared analysis showed the presence of amine, aliphatic, carboxylate, carboxyl, sulfonate and ether groups in the cell wall matrix involved in metal biosorption process. A total of nine error functions were applied in order to evaluate the best-fitting models. We strongly suggest the analysis of error functions for evaluating the fitness of the isotherm and kinetic models. The present work shows that E. denticulatum can be a promising low-cost biosorbent for removal of the experimental heavy metals from aqueous solutions. Further study is warranted to evaluate its potential for the removal of heavy metals from the real environment.     

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.     

Efficiency assessment of aerobic biological effluent treatment plant treating pharmaceutical effluents

The present paper undertakes a study of the physico-chemical properties and toxic heavy metals content in the untreated and treated pharmaceutical effluents in order to evaluate the working efficiency of industrial effluent treatment plants. The treatment efficiency achieved for various parameters was conductivity (79.94%), alkalinity (93.91%), hardness (87.70%), chloride (89.24%), cyanide (79.66%), phosphate (99.19%), total dissolved solids (85.89%), total suspended solids (96.87%), salinity (52.41%), dissolved oxygen (27.32%), biochemical oxygen demand (83.39%) and chemical oxygen demand (72.21%). The removal efficiency achieved for different heavy metals was Cu²⁺ (79.66%), Ni²⁺ (69.22%), Cr⁶⁺ (80.15%), Pb²⁺ (72.14%), Fe³⁺ (92.59%) and Zn²⁺ (90.61%). The level of biochemical oxygen demand (64 mg L^?1) in the treated effluents was above the limit of 30.0 mg L^?1, chemical oxygen demand level (208 mg L^?1) was close to a limit of 250 mg L^?1, while average Pb²⁺ concentration (0.10 mg L^?1) was on the borderline of maximum permissible limit of 0.10 mg L^?1 set by Central Pollution Control Board for safe discharge of industrial effluent in inland surface water. The average concentration of cyanide (0.01 mg L^?1) in the treated industrial effluent of our study is of great concern to the fisheries of freshwater ecosystem in which the effluents finally get discharged. Based on the results of the present study, it is concluded that the pollution level in the discharged pharmaceutical effluent is of the great concern requiring proper treatment and regular scientific monitoring so as to protect the environmental degradation of water resources and facilitate the propagation of the aquatic life.     

Biosorption characteristics of heavy metals (Ni2+, Zn2+, Cd2+, Pb2+) from aqueous solution by Hizikia fusiformis

Heavy metal ions (Pb²⁺, Cd²⁺, Ni²⁺, and Zn²⁺) were biosorbed by brown seaweed (Hizikia fusiformis), which was collected from Jeju Island of South Korea. The metal adsorption capacity of H. fusiformis improved significantly by washing with water or by base or acid treatments. The maximum sorption by NaOH-pretreated biomass was observed near a slightly acidic pH (pH 4?6) for Pb²⁺, Cd²⁺, Ni²⁺, and Zn²⁺. This result suggests that the treatment of H. fusiformis biomass with NaOH helped increase the functional forms of carboxylate ester units. Kinetic data showed that the biosorption occurred rapidly during the first 60 min, and most of the heavy metals were bound to the seaweed within 180 min. The maximum metal adsorption capacities assumed by a Langmuir model were on the order of Pb²⁺ > Cd²⁺ > Ni²⁺ > Zn²⁺. Equilibrium adsorption data for the heavy metal ions could fit well in the Langmuir model with regression coefficients R ² > 0.97.     

The long-term fate of Cu, Zn, and Pb adsorption complexes at the calcite surface: An X-ray absorption spectroscopy study

In this study, the speciation of Zn²⁺, Pb²⁺, and Cu²⁺ ions sorbed at the calcite surface was monitored during a 2.5-year reaction period, using extended X-ray absorption spectroscopy to characterize metal speciation on the molecular scale. Experiments were performed using pre-equilibrated calcite-water suspensions of pH 8.3, at metal concentrations below the solubility of metal hydroxide and carbonate precipitates, and at constant metal surface loadings. The EXAFS results indicate that all three metals remained coordinated at the calcite surface as inner-sphere adsorption complexes during the 2.5-year ageing period, with no evidence to suggest slow formation of dilute metal-calcite solid solutions under the reaction conditions employed. All three divalent metals were found to form non-octahedral complexes upon coordination to the calcite surface, with Zn²⁺ adsorbing as a tetrahedral complex, Cu²⁺ as a Jahn-Teller distorted octahedral complex, and Pb²⁺ coordinating as a trigonal- or square-pyramidal surface complex. The non-octahedral configurations of these surface complexes may have hindered metal transfer from the calcite surface into the bulk, where Ca²⁺ is in octahedral coordination with respect to first-shell O. The use of pre-equilibrated calcite suspensions, with no net calcite dissolution or precipitation, likely prevented metal incorporation into the lattice as a result of surface recrystallization. The results from this study imply that ageing alone does not increase the stability of Zn²⁺, Pb²⁺, and Cu²⁺ partitioning to calcite if equilibrium with the solution is maintained during reaction; under these conditions, these metals are likely to remain available for exchange even after extended sorption times.     

A comparison of organic wastes as bioadsorbents of heavy metal cations in aqueous solution and their capacity for desorption and regeneration

The adsorption capacity of seven organic wastes/by-products (slash pine, red gum and western cypress bark, composted green waste, prawn exoskeletons, spent brewery yeast and mill mud from a sugar mill) for transition metals were determined at two metal concentrations (10 and 100 mg L⁻¹) and three equilibrium pH values (4.0, 6.0 and 8.0) in batch adsorption experiments. All tested materials indicate a positive affinity to adsorb metal cations from aqueous solution and spent yeast was the least effective. Adsorption generally increased with increasing pH and the order of selectivity of metals was: Cr³⁺ > Cu²⁺ > Pb²⁺ > Zn²⁺ ≥ Cd²⁺. For pine bark, compost, spent yeast and prawn shell, quantities of previously adsorbed Pb and Cd desorbed in 0.01 M NaNO₃ electrolyte were negligible. However, 0.01 M HNO₃, and more particularly 0.10 and 0.50 M HNO₃ were effective at removing both adsorbed Pb and Cd. Using 0.10 M HNO₃ as the regenerating agent, pine bark and compost maintained their Pb and Cd adsorption capacity over eight successive adsorption/regeneration cycles. For mill mud and prawn shell, there was a pronounced decrease in adsorption capacity after only one regeneration cycle. A subsidiary experiment confirmed that acid pre-treatment of the latter two materials appreciably reduced their Pb and Cd adsorption capacity. This was ascribed to the metal adsorption capacity of prawn shell and mill mud being partially attributable to their significant CaCO₃ content and acid treatment induces dissolution of the CaCO₃. It was shown that in relation to both adsorption capacity and desorption/regeneration capability, composted green waste showed the greatest potential.     

腐植酸改性强化磁铁矿吸附水体中铅镉的实验研究

磁铁矿是一种绿色廉价的矿物材料,对水体中重金属离子具有良好的吸附性,但吸附容量低,选择性差,易团聚,通过改性可以克服该缺点并提高其吸附性能。本文以腐植酸为改性剂,采用常温水相反应制备了腐植酸改性磁铁矿吸附材料。通过傅里叶红外光谱(FTIR)、扫描电镜(SEM)和X射线光电子能谱(XPS)表征研究其表面形貌和微观结构。采用静态平衡实验考察了pH、吸附时间等因素对铅、镉吸附性能的影响,探讨了吸附动力学规律,拟合了吸附等温线。结果表明:腐植酸上的羧基、羟基被成功地接枝到了磁铁矿表面。在室温下,溶液初始pH对Pb~(2+)的吸附率几乎无影响,对Cd~(2+)的影响较大,当pH=7时,Pb~(2+)和Cd~(2+)吸附率均达到了95%。对初始质量浓度为10mg/L的Pb~(2+)、Cd~(2+)最佳吸附平衡时间为360min,吸附过程符合准二级动力学方程。吸附等温线实验得到的竞争吸附顺序为Pb~(2+)Cd~(2+),由Langmuir等温吸附模型得到Pb~(2+)、Cd~(2+)饱和吸附容量分别为39.27mg/g、28.95mg/g,显著大于磁铁矿的饱和吸附容量,表明磁铁矿经腐植酸改性后增强了对水中铅镉的吸附能力。     

Lead coprecipitation with iron oxyhydroxide nano-particles

Pb²⁺ and Fe³⁺ coprecipitation was studied with sorption edge measurements, desorption experiments, sorbent aging, High Resolution Transmission and Analytical Electron Microscopy (HR TEM-AEM), and geochemical modeling. Companion adsorption experiments were also conducted for comparison. The macroscopic chemical and near atomic scale HRTEM data supplemented our molecule scale analysis with EXAFS (Kelly et al., 2008). Coprecipitation of Pb²⁺ with ferric oxyhydroxides occurred at ∼pH 4 and is more efficient than adsorption in removing Pb²⁺ from aqueous solutions at similar sorbate/sorbent ratios and pH. X-ray Diffraction (XRD) shows peaks of lepidocrocite and two additional broad peaks similar to fine particles of 2-line ferrihydrite (2LFh). HRTEM of the Pb-Fe coprecipitates shows a mixture of 2-6 nm diameter spheres and 8-20 by 200-300 nm needles, both uniformly distributed with Pb²⁺. Geochemical modeling shows that surface complexation models fit the experimental data of low Pb:Fe ratios when a high site density is used. Desorption experiments show that more Pb²⁺ was released from loaded sorbents collected from adsorption experiments than from Pb to Fe coprecipitates at dilute EDTA concentrations. Desorbed Pb²⁺ versus dissolved Fe³⁺ data show a linear relationship for coprecipitation (CPT) desorption experiments but a parabolic relationship for adsorption (ADS) experiments.Based on these results, we hypothesize that Pb²⁺ was first adsorbed onto the nanometer-sized, metastable, iron oxyhydroxide polymers of 2LFh with domain size of 2-3 nm. As these nano-particles assembled into larger particles, some Pb²⁺ was trapped in the iron oxyhydroxide structure and re-arranged to form solid solutions. Therefore, the CPT contact method produced more efficient removal of Pb²⁺ than the adsorption contact method, and Pb²⁺ bound in CPT solids represent a more stable sequestration of Pb²⁺ in the environment than Pb²⁺ adsorbed on iron oxyhydroxide surfaces.     

Heavy metals removal from synthetic wastewater by a novel nano-size composite adsorbent

The effects of varying operating conditions on metals removal from aqueous solution using a novel nano-size composite adsorbent are reported in this paper. Characterization of the composite adsorbent material showed successful production of carbon nanotubes on granular activated carbon using 1 % nickel as catalyst. In the laboratory adsorption experiment, initial mixed metals concentration of 2.0 mg/L Cu²⁺, 1.5 mg/L Pb²⁺ and 0.8 mg/L Ni²⁺ were synthesized based on metals concentration from samples collected from a semiconductor industry effluent. The effects of operation conditions on metals removal using composite adsorbent were investigated. Experimental conditions resulting in optimal metals adsorption were observed at pH 5, 1 g/L dosage and 60 min contact time. It was noted that the percentage of metals removal at the equilibrium condition varied for each metal, with lead recording 99 %, copper 61 % and nickel 20 %, giving metal affinity trend of Pb²⁺ > Cu²⁺ > Ni²⁺ on the adsorbent. Langmuir’s adsorption isotherm model gave a higher R² value of 0.93, 0.89 and 0.986 for copper, nickel and lead, respectively, over that of Freundlich model during the adsorption process of the three metals in matrix solution.     

Assessment of raw clays from Maghnia (Algeria) for their use in the removal of Pb<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> ions from industrial liquid wastes: a case study of wastewater treatment

Homogenized samples of raw clays resulting from two (2) different lots of natural clays from Maghnia (Algeria) have been assessed for their potential use in the removal of Pb²⁺ and Zn²⁺ ions from industrial liquid wastes (LW). Raw and acid-activated samples have been characterized by powder X-ray diffraction, FT-IR spectroscopy, electron microscopy (SEM), and X-ray fluorescence (XRF) and used as adsorbents for the removal of Pb²⁺ and Zn²⁺ ions from aqueous system using adsorption method under different conditions. The effect of factors including contact time, pH, and dosage on the adsorption properties of Pb²⁺ and Zn²⁺ ions onto clays was investigated at 25 °C. The obtained results revealed that the removal percentages of Pb²⁺ and Zn²⁺ ions, from both aqueous solution (AS) and LW, were varying between 90 and 98% for 40 min and optimal pH values ranged from 5 to 6 for Pb²⁺ and Zn²⁺ ions, respectively. The kinetics of both Pb²⁺ and Zn²⁺ ion adsorption fitted well with the pseudo-second-order model. Langmuir, Freundlich, and Temkin adsorption isotherms were used, and their constants were evaluated. The values of thermodynamic parameters, ΔH°, ΔS°, and ΔG° indicated that the adsorption of Pb²⁺ and Zn²⁺ ions was spontaneous and exothermic process in nature. The adsorption and desorption isotherms indicated that Pb²⁺ and Zn²⁺ adsorption to raw clays was reversible. The experimental results obtained showed that the raw clays from Maghnia (Algeria) had a great potential for removing Pb²⁺ and Zn²⁺ ions from industrial liquid wastes using adsorption method.     

金川铜镍硫化物精矿中有价金属分离实验研究

本文以金川铜镍硫化物精矿为研究对象,对比研究了A.f.菌浸出与硫酸酸溶浸出对铜镍硫化物精矿中有价金属Co、Ni和Cu的提取效果。为了进一步优化硫化物精矿中有价金属Co、Ni和Cu浸出效果,考察了微生物-硫酸浸出与硫酸-微生物浸出对精矿中Co、Ni和Cu提取的影响。结果表明:Co2+、Ni2+、Cu2+微生物-硫酸浸出率可分别达到85.05%、98.32%和95.31%。微生物-硫酸浸出加速了硫化物矿物的溶解,促进了硫化物矿物中有价金属Co、Ni、Cu的浸出,大大提高了有价金属Co2+、Ni2+、Cu2+的浸出率。     

Comparative evaluation of EDTA, pyridine and acetic acid for the assessment of available heavy metals from domestic and industrial sludges

Various sludge samples from different domestic and industrial wastewater treatment plants were analyzed by Flame Atomic Absorption Spectrometry (FAAS) to evaluate their total and available contents of heavy metals (Pb, Hg, Cd and Zn). The EDTA, pyridine and acetic acid single extraction techniques were applied to these samples with the objective of studying the leaching behavior of the metals in different sludges and also to predict their possible mobility when these wastes are disposed on the environment and landfills. In EDTA, higher extraction efficiency was observed for major part of the elements studied in the industrial sludges except for Hg and Cd, which were also considerably released from domestic sludges. Acetic acid and pyridine gave a better extraction efficiency for Zn in industrial sludge than EDTA. Moreover, the results of total digestions were compared, for total metal contents, with those obtained using pseudototal digestion procedure and a good correlation (r² = 0.95) was found between the two methods of digestion.