Continuous-flow fractionation of trace metals in environmental solids using rotating coiled columns. Some kinetic aspects and applicability of three-step BCR leaching schemes

The applicability of the three-step BCR leaching scheme to the continuous-flow fractionation of trace metals (TM) using rotating coiled columns (RCC) has been investigated taking soil and sediment reference samples (SRM-2710, CRM-601, BCR-701) as examples. A particulate sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while different eluents, used according to the original and optimised BCR protocols, were continuously pumped through. The whole procedure required 3-4 h instead of at least 50 h needed for the traditional sequential extraction. It has been shown that in comparison with batch sequential extraction procedures (SEP), the recoveries of Cd, Zn, Cu, and Pb at the first stage (most mobile and potentially dangerous acid soluble forms) are somewhat higher, if a dynamic extraction in RCC is used. Nevertheless, the distribution patterns for TM in the first two leachable fractions (acid soluble and reducible forms) are similar in most cases. Since no heating is used in RCC, the recoveries of TM at the third stage (when hydrogen peroxide is applied to oxidize the organic matter) may be incomplete and matrix-dependent. The effect of eluent volume and flow rate on the recovery of TM in different forms has been investigated. It has been shown that the kinetics of heavy metal leaching vary significantly with samples. Hence, investigating the elution profiles can provide additional important information for risk assessment of TM mobilization.     

Accelerated fractionation of heavy metals in contaminated soils and sediments using rotating coiled columns

A new approach to performing an accelerated sequential extraction of trace elements from solid samples has been proposed. It has been shown that rotating coiled columns (RCC) earlier used in counter-current chromatography can be successfully applied to the dynamic leaching of heavy metals from soils and sediments. A solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while different eluents (aqueous solutions of complexing reagents, mineral salts and acids) were continuously pumped through. The procedure developed is time saving and requires only 4-5 h instead of the several days needed for traditional sequential extraction (TSE), complete automation being possible. Losses of solid sample are minimal. In most cases the recoveries of readily bioavailable and leachable forms of Pb, Zn, and Cd are higher, if a dynamic extraction in RCC is used. Since naturally occurring processes are always dynamic, continuous extraction in RCC may help to estimate the contents of leachable forms and their potential risk for the environment more correctly than batch TSE. The Kersten-Foerstner and McLaren-Crawford leaching schemes have been compared, the former has been found to be preferable.     

Distribution and fractionation of cadmium, copper, lead, nickel, and zinc in a calcareous sandy soil receiving municipal solid waste

This study was conducted to evaluate the degree of mobility and fractionation of cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn) after the addition of municipal solid sewage sludge (MSS) in a sandy calcareous soil. Treatments were (1) soil application of MSS, (2) soil application of enriched municipal solid waste compost (EMSS), and (3) control soil. The MSS application represented a dose of 200 Mg dry weight per hectare. Soil columns were incubated at room temperature for 15 days and irrigated daily with deionized water to make a total of 505 mm. At the end of leaching experiments, soil samples from each column were divided into 14 layers, each being 1 cm down to 10 and 2.5 cm below that and analyzed for diethylenetriaminepentaacetic acid (DTPA)-extractable Cd, Cu, Pb, Ni, and Zn. The fractionation of the heavy metals in the top five layers of the surface soil samples was investigated by the sequential extraction method. All soil layers of the columns receiving MSS and EMSS had significantly higher concentrations of DTPA-extractable heavy metals than control soil. The maximum concentration of heavy metals in treated soil was in the surface layer and declined significantly with depth. Sequential extraction results showed that in the treated soil, a major proportion of Cd, Pb, and Ni was associated with organic matter (OM) and exchangeable (EXCH) fractions, and a major proportion of Cu and Zn was associated with residual (RES) and OM fractions. Based on relative percent, Pb, Cd, and Ni in the EXCH fraction was higher than Cu and Zn in soil leached with MSS and EMSS, suggesting that application of this MSS to a sandy calcareous soil, at the loading rate used here, may pose a risk in terms of groundwater contamination with Pb, Cd, and Ni.     

Design of a Leaching Test Framework for Coal Fly Ash Accounting for Environmental Conditions

Fly ash from coal combustion contains trace elements which, on disposal or utilisation, may leach out, and therefore be a potential environmental hazard. Environmental conditions have a great impact on the mobility of fly ash constituents as well as the physical and chemical properties of the fly ash. Existing standard leaching methods have been shown to be inadequate by not representing possible disposal or utilisation scenarios. These tests are often criticised on the grounds that the results estimated are not reliable as they are not able to be extrapolated to the application scenario. In order to simulate leaching behaviour of fly ash in different environmental conditions and to reduce deviation between measurements in the fields and the laboratories, it is vital to study sensitivity of the fly ash constituents of interest to major factors controlling leachability. pH, liquid-to-solid ratio, leaching time, leachant type and redox potential are parameters affecting stability of elements in the fly ash. Sensitivity of trace elements to pH and liquid to solid ratio (as two major overriding factors) has been examined. Elements have been classified on the basis of their leaching behaviour under different conditions. Results from this study have been used to identify leaching mechanisms. Also the fly ash has been examined under different standard batch leaching tests in order to evaluate and to compare these tests. A Leaching Test Framework has been devised for assessing the stability of trace elements from fly ashes in different environments. This Framework assists in designing more realistic batch leaching tests appropriate to field conditions and can support the development of regulations and protocols for the management and disposal of coal combustion by-products or other solid wastes of environmental concern.     

Aluminium contamination via assisted leaching from metallic aluminium utensils at neutral pH

Fluoride ion in trace concentrations is found to leach metallic aluminium from utensils even at neutral pH, releasing aluminium hydroxide which is readily soluble in dilute acids. The levels of leaching at different F^- concentrations are given and compared with leaching levels with equivalent concentrations of Cl^-. It is suggested that consumption of water boiled in aluminium utensils may contribute to cumulative aluminium toxicity.     

The Impact of Scrubber Sludge on Ground Water Quality at an Abandoned Mine Site

A sulfate-rich flue gas desulfurization scrubber sludge was used as a substitute backfill material in reclamation of an abandoned coal strip mine. The site was surrounded by monitor wells and the material was characterized for leaching behavior using open column experiments. A drain was placed directly beneath the 45 000 ton fill to enable sampling before dilution or attenuation. The column studies indicated that the scrubber sludge would adsorb manganese, iron, aluminium, cobalt, nickel, thallium and zinc contaminants from the water. Changes in pH appear inadequate to explain the removal by precipitation. The groundwater cleaning phenomenon has been confirmed on a field scale by the drain samples. Boron and molybdenum leach from the fly ash was used to fix the scrubber sludge and serve as marker elements enabling calibration of the dispersivity in computer models of the groundwater system at the site. The leachate front appears to be diluted by a factor of 8 : 1 within the first 15 meters. Since boron and molybdenum release are associated only with the first flush, environmental impacts will be minimal. Columns appear to create a time compression effect on the duration of leaching phenomenon. The effect for this site appears to be at least 5 : 1. The columns were effective in predicting which elements would leach or adsorb in the field and in predicting the actual source concentrations. Other shake tests such as the TCLP and the ASTM shake test were found to be less effective at predicting which elements would leach and were not helpful in predicting field concentrations.     

Effects of leachant temperature and pH on leachability of metals from fly ash. A case study: Can thermal power plant, province of Canakkale, Turkey

Lignite powered electric generation plants result in increasing environmental problems associated with gaseous emissions and the disposal of ash residues. Especially, low quality coals with high ash content cause enormous quantities of both gaseous and solid fly ash emissions. The main problem is related to the disposal of fly ash, which, in many cases, contains heavy metals. It is known that toxic trace metals may leach when fly ash is in contact with water. In this study, fly ash samples obtained from the thermal power plant in the town of Can in Turkey were investigated for leachability of metals under different acidic and temperature conditions. The experimental results show that a decrease in pH of the leachant favors the extraction of metal ions from fly ash. A significant increase in the extraction of arsenic, cadmium, chromium, zinc, lead, mercury, and selenium ions from the ash is attributed to the instability of the mineral phases. These heavy metals concentrations increase with respect to increasing acidic conditions and temperature. Peak concentrations, in general, were found at around 30°C.     

Speciation of Trace Metals in Coastal Sediments of El-Mex Bay South Mediterranean Sea–West of Alexandria (Egypt)

Sediments of El-Mex Bay estuary on the southern Mediterranean Sea have been analyzed for trace metals after sediment fractionation by sequential leaching. A sequential extraction procedure was applied to identify forms of Mn, Cu, Cd, Cr, Zn and Fe. The five steps of the sequential extraction procedure partitioned metals into: CH₃COONH₄ extractable (F1); NaOAC carbonate extractable (F2); NH₂OH.HCl/CH₃COOH reducible extractable (F3); H₂O₂–HNO₃ organic extractable (F4) and NHO₃/HClO₄/HF acid soluble residue (F5). Extracted concentrations of trace metals analyzed after all five steps, were found to be (μg/g) for Mn: 1930.2, Cu: 165.3, Cd: 60.9, Cr: 386.3, Zn: 2351.3 and Fe: 10895. Most of elements were found in reducible fraction except Fe found in acid soluble residue, characterizing stable compounds in sediments. Labile (non-residual) fractions of trace elements (sum of the first four fractions) were analyzed because they are more bioavailable than the residual amount. Correlation analysis was used to understand and visualize the associations between the labile fractions of trace metals and certain forms, since Fe-and Mn-oxides play an important role in trace metals sorption within aquatic systems, especially within El-Mex Bay sediments that characterized by varying metal bioavailability.     

Seasonal and spatial distribution of trace elements in the water and sediments of the Tsurumi River in Japan

The Tsurumi, a class-one Japanese river, has a significant metal loading originating from urban environment. Water and sediment samples were collected from 20 sites in winter and summer, 2009 and were analyzed to determine and compare the extent of different trace element enrichment. A widely used five-step sequential extraction procedure was also employed for the fractionation of the trace elements. Concentrations of zinc, copper, lead, chromium, and cadmium were three to four times higher than that of reference values and downstream sediments are much more polluted than the upstream sites. Geochemical partitioning results suggest that the potential trace metal mobility in aquatic environment was in the order of: cadmium > zinc > lead > copper > cobalt > chromium > molybdenum > nickel. About 80.2% zinc, 77.9% molybdenum, 75.3% cobalt, 63.7% lead, 60.9% copper, 55.1% chromium, and 39.8% nickel in the sediment were contributed anthropogenically. According to intensity of pollution, Tsurumi river sediments are moderately to heavily contaminated by zinc, lead, and cobalt. Enrichment factor values demonstrated that zinc, lead, and molybdenum have minor enrichment in both the season. The pollution load index (PLI) has been used to access the pollution load of different sampling sites. The area load index and average PLI values of the river were 7.77 and 4.93 in winter and 7.72 and 4.89 in summer, respectively. If the magnitude of pollution with trace metal in the river system increases continuously, it may have a severe impact on the river’s aquatic ecology.     

Chemical sequential extraction for metal partitioning in environmental solid samples

A comprehensive review of the sequential extraction schemes for metal fractionation in environmental samples (ie., sediment, soil, sewage sludge, fly ash, etc.) is presented. The review contains more than 400 references and covers principally the literature published over the last decade. The use of each reagent involved in these schemes is looked at critically, and guidelines for their selectivity and extraction capacity are given. The operational character of these schemes is emphasised. Topics such as comparability between sequential extraction schemes of widespread use, harmonisation, acceleration, validation, etc. are addressed and future developments outlined.     

Comparison of three sequential extraction procedures for partitioning of heavy metals in car park dusts

The aim of this study was to elucidate the amount of metal released at each step by using different extractants in three sequential extraction schemes for the partitioning of metal contents of car park deposited dust samples. For this purpose, three different sequential extraction procedures (SEP) were employed for the metal fractionation in car park dust samples collected from the campus of Erciyes University, Kayseri, Turkey. While two of the sequential extraction procedures contain five steps the other, namely the BCR sequential extraction scheme, has three steps. The first two methods fractionate metals to be exchangeable, bound to carbonates, bound to Mn oxides, bound to Fe oxides and bound to organic matter, and the BCR protocol fractionates the metals as acid soluble and exchangeable, reducible, and oxidisable. Determination of the metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was performed by flame atomic absorption spectrometry (FAAS). The results obtained by the three methods were compared and showed that the amount of metal released at each step of the leaching procedure depended both on the type of reagents used and the sequence in which they were applied. The most mobile elements were Cd, Pb and Zn which are metals potentially toxic to the environment and are also known to originate from traffic. The calculated enrichment factors for Cd and Pb were substantially high (73.5-187 and 18.4-27.5, respectively) and somewhat lower for Zn (5.1-6.8). These results confirm that they are important metal pollutants for car parks. Detection limits and recoveries were found in the range of 0.01-1.39 microg ml(-1) and 68-126%, respectively, for the metals studied and the three sequential extraction procedures.     

Leaching Characteristics of Fly Ash from Thermal Power Plants of Soma and Tunçbilek, Turkey

Use of lignite in power generation has led to increasing environmental problems associated not only with gaseous emissions but also with the disposal of ash residues. In particular, use of low quality coal with high ash content results in huge quantities of fly ash to be disposed of. The main problem related to fly ash disposal is the heavy metal content of the residue. In this regard, experimental results of numerous studies indicate that toxic trace metals may leach when fly ash contacts water. In this study, fly ash samples obtained from thermal power plants, namely Soma and Tunçbilek, located at the west part of Turkey, were subjected to toxicity tests such as European Committee for standardization (CEN) and toxicity characteristic leaching (TCLP) procedures of the U.S. Environmental Protection Agency (U.S. EPA). The geochemical composition of the tested ash samples from the power plant show variations depending on the coal burned in the plants. Furthermore, the CEN and TCLP extraction results showed variations such that the ash samples were classified as `toxic waste' based on TCLP result whereas they were classified as `non-toxic' wastes based on CEN results, indicating test results are pH dependent.     

Conventional, microwave, and ultrasound sequential extractions for the fractionation of metals in sediments within the Petrochemical Industry, Serbia

In this paper, the main objective was fractionation of Cd, Cu, Ni, Pb, Zn, Ca, Fe, and K in certificate material and sediment samples gathered from and around the Petrochemical Industry using the conventional, microwave and ultrasonic sequential extraction. Microwave oven and ultrasound bath were used as an energy source for achieving faster extraction. Additional heating and boiling of samples were avoided by using lower power and shorter time for microwave and ultrasound extraction. Precision and accuracy of procedure were evaluated by using certificate material (BCR701). Acceptable accuracy of metals (87.0–111.3 %) was achieved for all three-step sequential of conventional extraction protocol. An accuracy of the fourth step has been verified with two certificate materials: BCR143R and 146R. The range of total extracted metal concentrations from sediments was similar for all three extraction techniques. A significant high percentage of Cd, Cu, and Zn were obtained after extraction of the exchangeable and acid soluble sediment fraction. Principal component analysis of values obtained after determination of risk assessment code using conventional and ultrasound sequential extraction show similarity of these values. Accuracy, recovery, and risk assessment code values imply that ultrasound sequential extraction is a more suitable, accelerated sequential extraction procedure (30 min per extraction step) than microwave extraction in applied conditions.     

A study of the elemental leachability and retention capability of compost

In this work a comparison is made between the different approaches that can be taken to evaluate the mobility of elements in compost. The practical consequences of the results obtained are also discussed in terms of methods for cleaning up compost and using compost in environmental remediation. The mobility of potentially toxic elements in compost is evaluated by leaching with four selected eluents, i.e. diluted sulfuric acid, oxalate, citrate and EDTA. In contrast to the chelating agents, diluted sulfuric acid was found to generally have a low leaching capability for removal of heavy metals from compost. This implies that the risk of heavy metal leaching caused by natural rainfall is likely to be low. The results obtained in the leaching experiment were compared with previous results obtained from sequential fractionation. This comparison confirmed that both methods gave similar results for predicting the lability of elements in compost. A non-linear regression analysis of the leaching curves was also conducted. The leaching curves for elements with high lability could be fitted with a two components model. The labile components identified by the kinetic model are approximately in accordance with the fractions obtained from the first step of the sequential extraction method. The kinetic speciation method is shown to be a relatively rapid and simple procedure for compost which gives more information about element lability than simple leaching experiments. The leaching reagents used in this work were not effective enough to be used for cleaning up compost with a high metal content. Compost was however shown to have a high affinity for heavy metals, with the order of affinity of metal for the compost being very similar to that seen for humic acid. Compost may therefore prove to be a good remediation material for metal contaminated waste.     

Fractionation of eleven elements by chemical bonding from airborne particulate matter collected in an industrial city in Argentina

A four-step chemical sequential extraction procedure was used to evaluate the distribution of Al, As, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn in airborne particulate matter collected on glass fibre filters using a high-volume sampler. Two sets of samples were collected in 2001 (winter and summer campaigns) in representative zones of an industrial city of Argentina. The leaching scheme was applied to PM-10 particles and consisted in extracting the elements in four fractions, namely soluble and exchangeable elements; carbonates, oxides and reducible elements; bound to organic matter and sulfidic metals; and residual elements. Metals and metalloids at microg g(-1) level were determined in each fraction by inductively coupled plasma optical emission spectrometry (ICP OES). Analyte concentration varied from 14 microg g(-1) (equivalent to 1.0 ng m(-3)) for As to 11.8 mg g(-1) (equivalent to 2,089 ng m(-3)) for Al. Seven elements, namely Al, Cr, Fe, Mn, Pb, Ti and Zn showed similar distributions in both seasons while As was distributed in a significantly different manner in each season. The results exhibited low As contents in the first and second fractions that could be associated with routine coal combustion and a high content in the third and fourth fractions of the summer samples that could be linked to the use of pesticides. Aluminium, As, Cu, Mn, Ni, Ti, V and Zn were found in different percentages in the more bioavailable aqueous fraction with As, Mn, V and Zn exhibiting solubilities greater than 1% while Cr and Pb being insoluble. The content of Al, Cr, Cu, Fe, Ni, Pb, and Zn in the residual fraction was, in average, higher than 50%. A comparative assessment of the use of the underlying information available from fractionation studies compared to that obtained from total element content was done for Fe and Mn. It showed that the results obtained using chemical sequential extraction procedures allowed further discrimination of the potential air pollution sources.     

Pollution and potential mobility of Cd, Ni and Pb in the sediments of a wastewater-receiving river in Hanoi, Vietnam

Large quantities of untreated industrial and domestic wastewater are discharged from the city of Hanoi into urban rivers. Sediment samples from three sites in the To Lich River in Hanoi were assessed with respect to the concentrations and potential mobility of cadmium (Cd), nickel (Ni) and lead (Pb). Due to very high Cd concentrations up to 700 mg kg^?1 at one site, the sediment was considered highly unsuitable for any types of land use if dredged and disposed of on land. Chemical sequential extractions of wet and anoxic sediment samples showed that Cd and Pb were largely associated with the redox-sensitive fractions and could thus be mobilised following measures such as resuspension or dredging. To assess the potential mobilisation of heavy metals from the anoxic sediment due to oxidation, the samples were exposed to different oxidants (i.e. atmospheric air and hydrogen peroxide) and afterwards submitted to a leaching test. These experiments showed that although oxidation may increase the equilibrium pore water concentrations of heavy metals in the sediments, other sediment mineral fractions seem to effectively immobilise heavy metals potentially released from the oxidisable fraction.     

Study of leachability and fractional alteration of arsenic and co-existing elements in stabilized contaminated sludge using a flow-through extraction system

This study investigates the stabilization of As in the contaminated sludge after treatment with MnO(2) or Ca(OH)(2), and the influence of the stabilizing materials on the leachability of the co-existing elements Pb and Zn. By exploiting a continuous-flow assembly facilitating a modified Wenzel's sequential extraction scheme (designed for the fractionation of arsenic), it is possible to ascertain the leachability, mobility and fractional alteration of these elements under stimulated natural (flow-through) leaching conditions. The fractionation data show that more than 80% of As, Pb and Zn in the untreated sludge are bound in the amorphous Fe oxides fraction and residual fraction. The addition of MnO(2) has only an insignificant effect on As fractional transformation, while Ca(OH)(2) caused an increase in As mobility. For Pb, the decrease in leachability was clearly visible. The extractable Pb was reduced by 18% and 40% in stabilized MnO(2) and Ca(OH)(2) sludge samples, respectively. Unlike that of Pb, the mobility of Zn was not affected by the additives used. Their fractional distribution patterns before and after the stabilization process remained the same. The ability to produce detailed leaching profiles for As and other elements (Pb, Zn, Ca, Mn and Fe) meant that elemental associations in individual fractions could be examined. From the MnO(2)-treated sludge, the coincidence of the As, Pb, Zn, Fe, and Mn peaks seems to indicate a close association of these elements in the Fe-oxides-bound fraction. Furthermore, the leaching profiles may be used as evidence of a strong affinity between these elements and added MnO(2).     

Partitioning of mercury onto suspended sediments in estuaries

Radiochemical partitioning experiments using 203Hg have been undertaken with mixtures of river, seawater and sediment samples taken from three geochemically contrasting UK estuaries: the Plym, Beaulieu and Mersey. Species of dissolved Hg were determined using reversed-phase C18 chelating columns and particulate species were determined by sequential leaching with 1 M NH4OAc and 1 M HCl. Mercury had a high particle reactivity with partition coefficients, KDs, ranging from 10(4) to 5 x 10(5) ml g(-1), depending on salinity, the chemical composition of the end-member waters, and on the physico-chemical characteristics of the sediment. Dissolved organic matter present in the waters (humic substances and/or anthropogenic compounds) was found to be the main factor governing the forms of dissolved Hg and their reactivity. From the spiked 203Hg, up to 95% of the dissolved metal was retained on the C18 columns for the Mersey waters, whereas this fraction was < 60% in the Plym and Beaulieu waters. Quasi-irreversible adsorption of Hg onto particles from each estuary was observed over a time-scale of a few hours and < 20% of total particulate Hg was released by the sequential leach. In this paper, physico-chemical processes are proposed to explain the estuarine behaviour of Hg and the results are discussed in terms of Hg availability in estuarine systems.     

Mercury fractionation in contaminated soils from the Idrija mercury mine region

Mercury (Hg) fractionation was investigated in contaminated soil in the Idrija Hg-mine region, Slovenia. The main aim of this study was to test and apply sequential extraction and quantification of different Hg phases in order to estimate the mobility and potential bioavailability of Hg in contaminated soils. Separation of Hg phases was performed by means of a selective sequential extraction procedure complemented by volatilization of elemental mercury (Hg0). The influence of temperature, moisture and storage on Hg0 volatilization was also investigated. The total Hg concentrations varied between 8.4 and 415 mg kg(-1) and were up to 40-fold higher than the maximum permissible set by Slovenian legislation. Fractionation measurements indicated cinnabar as the predominant Hg fraction, followed by Hg0. Accumulation of cinnabar predominantly occurred in coarse grained flood plain sediments, where on average it constituted more than 80% of total Hg. In contrast non-cinnabar fractions were found to be enriched in areas where fine grained material was deposited, reaching up to 60% of total Hg. The strong positive correlation (R2 = 0.71-0.99) among non-cinnabar fractions suggested that these fractions predominantly control the mobility and potential bioavailability of Hg. Sample pretreatment before fractionation influenced the partition of Hg between different fractions, and therefore fractionation in fresh, nontreated samples is suggested. In addition, the specificity of the extraction steps needs further attention, as it was shown that some extraction steps, such as the organo-chelating Hg fraction, do not provide meaningful results. This further suggests that protocols for mercury fractionation need further harmonization in order to improve the comparability of the results and their use in risk assessment. Volatile mercury fluxes averaged between 0.04 and 6.5 ng g(-1) h(-1). Good agreement (R2 = 0.81-0.95) was found between the non-cinnabar fractions and evaporation of Hg0. Both the temperature and sample moisture had significant effects on mercury volatilization. The results in this study were obtained at 70 degrees C, which may be somewhat high, in particular for bacterial activity which may also play an important role in Hg volatilization. Therefore it is strongly suggested that further optimisation of the protocol to assess Hg volatilization from soil is required.     

Speciation of heavy metals in biosolids of wastewater treatment plants at Mysore,Karnataka, India

Urban wastewater treatment leads to the generation of large quantities of biosolids. Accumulation of biosolids is a problem of environmental relevance due to the existence of heavy metals in the biosolids. Determination of total metal in biosolid provides information relating pollution levels. Determination of their mobilization capacity and behaviour in the environment is an important task. An experimental approach commonly used for studying the mobility, transport and bioavailability of metal in biosolids is the use of selective sequential extraction procedure. In the present study an attempt has been made to study the heavy metal properties in biosolid samples collected from urban wastewater treatment plants located at Mysore, Karnataka. Few heavy metals selected for the present study are cadmium, chromium, copper, iron, nickel and zinc. The concentration of these metals in biosolids and their partition in different fractions are studied. The speciation of metals based on the sequential extraction scheme was carried out. The concentration of heavy metals is lower than that established by European legislation. The residual fraction has the maximum percentage of heavy metals whereas, only a small fraction of heavy metals (Fe, Zn and Cd) are extracted in the most soluble fractions, exchangeable and carbonate fractions.