Heavy Metals In Sewage Sludge Research Articles

Removal of copper from acid wastewater of bioleaching by adsorption onto ramie residue and uptake by Trichoderma viride

A continuous batch bioleaching was built to realize the bioleaching of sewage sludge in large scale. In the treatment, heavy metal in acid wastewater of bioleaching was removed by adsorption onto ramie residue. Then, acid wastewater was reused in next bioleaching batch. In this way, most time and water of bioleaching was saved and leaching efficiency of copper, lead and chromium kept at a high level in continuous batch bioleaching. It was found that residual heavy metal in sewage sludge is highly related to that in acid wastewater after bioleaching. To get a high leaching efficiency, concentration of heavy metal in acid wastewater should be low. Adsorption of copper from acid wastewater onto ramie residue can be described by pseudo first-order kinetics equation and Freundlich isotherm model. Trichoderma viride has the potential to be used for the concentration and recovery of heavy metal adsorbed onto ramie residue.

Vermiremoval of heavy metal in sewage sludge by utilising Lumbricus rubellus

Experiments were conducted to remove heavy metals (Cr, Cd, Pb, Cu and Zn) from urban sewage sludge (SS) amended with spent mushroom compost (SMC) using worms, Lumbricus rubellus, for 105 days, after 21 days of pre-composting. Five combinations of SS/SMC treatments were prepared in triplicate along with a control for each treatment in microcosms. Analysis of the earthworms' multiplication and growth and laboratory analysis were conducted during the tenth and fifteenth week of vermicomposting. Our result showed that the final biomass of earthworms (mg) and final number of earthworms showed significant differences between treatments i.e. F=554.70, P=0.00 and F=729.10, P=0.00 respectively. The heavy metals Cr, Cd and Pb contained in vermicompost were lower than initial concentrations, with 90–98.7percent removal on week ten. However, concentrations of Cu and Zn, that are considered as micronutrients, were higher than initial concentrations, but they were 10–200-fold lower than the EU and USA biosolid compost limits and Malaysian Recommended Site Screening Levels for Contaminated Land (SSLs). An increment of heavy metals were recorded in vermicompost for all treatments on week fifteen compared to week ten, while concentration of heavy metals in earthworms' tissue were lower compared to vermicompost. Hence, it is suggested that earthworms begin to discharge heavy metals into their surroundings and it was evident that the earthworms' heavy metals excretion period was within the interval of ten to fifteen weeks.

Use of Ornamental in Phytoremediation of Heavy Metals in Sewage Sludge

Goosegrass Herb ( Eleusine indica ) and Canna (Canna indica L.) were used to remove the heavy metals of Cu, Zn, Pb, Cd, Cr and Ni in the sewage sludge by potted planting. Taking the soil mixed by sludge and crimson soil according to sludge percent 25% to cultivate Goosegrass Herb and increasing the harvesting times could enhanced the removal efficiency of heavy metals significantly. Goosegrass Herb could be considered as the remediation plant for Cu, Zn, Cd and Ni. By Canna planting, final Zn, Ni and Cd contents in soil mixture could be reduced significantly, Canna could be used to reduce the Cd ,Ni and Zn concentration in sludge amended soil.

Fractionation of heavy metals in sewage sludge and their removal using low-molecular-weight organic acids

AbstractThe total concentration and the concentrations of individual chemical species of selected heavy metals were estimated in primary and anaerobically digested sewage sludge. The concentration of Zn (1503 mg/kg) was highest and was followed by Cu (201 mg/kg), Cr (196 mg/kg), Pb (56 mg/kg), Ni (44 mg/kg) and Cd (3.6 mg/kg). The metal was divided into 5 fractions (exchangeable (F1), adsorbed (F2), organically bound (F3), bound to carbonates (F4), and residual (F5)) via sequential extraction. The sludge treatment procedure had no significant effect on the fractionation results. In both the primary and anaerobically digested sewage sludge, the heavy metals were ranked according to their mobilities (fractions F1 and F2) in the following order: Ni > Zn > Cu > Cd > Pb > >Cr. Metal stability in the environment was evaluated by the sulphide and residual fraction F5, and the following ranking order was identified: Cr > >Pb≈Ni > Cd > Zn≈Cu. A leaching experiment with low-molecular-weight organic acids (oxalic, a...

Change of PCBs and forms of heavy metals in sewage sludge during thermophilic anaerobic digestion

Determination of seven congeners of PCBs was carried out for sewage sludge before, during and after thermophilic digestion. The overall content of heavy metals (Zn, Cu, Ni, Cd, Pb, Cr) in sludge before and after digestion was determined. Moreover the concentration of heavy metals in particular chemical fractions of the sludge was analyzed. After the thermophilic digestion total concentration of seven PCBs was reduced by 47%, which suggests that thermophilic digestion affects PCB reduction positively. On the 10th d of the process, concentration of lower chlorinated PCBs increased, whereas those of higher chlorinated PCBs decreased. The thermophilic digestion process showed no accumulation of the studied heavy metals in the mobile fractions (exchangeable and carbonate) of the stabilized sewage sludge, except for nickel. The highest increase in zinc, copper, cadmium, and chromium concentration was observed in the organic-sulfide fraction, whereas the highest increase in lead was found in the residual fraction of the sludge. In case of nickel both fractions of organic-sulfide and exchangeable–carbonate fractions were enriched.

Comparative Study on Physical and Chemical Characteristics of Sludge Vermicomposted by Eisenia Fetida

Abstract Prior to vermicompost application to the soils, there is a need to determine the heavy metal concentrations in the final vermicomposts. This study was designed to evaluate the effects of earthworm activity on heavy metals in sewage sludge. Com-pared with before vermicomposting by Eisenia fetida , the results are as follows: (1) water content, the pH value and organic matter content decreased, (2) total nitrogen content increased, total phosphorus content, total potassium content decreased, (3) available nitrogen concentration, available phosphorus content increased and, (4) the total content of five metals (Cu, Ni, Cd, Pb and Zn) decreased, and the bioaccumulation factor (BAF) shows that vermicomposting can efficiently remove heavy metals. Therefore, it can be concluded that the soil use of sludge of the Wastewater Treatment Plant in Huaibei is feasible.

Speciation of heavy metals in sewage sludge after mesophilic and thermophilic anaerobic digestion

AbstractTwo types of sewage sludge anaerobic digestion were carried out: mesophilic and thermophilic. Metal speciation analysis was performed revealing some changes in the chemical form of the metals during the stabilization process of sludge. After both methane fermentation processes, a comparable level of organic matter distribution was obtained (≈ 40 %). The amount of produced methane during thermophilic and mesophilic digestion was 560 mL of CH4 and 580 mL of CH4 from 1 g of removed organic matter, respectively. Low concentration of heavy metal ions in the liquid phase of sludge was observed. Metal ions precipitated and remained bound throughout the stabilization process. No accumulation of heavy metals in the mobile fractions of sludge (exchangeable and carbonate) was observed for either digestion process. The highest increase of zinc, copper, nickel, cadmium, and chromium concentration was observed in the organic-sulfide fraction, whereas the highest increase of lead was found in the residual fraction.

Immobilization of Cd, Zn and Pb in sewage sludge using red mud

Sewage sludge is an inevitable end by-product of sewage treatment. Land application provides a cost-effective alternative for sewage sludge disposal. However, sewage sludge contains heavy metals that may limit its application. In this work, red mud was employed for the immobilization of heavy metals in sewage sludge. The effect of red mud amendment on heavy metal immobilization was evaluated using Toxicity Characteristic Leaching Procedure (TCLP) method. The TCLP results showed that the immobilization efficiency of Cd, Zn and Pb was 100, 92, and 82%, respectively, when sewage sludge was mixed with 10% red mud. Tests carried out in leaching columns demonstrated that heavy metal concentrations in the leachate of 10% red mud amended sludge were lower than those of the unamended sludge. Moreover, red mud decreased plant available heavy metal (Cd, Zn and Pb) content from 18.1, 17.2 and 14.6% to 6.9, 11.4 and 7.6%, respectively. Sequential chemical extraction experiments showed that after sludge was amended with 10% red mud, exchangeable fraction was reduced and iron and manganese oxides fraction was increased. Red mud amendment can effectively immobilize Cd, Zn and Pb in sewage sludge before land application.

Influence and Mechanism of Different pH Values of Extractant on the Leachability of Heavy Metals in Industrial Sewage Sludge

The leaching tests of heavy metals in industrial sewage sludge were carried out under different pH of extractant by the solid waste extraction procedure for leaching toxicity (GB5086.2-1997) of China on the base of the contents and fractions of Zn, Cu, Pb, Cr, Mn and Ni elements. The results showed that the sludge was with higher levels of Mn and Zn, followed by Cu and Ni, while the higher toxicity of Pb and Cr was lower. The fractions of different elements in the sewage sludge had very different forms. The potential migration and biological toxicity were a concern for the active forms of Zn, Mn, Ni, Cr because their active proportions were more than 50%. The pH of extraction solutions had an important impact on the leaching of heavy metals in sewage sludge. The largest concentrations of Zn, Mn, Ni, Cu were appeared when the pH of extractant was about 7, but that of Fe had a greater fluctuation at the same pH. The concentrations of heavy metals had very different at different pH values, which may be related with the process of adsorption/desorption, complexation/dissociation, the dissolution/precipitation/co-precipitation and other chemical reactions in the extractant process.

Mechanisms and Effects of Extraction Time on the Leachability of Heavy Metals in Sewage Sludge from Guangzhou

The leaching tests of heavy metals in sewage sludge were carried out under different extraction time by the solid waste extraction procedure for leaching toxicity(GB5086.2-1997) of China on the base of the contents of Zn, Cu, Pb, Cr, Mn and Ni elements. The results showed that the sludge was with higher levels of Mn and Zn, followed by Cu and Ni, while the higher toxicity of Pb and Cr was lower, in which the order from the high to low was 1152mg/kg, 987mg/kg, 274mg/kg, 132mg/kg, 104 mg/kg and 87mg/kg, respectively. The extraction time had an important effects on the leaching of heavy metals in sewage sludge, in which the Zn, Ni, Cu leaching contents of the largest in range of 0-8h and Fe, Mn were increasing all through 0-24h. Different extraction time of the leaching amount of metals was very different, which may be related to the process of adsorption/desorption, complexation/dissociation, dissolution-precipitation/co-precipitation and other reactions.

Removal of heavy metals from sewage sludge with a combination of bioleaching and electrokinetic remediation technology

The combination of bioleaching and electrokinetic remediation has been proved to be an effective method to remove heavy metals from municipal sewage sludge. The results showed that using electrokinetic remediation for six days after bioleaching for four days, the contents of Cu and Zn in sewage sludge decreased from 296.4mgkg−1 and 3756.2mgkg−1 to 63.4mgkg−1 and 33.3mgkg−1, respectively, which could meet the Chinese standard for land application of the heavy metals in sewage sludge. During the bioleaching process, both the organic sulfide fraction of Cu and the carbonate-bound and organic sulfide fractions of Zn transformed to soluble and ionic fractions which could easily migrate to the electrode zone and then accumulate there, Finally, the soluble and ionic fractions of these heavy metals could be disposed of or recycled expediently at the end of electrokinetic remediation.

Distribution and mobility of heavy metals in sewage sludge

Distribution and mobility of heavy metals in sewage sludge

Total concentrations and chemical speciation of heavy metals in liquefaction residues of sewage sludge

The risk (including bioavailability and eco-toxicity) of heavy metals (Pb, Zn, Cu, Cd, Cr and Ni) in liquefaction residues (LR) of sewage sludge (SS) was estimated, according to both the speciation of heavy metals and the local environmental characteristics. The amount of organic matters in LR was lower than that in SS, resulting in a smaller calorific value, while the total content of heavy metals in LR nearly doubled. High residual rates of heavy metals (about 80%) indicated that the heavy metals in SS were concentrated into LR after liquefaction. The comparisons of sequential extraction results between SS and LR showed that after liquefaction, the mobile and easily available heavy metal fractions (acid soluble/exchangeable and reducible fractions) were mainly transformed into the relatively stable heavy metal fractions (oxidizable and residual fractions). The bioavailability and eco-toxicity of heavy metals in LR were relieved, though the total concentrations of heavy metals increased.

Bário, cádmio, cromo e chumbo em plantas de milho e em latossolo após onze aplicações anuais de lodo de esgoto

A presença de metais pesados no lodo de esgoto é uma das restrições quanto ao seu uso em áreas agrícolas. Este estudo teve por objetivo avaliar os efeitos da aplicação de doses de lodo de esgoto por 11 anos consecutivos em um Latossolo Vermelho distrófico sobre as concentrações de Ba, Cd, Cr e Pb em três profundidades no solo (0-10, 10-20 e 20-40 cm), bem como quantificar os mesmos metais na folha diagnose e nos grãos de milho. O experimento foi conduzido em condições de campo, utilizando-se o delineamento experimental em blocos casualizados com quatro tratamentos (0, 5, 10 e 20 t ha-1 de lodo de esgoto, base seca) e cinco repetições. As amostras de folha diagnose, solo, plantas inteiras e grãos foram obtidas, respectivamente, aos 60, 68, 80 e 123 dias após a emergência das plantas. A aplicação de doses de lodo de esgoto de 10 e 20 t ha-1 aumentou os teores de Ba, Cr e Pb na camada superficial do solo (0-10 cm), mas não alterou os de Cd. As doses do lodo de esgoto testadas não proporcionaram incrementos nas concentrações de Cd, Cr e Pb na folha diagnose e de Ba, Cd, Cr e Pb nas plantas de milho. A concentração de Ba na folha diagnose reduziu com a aplicação do resíduo. Os teores de Cd e Pb em grãos de milho permaneceram abaixo dos limites estabelecidos para o consumo humano, a concentração de Cr não pôde ser avaliada e nenhuma referência foi encontrada para comparar as concentrações de Ba.

Uptake of Heavy Metals by <i>Jatropha curcas</i> L. Planted in Soils Containing Sewage Sludge

Problem statement: The chemical pollution of soil has become a major source of concern and has posed serious health problems within the last few years in many developed nations. A variety of organic and inorganic pollutants, including heavy metals, are being mixed in with the cultivated soil and water. Sewage sludge was one of the major sources of enrichment of heavy metals. These pollutants are eventually transported to the natural vegetation and cultivated crops and concentrated in food chains, with possible detrimental effects on human health and wild-life. Thus, soil contaminants need to be cleaned up to improve environmental safety. Approach: Research was conducted to elucidate the potential of Jatropha curcas L. to clean toxic heavy metals derived from sewage sludge. J. curcas seedlings were planted on six different planting media T0 (100% soil-control), T1 (80% soil and 20% sewage sludge), T2 (60% soil and 40% sewage sludge), T3 (40% soil and 60% sewage sludge), T4 (20% soil and 80% sewage sludge) and T5 (100% sewage sludge) for a period of three months. The growth performance, including height and diameter, of J. curcas was measured using diameter tape, while the basal diameter was measured using a venier caliper every two weeks. Plant samples were collected after harvest and soil samples were collected before and after planting. The ICP-MS was used to determine the concentration of heavy metals in the planting medium and plant parts. Results: According to the growth parameters, the composition of 60% sewage sludge mixed with 40% soil was suitable for achieving optimum J. curcas growth. This plant was able to remove heavy metals (Zn, Pb, Cr, Cd and Cu) effectively from the medium containing 100% sewage sludge and after harvesting, the concentrations of Zn, Pb, Cr, Cd and Cu in T5(100% sewage sludge medium) were decreased by 67.7, 78.3, 77.2, 78.5 and 75.0%, respectively from the initial values. The highest levels of Zn (29.5 mg kg-1), Cu (0.44 mg kg-1) and Cd (8.35 mg kg-1) accumulation were found in the roots, whereas the highest Pb and Cr concentrations were observed in the leaves and stem, respectively. Conclusion/Recommendations: The roots of J. curcas were found to be suitable for the uptake of heavy metals in sewage sludge, especially Zn. Cr was also adsorbed effectively by the leaves. Thus, J. curcas was a suitable plant to use as a phytoremediator to clean heavy metals, in particular Zn, Cu and Cr. However, a study determining, the short term effects of the large scale use of sewage sludge on trees /-field crops/-leafy vegetables and environmental its impact needs to be carried out.

Sewage Sludge Carbonization for Terra Preta Applications

Sewage sludge is a renewable, negative-cost organic material that is well suited for the production of biocarbons. Due to increasing interest in the use of biocarbons for soil beneficiation and carbon sequestration (i.e., “terra preta” applications), the aim of this paper is an assessment of the production of sewage sludge charcoal for land application. By use of the flash carbonization process we measured sewage sludge charcoal yields near 30 wt % and fixed-carbon yields near 18 wt % from sludges with moisture contents near 7 wt %. Increasing the moisture content of the sludge reduced the charcoal and fixed-carbon yields; nevertheless, sewage sludge with 30 wt % moisture was successfully carbonized. The presence of heavy metals in sewage sludge is an important concern. We found that heavy metals with low boiling points (e.g., As, Cd, Hg, Se) were prone to elution from the carbonization reactor. Because the heavy metal content of the sludge used in this work was not high, the charcoal was found to be acce...

Test of the relationships between the content of heavy metals in sewage sludge and source of their pollution by chemometric methods

The content of various metals (Cd, Cr, Cu, Ni, Pb and Zn) in sewage sludge was analysed by ICP-OES technique. The study was performed on 14 samples from the Wielkopolska region and 4 from the neighbouring provinces. The results were used to perform chemometric analysis. Two chemometric methods were used to test the relationships between the content of heavy metals in sewage sludge and the sources of their pollution. The application of cluster analysis displayed important information about the identification of similar locations of sewage sludge sampling stations. This chemometric method showed that all the monitoring locations are grouped into three main clusters. Separated clusters present similarities between locations of the sewage treatment plants, which have the same kind of industrial plants in their catchment area. Principal component analysis enabled interpretation of the complex relationships between determined elements. Application of principal component analysis to the whole data set helped to distinguish only two sewage sludge stations (Ostrow Wlkp. and Poznan-Kozieglowy) that could be interpreted, each in different principal component thereby suggesting that element's concentration differ considerably. The interpretation of relationships between the rest of the stations was possible by performing PCA for the second time, but on the reduced data set (two above-mentioned stations were excluded). It distinguished two groups: (1) Gniezno, Srem, Kalisz, Inowrocław and Sroda Wlkp, and (2) Gostyn, Gniezno and Kalisz, which differ with regard to element's concentration.

Extraction of Cadmium from Sewage Sludge Using Polyepoxysuccinic Acid

Abstract Polyepoxysuccinic acid (PESA), as an environmental benign biodegradable chelant, was used to remove heavy metals from the sewage sludge of Shanghai Taopu Wastewater Treatment Plant. The extraction of cadmium (Cd) from sewage sludge using aqueous solution of PESA was studied. It was found that PESA was capable of extracting Cd from the sludge, and the extraction efficiency was dependent on both pH and the concentration of the chelating reagent. The extraction efficiency decreased gradually with increasing of pH, whereas the dependency on pH decreased as the concentration of PESA increased. In the case of the high PESA to total metal ratio, e.g., 10:1, the extraction efficiency reached above 70% within the pH range from 1 to 7. The highest extraction efficiency obtained in the experiment was 78%. By comparing the contents of the heavy metals in sewage sludge before and after the extraction, it was found that the extracted Cd came mainly from the four fractions: acid-soluble, reducible, oxidizable, and water-soluble fractions.

Chemical and Biological Leaching Methods to Remove Heavy Metals from Sewage Sludge: A Review

The removal of heavy metals (HMs) in sewage sludge (SS) is important since sludge is often disposed or applied on farmland to enhance soil fertility. The present study reviewed two conceptual approaches (chemical and biological leaching) of removing HMs present in SS. In the chemical leaching method, traditional acid treatment together with novel methods such as aeration, complexation and sequential extraction procedure have been reviewed extensively. Certain factors influence the removal of HMs in SS. These factors include; pH, leaching agent, redox potential, and contact time. Nitric acid (HNO3), hydrochloric acid (HCl), sulphuric acid (H2SO4), phosphoric acid (H3PO4), ethylenediamine tetraacetic acid (EDTA), as well as Thiobacillus thiooxidans and Thiobacillus ferrooxidans are the most widely studied leaching agents and substrates involved in the chemical and bioleaching processes. However, the bioleaching process has been proposed as a safe, efficient, economical, environmental friendly method to remove HMs in SS due to its simplicity, high yield of metal extraction, low acid consumption, and low sludge solids concentration. Nevertheless, the present review has noted that most researchers are of the opinion that more studies are needed in the bioleaching method in order to enhance its commercial attraction.

Study of heavy metal in sewage sludge and in Chinese cabbage grown in soil amended with sewage sludge

The study was performed to investigate the heavy metal content and availability for crops in sewage sludge and its accumulation in Chinese cabbage grown in sewage sludge amended soil. We determined the total and chemical fraction of As, Cr, Cd, Pb, Ni, Cu, Zn, Fe, Mg and Mn in sewage sludge and the total content of these metals in Chinese cabbage grown in soil amended with sewage sludge. Total content of all metals (except for As) was below the top limits for land application of sewage sludge in China. The majority of As, Cd, Pb, Zn and Fe was present in the residual fraction (70 – 95%) of the total concentration, and 21% of Cd, 59% of Cr and 56% of Cu were present in oxidizable fraction in sewage sludge. Most of the content of metals increased in Chinese cabbage with the increase in sludge amendments ratio, and the content of heavy metal As, Cd, Cr and Zn exceeded the top limits of metals content in China. Our results suggested that application of sewage sludge could enhance the output of vegetable while the risk of heavy metal should be of concern.