Metal Concentrations In Leachates Research Articles

Evaluating the leachable metals in Kaohsiung Harbor sediment using the toxicity characteristic leaching procedure (TCLP)

The toxicity characteristic leaching procedure (TCLP) method was used to analyze the contaminants in the sediment materials of Kaohsiung Harbor as to evaluate the pollution potential associated with the Kaohsiung Harbor. A total of 80 sediment samples were collected at 20 locations and characterized for water content, organic matter (OM), total nitrogen (TN), total phosphorus (TP), and total grease (TG) as well as the leachable and total metals. The results indicated that the leachable metal concentrations were below the low detectable levels for mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr), and silver (Ag), between 0.005 and 0.281 mg/L, 0.07 and 24.0 mg/L, and 0.013 and 0.221 mg/L for Cu, Zn, and Ni, respectively. The leachable metal concentration at the river mouth vicinity was higher than that at other locations indicating that upstream industrial and domestic wastewater discharges were the main pollutant sources. Results of correlation studies revealed that the OM concentration in the sediment was highly correlated with TN, TP, TG, and total metal as well as the leachable Cu, Zn, and Ni. The above observation indicates that the OM present in the sediment mainly comes from man-made pollutants. All leachable metals in the Kaohsiung Harbor sediment were blown by the US Environmental Protection Administration standard. Hence, the dredged sediment from Kaohsiung Harbor can be a useful sea-filling material for land reclamation; however, the continuing leaching of metals and its impact on the aquatic environment need to be studied further.

Impact of long-term organic residue recycling in agriculture on soil solution composition and trace metal leaching in soils

Recycling composted organic residues in agriculture can reduce the need of mineral fertilizers and improve the physicochemical and biological properties of cultivated soils. However, some trace elements may accumulate in soils following repeated applications and impact other compartments of the agrosystems. This study aims at evaluating the long-term impact of such practices on the composition of soil leaching water, especially on trace metal concentrations. The field experiment QualiAgro started in 1998 on typical loess Luvisol of the Paris Basin, with a maize–wheat crop succession and five modalities: spreading of three different urban waste composts, farmyard manure (FYM), and no organic amendment (CTR). Inputs of trace metals have been close to regulatory limits, but supplies of organic matter and nitrogen overpassed common practices. Soil solutions were collected from wick lysimeters at 45 and 100cm in one plot for each modality, during two drainage periods after the last spreading. Despite wide temporal variations, a significant effect of treatments on major solutes appears at 45cm: DOC, Ca, K, Mg, Na, nitrate, sulphate and chloride concentrations were higher in most amended plots compared to CTR. Cu concentrations were also significantly higher in leachates of amended plots compared to CTR, whereas no clear effect emerged for Zn. The influence of amendments on solute concentrations appeared weaker at 1m than at 45cm, but still significant and positive for major anions and DOC. Average concentrations of Cu and Zn at 1m depth lied in the ranges [2.5; 3.8] and [2.5; 10.5μg/L], respectively, with values slightly higher for plots amended with sewage sludge compost or FYM than for CTR. However, leaching of both metals was less than 1% of their respective inputs through organic amendments. For Cd, most values were <0.05μg/L. So, metals added through spreading of compost or manure during 14years may have increased metal concentrations in leachates of amended plots, in spite of increased soil organic matter, factor of metal retention. Indeed, DOC, also increased by amendments, favours the mobility of Cu; whereas pH variations, depending on treatments, influence negatively the solubility of Zn. Generic adsorption functions of these variables partly explain the variations of trace metal concentrations and helped to unravel the numerous processes induced by regular amendments with organic waste products.

Red cement-based decorative mortar prepared with dry electroplating sludge containing Pb as red pigment

Red cement-based decorative mortars were prepared with different content electroplating sludge containing Pb (EPSP), and their colors, water absorption, strengths, hydration characteristics and heavy metal leachabilities were investigated. The experimental results show that EPSP can adjust the mortar color well as the red pigments exclusively used in the decorative mortars. EPSP will result in the increase of water absorption, but the mortar produced with 5% EPSP still has the very satisfactory water absorption. The mortars with EPSP are provided with nearly the same compressive, flexural and tensile bond strengths as those of the control. EPSP has no notable influence on the paste hydration. But it can densify the mortar microstructures. It is also evident that heavy metal concentrations in leachates of the mortars with EPSP are far lower than the recommended in the GB5085.3-2007.

Assessment of Bioavailable Trace Metal Levels in Bed Sediment of River Water System

The study was carried out to assess contamination and seasonal variations in bioavailable forms of trace metal (Cd, Cr, Cu, Fe, Pb, Ni, Zn, Mn) concentrations in bed sediment. Sediment samples were collected from five sampling points during dry and rainy seasons along Mada River, Nasarawa state, Nigeria. The samples were extracted using HCl/HNO3 (3:1v/v) and Ethylenediaminetetraacetic acid (EDTA). Trace metal levels in the extracts were quantified using atomic absorption spectrometer (AAS). Enrichment factors (EF) and Geochemical index (IGeo) were also determined. Acid leachable metal concentrations in bed sediment were higher than the EDTA extractable trace metal levels during the rainy season. Sediments were enriched with Fe and Mn. Igeo index revealed class 0 – uncontaminated for the sediments during both seasons. Acid leachable Cu, Pb and Zn concentrations correlated positively and strongly for both periods of analysis; indicating same source and mechanism. Analysis of variance (ANOVA) indicated significant differences (P<.05) between acid leachable and EDTA trace metal concentrations. Metal concentrations, though higher during the rainy season, were below the Consensus-Based Sediment Quality Guidelines (CBSQG), the threshold and probable effect concentrations. Original Research Article British Journal of Applied Science & Technology, 4(19): 2808-2820, 2014 2809 The moderately to strongly contaminated nature of surface sediment could be as a result of anthropogenic source of metals entering the coastal zone through river inputs. Further study on the impact of trace metal contents in bed sediment on the quality of the overlying water column of the river is recommended.

Application of dry composite electroplating sludge into preparation of cement-based decorative mortar as green pigment

Abstract The objectives of this study were to assess the feasibility of application of dry composite electroplating sludge (CEPS) into preparation of cement-based decorative mortar as green pigment, and to find a new disposal and resource approach for it. Color, water absorption, strength, hydration and leachability of cement-based decorative mortar are investigated. The results show that CEPS can adjust the mortar color well. Although CEPS leads to the increase of mortar water absorption, the water absorption of mortar prepared with 5% CEPS still meets the requirement stated in the Chinese Building Material Industry Standard JC/T 1024-2007. The mortars with CEPS are provided with nearly same compressive, flexural and tensile bond strengths as these of the control. Cement hydration products such as C–S–H gel, Ca(OH) 2 and the entringite all can be observed in different specimens. The denser microstructures than that of the control are formed in the mortars with CEPS. It is found from almost similar intensity in Ca(OH) 2 peak at 18.007° that CEPS has not notably influence on the cement hydration. It is also evident that heavy metal concentrations in leachates of the mortars with CEPS are far lower than recommended in the Chinese National Standard GB5085.3-2007. It is safe to people's health and environment that CEPS is recycled as green pigment to produce cement-based decorative mortar.

Stabilization treatment of the heavy metals in fly ash from municipal solid waste incineration using diisopropyl dithiophosphate potassium

A stabilization treatment was developed for heavy metals in fly ash from municipal solid waste incineration using the heavy metal chelator diisopropyl dithiophosphate potassium (DDP). The mechanism and effect of the DDP chelator treatment on heavy metals in the fly ash was also studied, along with the form transformation rules of the heavy metals after DDP chelator treatment. The results show that 1% DDP achieves a stabilization rate of over 95% for Pb, Zn, and Cd. The effect of DDP was better than that of inorganic stabilizers such as sodium sulphide and lime. The heavy metal concentrations in the leachate after the treatment were lower than those required by the Pollution Control Standards for Hazardous Waste Landfill (GB18598-2001). At pH 1–13, the heavy metal concentrations in the fly ash leachate were far lower than those using the inorganic stabilizers sodium sulphide and lime. DDP retains its stabilizing effect under a broader pH range. After stabilization treatment, the heavy metals in the exchangeable fraction and those bound to carbonates were mainly transformed into those bound to organic matter. This process decreases the unstable content and reduces the risk of secondary pollution of the stabilized products in the environment.

Immobilization of heavy metals in sewage sludge by using subcritical water technology

Heavy metals (HMs) immobilization in sewage sludge was investigated by using subcritical water technology (SCWT) in this study. The characteristics of sludge and toxicity of HMs were analyzed after SCWT process. The results showed that besides large reduction in sludge volume, SCWT had some positive effect on HMs dissolution into liquid phase, while the majority of HMs was still accumulated in solid phase. The direct toxicity and bioavailability of HMs in sludge was greatly decreased with no toxicity fractions of HMs highly increased. Pb was always at low risk level and the risk of other HMs was greatly reduced from low risk to no risk after SCWT treatment. Moreover, the leaching toxicity of HMs declined after SCWT and the best result was obtained at 280°C with the metal concentrations in leachate decreased by 97.46%, 93.91%, 86.14%, 73.67%, 71.93% and 10.71% for Cu, Cd, Zn, Cr, Ni and Pb, respectively.

Trace metal concentrations in leachates from open dumpsites in Lokoja, Kogi state, Nigeria

Leachates from selected dumpsites and control site in Lokoja municipal were analyzed for trace metal concentrations. These parameters were compared with control samples and established international standards (FEPA) and (WHO). Dumpsite leachates contained very high concentrationsof iron (73.60±0.58)mg/L, manganese (16.53±0.309)mg/L, copper 1.00±0.02mg/L, zinc 2.41±0.042mg/L, and lead 1.55±0.097mg/L. All the parameters except nickel and cadmium were above the control and exceed FEPA and WHO guidelines. The study revealed that the dumpsite is amajor polluting source in the surrounding environment. This underlines the need for appropriate government agency of Kogi State, Nigeria to initiate active remediation process such as phytoremediation in combination with physiochemical methods to recover the dumpsite from contaminants and reduce the level of pollution in the surrounding environment.Keywords: Leachates, dumpsite, remediation, phyto remediation, trace metals.

Effect of Soil Washing and Liming on Bioavailability of Heavy Metals in Acid Contaminated Soil

Soil washing with acidic chelators followed by liming is under consideration for remediating multi-metal contaminated soils. This technique was tested by pot experiments with a mixture of chelators (MC) as a washing agent. After washing and liming treatments, corn (Zea mays L.) was planted to assess bioavailability of heavy metals. A phytoextraction with Sedum alfredii was additionally performed after corn harvest to further decrease heavy metals in the soil. The results showed that the concentrations of Cd, Pb, and Zn in the corn grain with the washing treatment were still higher than the food standard limits in China, and liming the washed soil did not effectively decrease Cd and Pb concentrations in the corn grain. Liming the washed soil significantly increased heavy metals concentrations in leachate. The concentrations of Cd, Pb, Zn, and Cu in S. alfredii after washing were increased by 42.8, 51.2, 7.3, and 25.8%, respectively, compared to nonwashed soils. Phytoextraction rates of Cd and Zn by one crop of S. alfredii after soil washing were 47.8 and 9.82%, respectively, of the soil total metal. The phytoextraction of soils with S. alfredii, and also the liming treatment alone without phytoextraction or washing, were able to reduce exchangeable heavy metal concentrations in soils. This study suggests that the bioavailability of heavy metals could still be high after washing, liming the washed soil may release the adsorbed metal-chelates, and the phytoextraction by S. alfredii after soil washing is an effective approach to deplete the mobile Cd activated by soil washing.

Batch and column studies of the stabilization of toxic heavy metals in dredged marine sediments by hematite after bioremediation

The management of dredged sediments is an important issue in coastal regions where the marine sediments are highly polluted by metals and organic pollutants. In this paper, mineral-based amendments (hematite, zero-valent iron and zeolite) were used to stabilize metallic pollutants (As, Cd, Cu, Mo, Ni, Pb, and Zn) in a contaminated marine sediment sample. Mineral-based amendments were tested at three application rates (5 %, 10 %, and 15 %) in batch experiments in order to select the best amendment to perform column experiments. Batch tests have shown that hematite was the most efficient amendment to stabilize inorganic pollutants (As, Cd, Cu, Mo, Ni, Pb, and Zn) in the studied sediment. Based on batch tests, hematite was used at one application rate equal to 5 % to conduct column experiments. Column tests confirmed that hematite was able to decrease metal concentrations in leachates from stabilized sediment. The stabilization rates were particularly high for Cd (67 %), Mo (80 %), and Pb (90 %). The Microtox solid phase test showed that hematite could decrease significantly the toxicity of stabilized sediment. Based on batch and column experiments, it emerged that hematite could be a suitable adsorbent to stabilize metals in dredged marine sediment.

Micro-structural and metal leachate analysis of concrete made with fungal treated waste foundry sand

Waste foundry sand (WFS) is a byproduct of metal casting industry which results from the mold and core making processes. Land filling is not considered to be a good option because it leads to the risks associated with the environment as it generates leachate which may contain heavy metals and organic contaminants. Its beneficial use in construction materials results in reducing the cost of construction materials’ ingredients and also helps in reducing disposal problem. Leaching characteristics are essential in understanding the environmental impact or toxicity, disposal and potential development of beneficial applications of WFS. This study aimed to presents micro-structural and metal analysis of fungal treated leachate obtained from concrete made with various percentages of WFS (0%, 10%, 15% and 20%).Metal concentrations of untreated and fungal treated leachate obtained from concrete made with WFS were analyzed for 15 metals including (Ba, Be, Cd, Cr, Co, Cu, Fe, Hg, Li, Mo, Mg, Mn, Ni and Zn) by using ICP-MS and compared with world Health organization (WHO) standard limits and ground water quality standards (GWQSs). Metal analysis indicates that WFS contribute to the concentration of leachable metals in concrete containing WFS. Results show the reduction in the metal concentration in leachate obtained from fungal treated concrete. In fungus (Aspergillus niger) treated WFS (10%) containing concrete, the metal concentration in Cd, Cr, Fe, Mo, Mn, Ni and Pb were reduced to significant levels. Micro-structural analysis confirms the improvement of concrete by inclusion of fungal treated WFS in concrete due to the formation of calcium rich biomineral in the pores of concrete.

Utilization of municipal solid waste incineration bottom ash in blended cement

The objective of this study was to assess the feasibility of application of municipal solid waste incineration (MSWI) bottom ash as a supplementary cementitious material for the preparation of blended cement. The water demand for normal consistency, setting time, strength and hydration characteristics of MSWI bottom ash–cement compound matrices were investigated. The results show that the MSWI bottom ash has some cementitious activity, but the reactivity is relatively lower than Portland cement and its addition to cement may lead to retardation of cement hydration. The incorporation content of MSWI bottom ash in blended cements was controlled below 30%, which resulted in blended cement of strength class 32.5 according to GB 175-2007 (Chinese National Standard). It is also evident that heavy metal concentrations in leachates of the blended cements with MSWI bottom ash are far lower than recommended in the GB5085.3-2007.

Characteristics of a Coal Fly Ash Subjected to Additional Processing

Abstract This paper presents the results of a study of the physical and environmental properties of pre- and post-processed fly ashes (termed Raw and Processed fly ashes, respectively). The ashes were collected from a coal-fired power plant in the northeastern U.S. which utilizes a carbon burn-out unit (CBO) to prepare the fly ash for concrete and other construction applications. Measured physical properties included carbon contents via loss-on-ignition (LOI), specific gravities, gradation analyses, and scanning electron microscopy (SEM). In addition, total and leachable concentrations of lead, selenium, and arsenic were determined. Leachable concentrations were determined for leaching solution pHs varying between 1.5 and 11.5. When compared to Processed fly ash, Raw fly ashes had an expectedly higher LOI (approximately 2% versus 6% carbon content, respectively) and lower specific gravity (2.37 versus 2.18, respectively). Although the total metal content of the fly ashes was similar, leachable metal concentrations were notably higher for the Processed fly ash over the full range of leaching solution pHs evaluated. The test results indicate that the CBO process, at times necessary to create usable fly ash, can result in fly ashes with notably altered physiochemical properties that lead to higher leachable contaminant concentrations.

Characterization and treatment of Denizli landfill leachate using anaerobic hybrid/aerobic CSTR systems

Leachate generated in municipal solid waste landfill contains large amounts of organic and inorganic contaminants. In the scope of the study, characterization and anaerobic/aerobic treatability of leachate from Denizli (Turkey) Sanitary Landfill were investigated. Time‐based fluctuations in characteristics of leachate were monitored during a one‐year period. In characterization study; chemical oxygen demand (COD), biochemical oxygen demand (BOD) dissolved oxygen, temperature, pH, alkalinity, volatile fatty acids, total nitrogen, NH4‐N, BOD5/COD ratio, suspended solid, inert COD, anaerobic toxicity assay and heavy metals concentrations in leachate were monitored. Average COD, BOD and NH4‐N concentration in leachate were measured as 18034 mg/l, 11504 mg/l and 454 mg/l, respectively. Generally, pollution parameters in leachate were higher in summer and relatively lower in winter due to dilution by precipitation. For treatment of leachate, two different reactors, namely anaerobic hybrid and aerobic completely stirred tank reactor (CSTR) having effective volumes of 17.7 and 10.5 litres, respectively, were used. After 41 days of start‐up period, leachate was loaded to hybrid reactor at 10 different organic loading rates (OLRs). OLR was increased by increasing COD concentrations. COD removal efficiency of hybrid reactor was carried out at a maximum of 91%. A percentage of 96% of residual COD was removed in the aerobic reactor. NH4‐N removal rate in CSTR was quite high. In addition, high methane content was obtained as 64% in the hybrid reactor. At the end of the study, after 170 operation days, it can be said that the hybrid reactor and CSTR were very effective for leachate treatment.

Exposure of an anoxic and contaminated canal sediment: Mobility of metal(loid)s

A derelict canal contains an estimated 9800 tonnes of anoxic sediment with highly elevated concentrations of trace elements. Lack of maintenance, reduced water levels and vegetation colonization threaten the stability of pollutants by removing existing waterlogged reduced conditions. A column leaching study of the sediment under increasingly oxidized conditions showed reductions in As mobility but increased heavy metal concentrations. In a reduced state, As mobility was higher (as a consequence of enhanced Fe and organic carbon solubility) whilst heavy metal concentrations in leachates were lower (due to markedly higher pH). Over 10 contiguous wetting and drying cycles, the consequences were profound; all trace elements were continuously leached with enhanced flushing of Fe, As, Zn and Cu. This raises concern over possible mobilization of pollutants to the wider environment, including groundwater. Options for management to stabilize contaminants are discussed that point to the importance of limiting water flow through the sediment.

Chemical Characterization of Metal-Contaminated Soil in Two Study Areas in Finland

The chemical characterization of contaminated soil was assessed in two study areas in Finland contaminated with metals. The aqua regia extractable and/or concentrated nitric acid leachable median concentrations of selected elements within the study areas were first compared to those from various geochemical baseline studies. Based on this comparison, the studied elements were divided into two groups: elements displaying general enrichment in the study areas and those with median concentrations within the range of baseline levels. In addition to comparison with the baseline levels, the distribution of aqua regia extractable concentrations of selected elements was assessed in relation to the Finnish soil screening values. The potential leachability of the selected metallic elements in contaminated, mainly man-made soil was examined by determining the ratio between the median ammonium acetate and median aqua regia extractable concentrations in the two study areas. Aqua regia extractable concentrations are considered to represent the near-total fraction of the elements and ammonium acetate extractable concentrations the ‘bioavailable’ fraction. These ratios were compared with those from non-polluted sites representing geochemical baselines. In addition, water soluble element concentrations were available from the two study areas and the ratio between synthetic rainwater or distilled, de-ionised water extractable and aqua regia extractable concentrations was calculated. The ratio between ammonium acetate extraction and aqua regia extraction indicated that of the studied elements, Cu, Ni, Pb, Zn and V exist in a more leachable form in contaminated soil than in the natural environment. It can be assumed that these elements are also more ‘bioavailable’ in contaminated land and could therefore pose a risk to the environment. The water soluble fraction of the potential harmful elements was generally low in both study areas, but single samples had easily leachable metal concentrations. High concentrations of trace elements were found in the groundwater on the down stream side of the potential pollution source. The chemical characteristics of the soil material in both study areas were defined with hierarchical cluster analysis, with the results presented as dendrograms produced using Ward’s method. Although some clusters were identified from the dendrograms, no special characterization of the fill material was possible. However, suggestive grouping of certain element groups was observed. Similar grouping of elements was found in factor analysis. Cluster analysis as well as factor analysis was found to be feasible for the chemical characterization of soil provided that a sufficient number of samples with appropriate analysis are available.

Monitoring heavy metal concentrations in leachates from a forest soil subjected to repeated applications of sewage sludge

The aim of the study was to establish whether the repeated application of sewage sludge to an acid forest soil (Dystric Cambisol) would lead to short-term groundwater contamination. Sludge was applied at four loading rates (0, 2.4, 17 and 60 Mg ha(-1)) in two consecutive years and leachates were analysed. Heavy metal inputs to soils at the lowest dose were below EC regulations but, at higher doses, limits for Zn, Cd, Cr and Ni were exceeded. Repeated application of sludge at 60 Mg ha(-1) resulted in significantly (P<0.05) higher concentrations of Zn, Cd, Cr and Ni in the leachates than with other treatments. The drinking water standards for Cd and Ni were surpassed in all treatments. Control plots were contaminated by groundwater flow despite the existence of buffer zones between plots. This complicated interpretation of the results, highlighting the importance of careful design of this type of experiment.

Modeling of Heavy Metals Removal from Municipal Landfill Leachate Using Living Biomass of Water Hyacinth

Water Hyacinth, Eichhornia crassipes, a fast-growing floating aquatic macrophyte; was used for the removal of heavy metals from a municipal landfill leachate. The leachate was spiked with different mixtures of five heavy metals (Cd, Cr, Cu, Pb and Ni), at a range of concentrations to cover the ranges reported in literature. The initial concentrations of the total heavy metals in leachate ranged from 0.06 to 5.5 mequiv L−1. All experiments were carried out in batch reactors in a greenhouse environment. The water hyacinth plants showed a very promising ability to remove and accumulate these metals from the leachate (24% to 80% removal of total heavy metals). Generally, the reduction in concentration of total heavy metals followed two distinct patterns, a rapid initial decrease followed by a slower decrease. An exponential mathematical model was established to estimate the remaining concentration of total heavy metals in the leachate over time for the rapid initial decrease. Also, a linear relationship was established to estimate the concentration of total heavy metals over time for the slower decrease. In addition, Langmuir and Freundlich isotherms were applied to the observed data and the constants of each isotherm were obtained.

Effect of Microwave Radiation on Immobilization of Heavy Metals in Sediment Sludge

In order to evaluate the effect of microwave radiation on immobilization of heavy metals (Cu 2 + , Cr 6 + , Zn 2 + and Pb 2 + ) in sediment sludge, leaching tests were run under different test conditions to compare microwave radiation with conventional blast heating and drying process for their effectiveness in immobilizing heavy metals within sediment sludge. Experimental results indicate that microwave radiation can decrease the concentration of heavy metals in leachate by 63% ∼ 70% more than conventional blast heating and drying process in an aclinic shake leaching test. Under the same simulated natural water conditions, the concentration of heavy metals in the leachate using microwave radiation is well below the concentration of heavy metals in leachate using conventional blast heating and drying process. It is therefore concluded that microwave radiation is much more effective than conventional blast heating and drying process in immobilizing heavy metals in sediment sludge.

Performance results from the Tucumán solid waste bioreactor

Performance results obtained from a 6200 ton demonstration-scale anaerobic bioreactor, constructed on the Pacara Pintada Landfill in Tucumán, Argentina, are described. The operational aspects over a 30-month period for the Tucumán bioreactor demonstrate the ability to maintain the bioreactor in the mesophilic range, with the result that the generation and collection of the biogas has been maintained at accelerated rates with a rate constant of approximately 0.5 year −1. Field measurements of metal concentrations in leachate indicated significant attenuation over time. Refuse subsidence, measured over a 28-month period, ranged from 4% to 19%, with an average of 11% subsidence across the Tucumán cell.