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PubMed2001

Evaluation of groundwater and soil pollution in a landfill area using electrical resistivity imaging survey.

Landfills are sources of groundwater and soil pollution due to the production of leachate and its migration through refuse. This study was conducted in order to determine the extent of groundwater and soil pollution within and around the landfill of Seri Petaling located in the State of Selangor, Malaysia. The condition of nearby surface water was also determined. An electrical resistivity imaging survey was used to investigate the leachate production within the landfill. Groundwater geochemistry was carried out and chemical analysis of water samples was conducted upstream and downstream of the landfill. Surface water was also analyzed in order to determine its quality. Soil chemical analysis was performed on soil samples taken from different locations within and around the landfill in the vadose zone (unsaturated zone) and below the water table (in the soil saturated zone). The resistivity image along line L-L1 indicated the presence of large zones of decomposed waste bodies saturated with highly conducting leachate. Analysis of trace elements indicated their presence in very low concentrations and did not reflect any sign of heavy metal pollution of ground and surface water or of soil. Major ions represented by Na, K, and Cl were found in anomalous concentrations in the groundwater of the downstream bore hole, where they are 99.1%, 99.2%, and 99.4%, respectively, higher compared to the upstream bore hole. Electrical conductivity (EC) was also found in anomalous concentration downstream. Ca and Mg ions represent the water hardness (which is comparatively high downstream). There is a general trend of pollution towards the downstream area. Sulfates (SO4) and nitrates (NO3) are found in the area in low concentrations, even below the WHO standards for drinking water, but are significantly higher in the surface water compared to the groundwater. Phosphate (PO4) and nitrite (NO2), although present in low levels, are significantly higher at the downstream. There is no significant difference in the amount of fluoride (F) in the different locations. In the soil vadose zone, heavy metals were found to be in their typical normal ranges and within the background concentrations. Soil exchangeable bases were significantly higher in the soil saturated zone compared to the vadose zone, and no significant difference was obtained in the levels of inorganic pollutants. With the exception of Cd, the concentration ranges of all trace elements (Cu, Zn, Cr, Pb, and Ni) of Seri Petaling landfill soils were below the upper limits of baseline concentrations published from different sources.

Aluminum Silicates↗
PubMed1996

Effect of microwave heating on leaching of lead from old ceramic dinnerware.

When samples of pre-1950s U.S.-made ceramic dinnerware, purchased in antique shops and flea markets, were filled with 4% acetic acid or 0.5% citric acid and heated in a microwave oven for 2-5 min, lead was leached in amounts of up to 5 mg per dish. Concentrations of lead in the leachates were not significantly correlated with, and could not be predicted from, concentrations in leachates measured during 24-h room temperature acid leaching tests. Unsafe lead concentrations (>3 microg/ ml) were found in microwave leachates of dishes with uranium-containing glazes, with copper-containing glazes, and with floral over-the-glaze decals. This evidence suggests that use of such dishes to microwave common foods could result in the ingestion of dangerously large amounts of lead.

Acetic Acid↗
PubMed1986

The effects of Love Canal soil extracts on maternal health and fetal development in rats.

The effects of a solvent extract of the surface soil of the Love Canal chemical dump site, Niagara Falls, New York, and of a natural extract, or leachate, which is drained from the canal for treatment, on the maternal health and fetal development were determined in rats. The solvent extract, which was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (2, 3,7,8-TCDD) at 170 ppb and numerous other chlorinated organic compounds with the primary identified components being the isomers of benzenehexachloride (BHC), was dissolved in corn oil and administered by gavage to pregnant rats at 0,25,75, or 150 mg crude extract/kg/day on Days 6-15 of gestation. A 67% mortality was observed at the highest dose. The rats were sacrificed on Day 20. Dose-related increases in relative liver weight accompanied by hepatocyte hypertrophy were observed at all dose levels. Fetal birthweight was decreased at 75 and 150 mg extract/kg/day. No major treatment-related soft tissue or skeletal malformations, except for delayed ossification, were observed. Based on literature values for BHC, all of the observed toxicity could be accounted for by the BHC contaminants of the extract. The crude organic phase of the leachate was administered to pregnant rats at 0,10,100, or 250 mg/kg/day as described above. Maternal weight gain decreased at 100 and 250 mg/kg/day, accompanied by 5 and 14% maternal mortality, and 1 and 3 dead fetuses, respectively. Early resorptions and the percentage of dead implants increased whereas fetal birthweights were decreased at 250 mg/kg/day. No major treatment-related soft tissue or skeletal malformations, except for delayed ossification, were observed. The primary components of the complex leachate by mass were tetrachloroethanes; however, 2,3,7,8-TCDD, which was present at 3 ppm, probably accounted for all the observed toxicity.

Abnormalities, Drug-Induced↗
PubMed1996

Comparison of aerobically-treated and untreated crop residue as a source of recycled nutrients in a recirculating hydroponic system.

This study compared the growth of potato plants on nutrients recycled from inedible potato biomass. Plants were grown for 105 days in recirculating, thin-film hydroponic systems containing four separate nutrient solution treatments: (1) modified half-strength Hoagland's (control), 2) liquid effluent from a bioreactor containing inedible potato biomass, 3) filtered (0.2 micrometer) effluent, and 4) the water soluble fraction of inedible potato biomass (leachate). Approximately 50% of the total nutrient requirement in treatments 2-4 were provided (recycled) from the potato biomass. Leachate had an inhibitory effect on leaf conductance, photosynthetic rate, and growth (50% reduction in plant height and 60% reduction in tuber yield). Plants grown on bioreactor effluent (filtered or unfiltered) were similar to the control plants. These results indicated that rapidly degraded, water soluble organic material contained in the inedible biomass, i.e., material in leachate, brought about phytotoxicity in the hydroponic culture of potato. Recalcitrant, water soluble organic material accumulated in all nutrient recycling treatments (650% increase after 105 days), but no increase in rhizosphere microbial numbers was observed.

Aerobiosis↗
PubMed2005

Improving acidogenic performance in anaerobic degradation of solid organic waste using a rotational drum fermentation system.

The effects of leachate from a methanogenic process on acidogenic performance of a solid recycle (SR) process by a rotational drum fermentation (RDF) system were evaluated under mesophilic condition and a hydraulic retention time (HRT) of 20 days. Two SR process configurations, SR1 and SR2, were evaluated, using fresh soybean meal or Okara as substrates. An apparent first-order hydrolysis rate constant of 5.0 x 10(-3)/d for SR1 at pH values of 4.4 and 14.4 x 10(-3)/d for SR2 at pH of 5.0, were obtained. The apparent volatile solids (VS) degradation ratio ranged from 9.6% to 19.4% and total volatile acid (as acetic acid) from 10.8 to 14.9 g/L. Occupying ratios for ionized volatile acid (VA) increased from 30.6% to 63.4% after recycling the leachate to process. However, occupying ratios of acetic acid decreased from 93.3% to 42.0% whereas propionic acid and butyric acid ratios increased in SR2. Integrating the VA production with the hydrolysis rate constants, it is clear that the recirculation of leachate considerably enhanced acidogenic performance of solid recycle process.

Bacteria, Anaerobic↗
PubMed2006

Anaerobic digestion of municipal solid waste as a treatment prior to landfill.

Anaerobic digestion of organic fraction of municipal solid waste was conducted in pilot-scale reactor based on high-solid combined anaerobic digestion process. This study was performed in two runs. In Run 1 and Run 2, pre-stage flushing and micro-aeration were conducted to determine their effect in terms of enhancing hydrolysis and acidification in ambient condition. In Run 2, after pre-stage, the methane phase (methanogenesis) was started-up after pH adjustment and inoculum addition in mesophilic condition. Acidified leachate produced in pre-stage was used for percolation during active methane phase. At the end of methane phase, air flushing was conducted before unloading the digesters. Hydrolysis and acidification yield of 140 g C/kg TS and 180 g VFA/kg TS were achieved, respectively in pre-stage. Micro-aeration exhibited an equivocal result in terms of enhancing hydrolysis/acidification; however it showed a positive effect in methane phase performance and this needed further investigation. Leachate percolation during methane phase showed an enhanced methanization when compared to the reactors without leachate percolation. After 60 days, 260 l CH(4)/kg VS was obtained. Based on the waste methane potential, 75% biogas conversion and 61% VS degradation were achieved.

Anaerobiosis↗
PubMed2004

Ion mobility based on column leaching of South African gold tailings dam with chemometric evaluation.

New column leaching experiments were designed and used as an alternative rapid screening approach to element mobility assessment. In these experiments, field-moist material was treated with an extracting solution to assess the effects of acidification on element mobility in mine tailings. The main advantage of this version of column leaching experiments with partitioned segments is that they give quick information on current element mobility in conditions closely simulating field conditions to compare with common unrepresentative air-dried, sieved samples used for column leaching experiments. Layers from the tailings dump material were sampled and packed into columns. The design of columns allows extracting leachates from each layer. The extracting solutions used were natural (pH 6.8) and acidified (pH 4.2) rainwater. Metals and anions were determined in the leachates. The concentrations of metals (Ca, Mg, Fe, Mn, Al, Cr, Ni, Co, Zn, and Cu) in sample leachates were determined using ICP OES. The most important anions (NO3-, Cl-, and SO4(2)-) were determined using the closed system izotacophoresis ITP analyser. The chemical analytical data from tailings leaching and physico-chemical data from field measurements (including pH, conductivity, redox potential, temperature) were used for chemometric evaluation of element mobility. Principal factor analysis (PFA) was used to evaluate ions mobility from different layers of tailings dump arising from varied pH and redox conditions. It was found that the results from the partitioned column leaching illustrate much better complex processes of metals mobility from tailings dump than the total column. The chemometric data analysis (PFA) proofed the differences in the various layers leachability that are arising from physico-chemical processes due to chemical composition of tailings dump deposit.

Anions↗
PubMed2006

Leaching characteristics of polybrominated diphenyl ethers (PBDEs) from flame-retardant plastics.

To investigate the effect of leachant on the leachability of polybrominated diphenyl ethers (PBDEs), we determined the leaching concentrations of PBDEs from flame-retardant plastic samples (TV housings and raw materials before molding processing) that are regarded as a source of PBDEs in landfill sites. The leachants used were distilled water, 20% methanol solution, and dissolved humic solution (DHS) of 1000 mg/l based on organic carbon. The leaching test conditions were a liquid-to-solid ratio of 100:1, and a contact period of five days, with twice-daily agitation in a temperature-controlled room of 30 degrees C without pH or ionic strength control. The leaching concentrations of PBDEs increased with increased content, and were found to be remarkably enhanced when methanol and DHS were used instead of distilled water. The enhancement of leachability in the presence of the latter was attributed to the cosolvency effect, and complex formations between the PBDEs and dissolved humic matter (DHM). PBDE concentrations in the leachate obtained from the leaching test and an actual landfill site revealed a significant presence of congeners below heptabromodiphenyl ethers (H7BDEs), detected in the leachate of the actual landfill, while significant amounts of nonabromodiphenyl ethers (N9BDEs) and decabromodiphenyl ether (D10BDE) were detected in the leachate of the leaching test.

Flame Retardants↗
PubMed2006

Determination of polybrominated diphenyl ethers at trace levels in environmental waters using hollow-fiber microporous membrane liquid-liquid extraction and gas chromatography-mass spectrometry.

In this study, we present a simple and easy-to-use extraction method that is based on a hollow-fiber microporous membrane liquid-liquid extraction (HF-MMLLE), as an extraction technique, followed by gas chromatography-mass spectrometry (GC-MS) to determine a group of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs), at trace levels in aqueous samples. The hollow-fiber membrane (HF) filled with organic solvent was immersed into the aqueous sample, spiked with the analytes at ng l(-1) level, and stirred for 60 min. The proposed method could attain enrichment factors (E(e)) up to 5200 times, after optimising parameters, such as organic solvent, stirring speed and extraction time, that affect the extraction. The HF-MMLLE-GC-MS method was successfully applied to the extraction of PBDEs from tap, river and leachate water samples with spike recoveries ranging from 85% to 110%. The method validation with reagent and leachate water samples provided good linearity, detection limits of 1.1 ng l(-1) or lower, both in reagent and leachate water, as well as satisfactory precision in terms of repeatability and reproducibility with values of % relative standard deviation (%RSD) lower than 8.6 and 16.9, respectively.

Bromine↗
PubMed2006

Release and leaching of plant DNA in unsaturated soil column.

Little information is available on the process of DNA release from plants and neither is there much information to be found regarding DNA transport in the vadose zone. Unsaturated soil columns were used to examine the release and transport of DNA content in the leaf of tomato variety Palmiro, which was introduced into the soil columns after being dried at 35 degrees C for 3 days. Soil columns were leached with sterile water at a rate of 0.5mLh(-1) for 104 days. DNA from column leachate water was extracted and analysed. Both quantitative and qualitative measurements of extracted DNA were taken. Tomato gene sequences were detected using PCR amplification based on tomato specific 18S primers. The concentration of total DNA in soil column leachate water ranged from 6.7 to 50.4microgL(-1). Genomic analysis using agarose gel electrophoresis showed degradation of DNA after its passage through unsaturated soil columns. The presence of tomato genes in the leachate water of soil columns suggests a potential release of tomato DNA from leaves and potential transport of DNA over considerable distances in water-unsaturated soil. Consequently, transport of plant DNA in vadose zone is indicated, and there is a risk that the DNA may reach the groundwater.

DNA, Plant↗
PubMed2004

Arsenic and heavy metal mobility in iron oxide-amended contaminated soils as evaluated by short- and long-term leaching tests.

Several iron-bearing additives were evaluated for their effectiveness in the attenuation of arsenic (As) in various contaminated soils. These were selected for their known or potential ability to adsorb As anions, thus changing the speciation of As in a soil system. Three soils with different sources of As contamination were investigated (canal dredgings, coal fly ash deposits, and low-level alkali waste). The amendments used were goethite (alpha-FeOOH), iron grit, iron (II) and (III) sulphates (plus lime), and lime, applied to the soils at a rate of 1% w/w. A series of leachate extraction tests (UKEA, ASTM and modified Dutch column leaching test) were conducted on the equilibrated amended soils. These were used to firstly evaluate the potential of the amendments as immobilising agents, and secondly to compare the short- and long-term durability of their effects. Column tests demonstrated the efficiency of iron oxides over the longer time scale; these treatments significantly reduced concentrations of arsenic in leachates from all treated soils. Amended soils were also observed to contain higher levels of lead (Pb) and cadmium (Cd) in their leachates, signifying that certain Fe-oxides potentially increased heavy metal mobility in treated soils. The conclusions were that whilst Fe-oxides may be used as effective in situ amendments to attenuate As in soils, their effects on other trace elements, such as Pb and Cd, require careful consideration.

Adsorption↗
PubMed2005

Diuron mobility through vineyard soils contaminated with copper.

The herbicide diuron is frequently applied to vineyard soils in Burgundy, along with repeated treatments with Bordeaux mixture (a blend of copper sulfate and calcium hydroxide) that result in elevated copper concentrations. Cu could in principle affect the fate and transport of diuron or its metabolites in the soil either directly by complexation or indirectly by altering the populations or activity of microbes involved in their degradation. To assess the effect of high Cu concentrations on diuron transport, an experiment was designed with ten undisturbed columns of calcareous and acidic soils contaminated with 17--509 mg kg(-1) total Cu (field-applied). Grass was planted on three columns. Diuron was applied to the soils in early May and in-ground lysimeters were exposed to outdoor conditions until November. Less than 1.2% of the diuron applied was found in the leachates as diuron or its metabolites. Higher concentrations were found in the effluents from the grass-covered columns (0.1--0.45%) than from the bare-soil columns (0.02--0.14%), and they were correlated with increases in dissolved organic carbon. The highest amounts of herbicide were measured in acidic-soil column leachates (0.98--1.14%) due to the low clay and organic matter contents of these soils. Cu also leached more readily through the acidic soils (32.8--1042 microg) than in the calcareous soils (9.5--63.4 microg). Unlike in the leachates, the amount of diuron remaining in the soils at the end of the experiment was weakly related to the Cu concentrations in the soils.

Agriculture↗
PubMed2006

Leaching of metals from sewage sludge during one year and their relationship to particle size.

Leaching of metals from sewage sludge can lead to their accumulation in topsoil and can also contaminate groundwater. Our objectives were to document the metal leachates and the size distribution of leached particles from sewage sludge and to identify possible correlations with physical factors. Results from monthly lysimeter sampling showed an initial release followed by decline for most metals. Cadmium, Ca, Sr, Li, Mn, Ni and Zn showed a "cyclic" behaviour. Filtration revealed that this "cyclicity" had no correlation to the size of released particles, but Al, Cr, Fe, Cu, Ag and Pb were clearly related to release of coarser particles most of the year. Total metal amounts leached during one year, relative to original sludge content, had the order Na>Ca=Mg>Mn>Sr>Zn>K>Li=Ni>Cd>Co>Rb>Ag>Cr>Ba=Cu>Ga>Al=Pb=Fe. There were no simple correlations between monthly measured leachate concentrations and precipitation, temperature or pH of precipitation. Occasional leachate sampling might give misleading values for metals with "cyclic" behaviour.

Adsorption↗
PubMed2005

An in vivo model to assess factors that may stimulate the generation of an immune reaction to erythropoietin.

The incidence of pure red cell aplasia (PRCA) in patients with chronic kidney disease associated with the subcutaneous (s.c.) administration of epoetin alfa (EPREX) began to increase in 1998. As part of an intensive investigation into the reasons for this increase, in vivo models were developed to assess the ability of potential causative factors to stimulate an immune response to recombinant human erythropoietin (rHuEPO). It was difficult to generate anti-EPO antibodies in mice. In animals injected with rHuEPO alone, anti-EPO antibodies were either absent or present at very low levels. The addition of an adjuvant to the immunization protocol was able to increase both the frequency of occurrence and titer of the immune response and resulted in the generation of anti-EPO antibodies that, in most cases, recognized both human and mouse EPO. Some mice exhibited a reduction in hematocrit, suggesting neutralization of endogenous EPO by anti-EPO antibodies. To evaluate the primary lead identified in the technical investigation, leachates from the uncoated syringe stoppers of EPREX syringes, a surrogate antigen (chicken egg albumin, OVA) was used to avoid possible interferences that could arise from the use of an endogenous protein like EPO. These leachates yielded a positive, concentration-dependent antibody response in the OVA animal model, demonstrating their adjuvant properties and providing support for the hypothesis generated through the technical investigation that leachates were capable of enhancing the immune response to rHuEPO.

Adjuvants, Immunologic↗
PubMed2004

Reduction of metal leaching in brown coal fly ash using geopolymers.

Current regulations classify fly ash as a prescribed waste and prohibit its disposal in regular landfill. Treatment of the fly ash can reduce the leach rate of metals, and allow it to be disposed in less prescribed landfill. A geopolymer matrix was investigated as a potential stabilisation method for brown coal fly ash. Precipitator fly ash was obtained from electrostatic precipitators and leached fly ash was collected from ash disposal ponds, and leaching tests were conducted on both types of geopolymer stabilised fly ashes. The ratio of fly ash to geopolymer was varied to determine the effects of different compositions on leaching rates. Fourteen metals and heavy metals were targeted during the leaching tests and the results indicate that a geopolymer is effective at reducing the leach rates of many metals from the fly ash, such as calcium, arsenic, selenium, strontium and barium. The major element leachate concentrations obtained from leached fly ash were in general lower than that of precipitator fly ash. Conversely, heavy metal leachate concentrations were lower in precipitator fly ash than leached pond fly ash. The maximum addition of fly ash to this geopolymer was found to be 60wt% for fly ash obtained from the electrostatic precipitators and 70wt% for fly ash obtained from ash disposal ponds. The formation of geopolymer in the presence of fly ash was studied using 29Si MAS-NMR and showed that a geopolymer matrix was formed. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) imaging showed the interaction of the fly ash with the geopolymer, which was related to the leachate data and also the maximum percentage fly ash addition.

Carbon↗
PubMed2004

Lead leachability in stabilized/solidified soil samples evaluated with different leaching tests.

Leaching tests and model calculations were performed to investigate the immobilization mechanisms of Pb and compare different leaching protocols. Stabilization/solidification (S/S) treatments reduced Pb concentrations in the toxicity characteristic leaching procedure (TCLP) leachate from 5.9 mg/L for untreated soil to less than 0.7 mg/L. The results of eight different leaching protocols show that: (1) the main factor controlling the Pb concentration in the leachate is the final pH; (2) the final pH is a function of the leachant acidity; and (3) for a given final pH, the type of leachant has a relatively minor effect on leachability. The diffuse layer adsorption model, aqueous and precipitation reactions were employed in the MINTEQA2 program to describe the Pb leaching behavior. Both leaching tests and model simulations indicate that the Pb leaching behavior can be divided into three stages based on the leachate pH: a high alkalinity leaching stage at pH > 12, where Pb formed soluble hydroxide anion complexes and leached out; a neutral to alkaline immobilization stage in the pH range of 6-12, which was characterized by low Pb leachability caused by adsorption and precipitation; and an acid leaching stage with pH < 6, where the acid neutralizing capacity (ANC) of the S/S materials was totally consumed and therefore free Pb-ion leached out.

Adsorption↗
PubMed2005

Adsorption of trace elements from poultry litter by montmorillonite clay.

Poultry litter (PL) is used as fertilizer on agricultural lands because of its high nutrient content. However, the litter also contains trace elements such as As, Cd, Cu, Pb, and Zn. On land application of PL, these trace elements may be absorbed by crops, leach into groundwater, or enter the aquatic system as run-off. The objective of this research was to study the effect of the addition of montmorillonite clay-mineral (CM) in reducing the release of trace elements from PL. Cd, Cu, and Zn showed significant decreases of 29, 34, and 22%, respectively, in PL aqueous leachate (compared with the control-PL without CM) on mixing with 0.05 g CM but no change in As, Co, and Cr concentrations was observed. Lead showed a significant increase in PL aqueous leachate on mixing with 0.2 g CM but Pb concentration was two orders of magnitude less than in CM aqueous leachate alone. On washing, the settled precipitate (PL+CM) in the centrifuge tubes with water (desorption study) most of the adsorbed metals (Cd 85%, Cu 61%, and Zn 100%) were released. The results of this study show that the addition of CM resulted in significant adsorption of Cd and Cu from PL.

Adsorption↗
PubMed2006

Nitrogen removal in the bioreactor landfill system with intermittent aeration at the top of landfilled waste.

High ammonia concentration of recycled landfill leachate makes it very difficult to treat. In this work, a vertical aerobic/anoxic/anaerobic lab-scale bioreactor landfill system, which was constructed by intermittent aeration at the top of landfilled waste, as a bioreactor for in situ nitrogen removal was investigated during waste stabilization. Intermittent aeration at the top of landfilled waste might stimulate the growth of nitrifying bacteria and denitrifying bacteria in the top and middle layers of waste. The nitrifying bacteria population for the landfill bioreactor with intermittent aeration system reached between 10(6) and 10(8) cells/dry g waste, although it decreased 2 orders of magnitude on day 30, due to the inhibitory effect of the acid environment and high organic matter in the landfilled waste. The denitrifying bacteria population increased by between 4 and 13 orders of magnitude compared with conventional anaerobic landfilled waste layers. Leachate NO(3)(-)-N concentration was very low in both two experimental landfill reactors. After 105 days operation, leachate NH(4)(+)-N and TN concentrations for the landfill reactor with intermittent aeration system dropped to 186 and 289 mg/l, respectively, while they were still kept above 1000 mg/l for the landfill reactor without intermittent aerobic system. In addition, there is an increase in the rate of waste stabilization as well as an increase of 12% in the total waste settlement for the landfill reactor with intermittent aeration system.

Aerobiosis↗