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PubMed2001

Comparison of two biological treatment processes using attached-growth biomass for sanitary landfill leachate treatment.

The objective of this investigation was to compare two biological systems using attached-growth biomass, for treatment of leachates generated in a typical municipal solid waste sanitary landfill. A moving-bed biofilm process, which is a relatively new type of biological treatment system, has been examined. It is based on the use of small, free-floating polymeric (polyurethane) elements, while biomass is being grown and attached as biofilm on the surface of these porous carriers. A granular activated carbon (GAC) moving-bed biofilm process was also tested. This method combines both physico-chemical and biological removal mechanisms for the removal of pollutants. The presence of GAC offers a suitable porous media, which is able to adsorb both organic matter and ammonia, as well as to provide an appropriate surface onto which biomass can be attached and grown. A laboratory-scale sequencing batch reactor (SBR) was used for the examination of both carriers. The effects of different operation strategies on the efficiency of these biological treatment processes were studied in order to optimize their performance, especially for the removal of nitrogen compounds and of biodegradable organic matter. It has been found that these processes were able to remove nitrogen content almost completely and simultaneously, the removal of organic matter (expressed as BOD5 and COD), color and turbidity were sufficiently achieved.

Biodegradation, Environmental↗
PubMed2002

Landfill leachate treatment by a coagulation-photooxidation process.

This experimental study was conducted to investigate the effect of treatment of landfill leachate by a coagulation-photooxidation process. The effects of different dosages of coagulant and different pH values on the coagulation processes were compared. The effect of different concentrations of sodium oxalate (Na(2)C(2)O(4)) on the treatment process was also studied after the coagulation was performed using FeCl(3).6H(2)O. The experimental results show that in the pH range of 3-8, the lower the pH value, the higher the efficiency of the treatment. A 24% removal of COD (chemical oxygen demand, mg(O(2)) x l(-1)) can be attained by the addition of 1000 mg x l(-1) FeCl(3). A 31% removal of COD can be attained after 4h of irradiation alone, and a 64% removal of COD can be attained after 4h irradiation at pH 3 with the addition of 500 mg x l(-1) FeCl(3).6H(2)O.

Chlorides↗
PubMed2002

Effect of hydraulic retention time on inorganic nutrient recovery and biodegradable organics removal in a biofilm reactor treating plant biomass leachate.

A fixed-film (biofilm) reactor was designed and its performance was determined at various retention times. The goal was to find the optimal retention time for recycling plant nutrients in an advanced life support system, to minimize the size, mass, and volume (hold-up) of a production model. The prototype reactor was tested with aqueous leachate from wheat crop residue at 24, 12, 6, and 3 h hydraulic retention times (HRTs). Biochemical oxygen demand (BOD), nitrates and other plant nutrients, carbohydrates, total phenolics, and microbial counts were monitored to characterize reactor performance. BOD removal decreased significantly from 92% at the 24 h HRT to 73% at 3 h. Removal of phenolics was 62% at the 24 h retention time, but 37% at 3 h. Dissolved oxygen concentrations, nitric acid consumption, and calcium and magnesium removals were also affected by HRT. Carbohydrate removals, carbon dioxide (CO2) productions, denitrification, potassium concentrations, and microbial counts were not affected by different retention times. A 6 h HRT will be used in future studies to determine the suitability of the bioreactor effluent for hydroponic plant production.

Bacteria, Aerobic↗
PubMed2004

Isolation of aryl-phosphate ester-degrading bacterium from leachate of a sea-based waste disposal site.

An aryl-phosphate ester (APE)-degrading bacterium was isolated from the leachate of a sea-based waste disposal site. The isolated APE-degrading bacterial strain YS-57 grew well in a medium containing glucose and NaCl, and degraded two types of APE:tricresyl phosphate and triphenyl phosphate. The optimal temperature, pH, and NaCl concentration for the growth of strain YS-57 were 30 degrees C, 7.0, and 1.0%, respectively. Strain YS-57 grew at an APE concentration of 25 mg/l without being inhibited. APEs were degraded by the supernatant of the medium in which strain YS-57 was cultured, suggesting that the APE-degrading enzyme was released into the extracellular space in the logarithmic growth phase. The 16S rDNA sequence of strain YS-57 showed 95.6% similarity to that of Roseobacter gallaeciensis and the morphological properties were also comparable. Consequently, strain YS-57 was closely related to the genus Roseobacter.

Journal Article↗
PubMed1999

Selective determination of aromatic sulfonates in landfill leachates and groundwater using microbore liquid chromatography coupled with mass spectrometry.

Aromatic sulfonates (AS) are large-volume chemicals used in many technical processes of, for instance, the textile industry or construction. A LC/MS method for the selective determination of AS in environmental samples, based on a single-quadrupole MS, was developed and validated. The central point of this technique is the use of the compound-specific fragment ion SO3.- as marker for aromatic sulfonates. This negatively charged SO3 radical, together with the fact that AS undergo loss of SO2, allows screening for AS in complex matrixes, even in the presence of sulfate anions. Calibration curves generated from LC/MS data showed good linearity over 3 orders of magnitude, with an absolute limit of detection of approximately 1 ng. The relative standard deviation for mean areas obtained from reconstructed ion chromatograms ranged from 2.9 to 8.6%. Unlike UV detection, this LC/MS method gives similar response for both naphthalene- and benzene-sulfonates. The method presented was successfully applied to landfill leachates and groundwater, downstream of a landfill. Furthermore, this technique allowed identification of an unknown AS found in drain samples.

Chromatography, High Pressure Liquid↗
PubMed2003

Terpenoids as major precursors of dissolved organic matter in landfill leachates, surface water, and groundwater.

13C NMR analyses of hydrophobic dissolved organic matter (DOM) fractions isolated from a landfill leachate contaminated groundwater near Norman, OK; the Colorado River aqueduct near Los Angeles, CA; Anaheim Lake, an infiltration basin for the Santa Ana River in Orange County, CA; and groundwater from the Tomago Sand Beds, near Sydney, Australia, found branched methyl groups and quaternary aliphatic carbon structures that are indicative of terpenoid hydrocarbon precursors. Significant amounts of lignin precursors, commonly postulated to be the major source of DOM, were found only in trace quantities by thermochemolysis/gas chromatography/mass spectrometry of the Norman Landfill and Tomago Sand Bed hydrophobic DOM fractions. Electrospray/tandem mass spectrometry of the Tomago Sand Bed hydrophobic acid DOM found an ion series differing by 14 daltons, which is indicative of aliphatic and aryl-aliphatic polycarboxylic acids. The product obtained from ozonation of the resin acid, abietic acid, gave a similar ion series. Terpenoid precursors of DOM are postulated to be derived from resin acid paper sizing agents in the Norman Landfill, algal and bacterial terpenoids in the Colorado River and Anaheim Lake, and terrestrial plant terpenoids in the Tomago Sand Beds.

Bacteria↗
PubMed2006

Strontium speciation during reaction of kaolinite with simulated tank-waste leachate: bulk and microfocused EXAFS analysis.

Radioactive strontium (90Sr) is an important constituent of the complex wastes from past nuclear weapons production and has been stored in underground tanks at U.S. DOE sites (e.g., Hanford, WA). Using bulk and microfocused EXAFS spectroscopy, we examined temporal changes in solid-phase Sr speciation in kaolinite samples reacted for 1-369 d with high-pH, high ionic strength synthetic tank-waste leachate containing Sr(2+) and Cs(+) at 10(-3) mol kg(-1). Analyses of bulk EXAFS spectra showed that Sr initially forms a precipitate by 7 d with a local structure similar to SrCO(3-) (s). At 33 d, microfocused EXAFS of individual particles in one sample revealed a mixture of hydrated and dehydrated Sr associated with neoformed sodalite-type phases. At aging times of 93 d and longer, bulk EXAFS spectra and supporting characterizations indicated nonexchangeable Sr with a local structure consistent with incorporation into increasingly crystalline aluminosilicate particles, particularly sodalite. These experimental studies suggest that irreversible trapping of radionuclides occurs if they are present during the formation and aging of feldspathoid alteration products of local Si-bearing sediment minerals. This may serve as an effective contaminant sequestration mechanism at sites such as Hanford.

Carbonates↗
PubMed2006

Predicting uncertainty in the ecotoxicological assessment of solid waste leachates.

Environmental managers need suitable technological methods to use in optimization studies to improve management of hazardous waste. One of the challenges to achieving a reliable hazardous waste classification is the improvement of procedures used forthe ecotoxicological characterization of solid waste leachates. Indeed, this step requires data that meet levels of acceptable quality if scientifically based decisions are to be made. In this study, we illustrate how the variability associated with the successive steps of a procedure used to assess ecotoxicological hazard of solid waste (i.e., primary sampling, laboratory sampling, toxicity measurements) can contribute to the overall variability of the ecotoxicity results. To this end, a municipal solid waste incinerator bottom ash and a slag from a second smelting of lead were studied using a nested experimental design. The results showed that the waste sampling design is of major importance for limiting the final variability of toxicity test parameters. At the opposite, increasing the number of replicates at the toxicity test level has negligible impact on this variability. Our approach could be of great practical interest in ecotoxicological studies not only for ensuring a safe classification for these materials, but also for improving sampling protocols and facilitating less time-consuming and less expensive ecotoxicological evaluations.

Ecology↗
PubMedDate not supplied

An environmental health survey of drinking water contamination by leachate from a pesticide waste dump in Hardeman County, Tennessee.

Ground water that was used as a source of potable water by residents of a small community became contaminated by leachate from a 300,000 barrel pesticide waste dump. An environmental health survey of the residents and an apparent control group was conducted to determine if any adverse health effects resulting from exposure to the toxic compounds, many of which were hepatotoxins, could be detected. The survey utilized a health questionnaire, a clinical examination, and a biochemical screening. The latter included analysis of serum for liver and kidney function parameters, determination of hepatitis A and B serology, and bile acid determinations on fasting and postprandial serum and urine specimens. Air and water from representative homes and urine from study participants were analyzed for selected organic compounds. The biochemical screening was conducted on two occasions 2 months apart. The initial hepatic profile testing revealed elevated concentrations of the serum enzymes, alkaline phosphatase and serum glutamic oxaloacetic transaminase, in residents who had used the contaminated water. During follow-up testing of these same persons 2 months later, these values were significantly reduced, as were postprandial serum concentrations of the bile acid of cholyglycine. Six individuals in the exposed group had slight hepatomegaly compared to one individual in the intermediate exposure group and none in the controls. Concentrations of carbon tetrachloride were as high as 18,700 microgram/L in the well water samples. The biochemical and clinical observations are suggestive of a transitory liver injury probably related to exposure to the contaminated drinking water.

Adolescent↗
PubMed2002

Airway hyperresponsiveness caused by aerosol exposure to residual oil fly ash leachate in mice.

Particulate air pollution is associated with exacerbation of asthma and other respiratory disorders. This study sought to further characterize the pulmonary effects of residual oil fly ash (ROFA), an experimentally useful surrogate for combustion-derived particulates in ambient air. Mice were exposed to aerosols of the soluble leachate of residual oil fly ash (ROFA-s). Physiologic testing of airway function (non invasive plethysmography) showed increased Penh, an index of airway hyperresponsiveness (AHR), in a time- and dose-dependent manner after exposure to ROFA-s. BAL analysis showed a minor influx of neutrophils, which was maximal at 12 h after exposure and essentially resolved by the time point of maximal AHR (48 h after exposure). The AHR caused by ROFA-s was reproduced by a mixture of its major metal components (Ni, V, Zn, Co, Mn, Cu) but not by any individual metal alone. Systemic pretreatment of mice with the antioxidant dimethylthiourea abrogated ROFA-s-mediated AHR. Analysis of mice of varying ages showed that ROFA-s had no marked effect on airway responsiveness of 2-wk-old mice, in contrast to the AHR seen in 3- and 8-wk old mice. ROFA-s-mediated AHR was unchanged in neurokinin 1 receptor knockout mice and in mice treated with an neurokinin antagonist, arguing against a role for this mediator in ROFA-s-mediated effects. Data indicate that ROFA-s mediates AHR in mice through antioxidant-sensitive mechanisms that require multiple metal constituents. Maturational differences in susceptibility to ROFA-induced AHR may be useful for further studies of mechanisms of particle effects.

Aerosols↗
PubMed2001

Prediction of metal precipitates in tannery sludge leachate based on thermodynamic calculations.

Thermodynamic calculations were performed in order to predict the formation of metal precipitates during the tannery sludge leaching. Gibbs free energy deltaG=RTln(Qc/Kc) of precipitation reaction was used to examine the formation of precipitates during the leaching process. The values of activity equilibrium constant (Ka) of various precipitation reactions were adopted from the literature. The Ka values were corrected to obtain the corresponding values of concentration product (Qc) and concentration equilibrium constant (Kc) using the activity coefficients (gamma) of the ions. The activity coefficients (gamma) of the ions was calculated using Davies equation Lngammai=-1.172Zi2((I0.5/(1+I0.5))-0.3I) (aqueous solution, 25 degrees C, 1 atm, I>0.3 mol x l(-1)). The values of ionic strength (I) at different sludge solids concentration and leaching pH were obtained by measuring the concentration of all ionic species in the leachate. The thermodynamic calculations indicated that the possible metal precipitates formed during the leaching process were (am)Cr(OH)3, (am)CrPO4, (am)Fe(OH)3, alpha-FeOOH(goethite), FePO4.2H2O, (am)AIPO4-2H2O, CaSO4.2H2O(gypsum). The solubility of these precipitates was found to decrease with the increase in the ionic strength (or sludge solids concentration). The results of computations were supported by the experimental observations.

Chemical Precipitation↗
PubMed2004

Startup of an anaerobic fluidized bed reactor for landfill leachate treatment.

Anaerobic treatment of the young landfill leachate in a pilot-scale fluidized bed reactor was performed to observe the effects of startup on COD removal, biogas production and biomass attachment. During the experiments, the organic loading rate (OLR) was increased gradually from 2.5 to 27 g COD l(-1) day(-1) with varying the feed rate and the hydraulic retention time in the range of 5.5-13 1 day(-1) and 1-2.35 days, respectively. The anaerobic fluidized bed reactor (AFBR) showed an excellent performance and attained steady state conditions with COD removal of 90% after 80 days. Biogas production in the reactor continuously increased and its average yield (Y(gas)) was defined as 0.531 biogas g(-1) COD(rem)(-1) with a correlation of 99%. Greater microbial attachment was found at the increased loading rates and the attached biomass concentration (X(attach)) consisted of about 90% of the total biomass concentration. In addition, the substrate utilization rate indicated a linear increase as a function of time during the process.

Bacteria, Anaerobic↗
PubMed2007

Removal of heavy metals from synthetic leachate using a biologically generated electric field.

Removal of heavy metals from aqueous solutions was investigated in batch reactors using a biologically generated electric field. An electric field with a potential difference of 50 mV to 100 mV was generated using an anaerobic culture and an aerobic culture couple. The electric field was applied to a synthetic leachate solution made up using cadmium, zinc or nickel salts using titanium-coated mesh electrodes. After 72 hours of exposure, at 15 mm electrode spacing, less than 40% removal of cadmium and zinc was observed while nearly 80% nickel removal occurred. After 72 hours and at an electrode spacing of 25 mm, nearly 40% removal of cadmium occurred, 60% of zinc was removed, and 80% of nickel was removed from solution. After 72 hours and at 45 mm electrode spacing, nearly 70% of cadmium, 60% of zinc, and over 80% of nickel was removed. The tendency for zinc and cadmium to form more hydroxy complexes as compared to nickel may have contributed to these results. Cadmium and zinc removal were lower at an electrode spacing of 15 mm and 25 mm, compared to removal at an electrode spacing of 45 mm. Electrode spacing did not affect nickel removal.

Bioreactors↗
PubMed2001

Biosorption of heavy metals from landfill leachate onto activated sludge.

The removal of various heavy metals was studied when activated sludge was exposed to heavy metals in landfill leachate. Batch uptake tests were conducted for this purpose. Adsorption was the main mechanism of removal when biomass was contacted with heavy metals. Activated sludge had a high biosorption capacity and equilibrium was reached in a short time with respect to copper, iron, manganese, zinc and chromium. Adsorption isotherms were generated for those heavy metals and the Freundlich constants were calculated. Among the metals studied, manganese became very concentrated on activated sludge with time.

Absorption↗
PubMed2001

Ammonia removal from composting leachate using zeolite. I. Characterization of the zeolite.

The effects of ammonium concentrations, contact time, and zeolite particle sizes on the ammonium adsorption capacities of a Canadian zeolite were studied using batch experiments. Both the rates and capacities of ammonium adsorption increased with increased concentrations of ammonium in solution. Ammonium adsorption increased significantly with decreasing zeolite particle size for all tests and the adsorption capacities ranged from 14.35-17.81 mg N/g. Also, ammonia adsorption increased with contact time, and it occurred rapidly at the beginning of contact, and then gradually decreased as time progressed. Langmuir isotherm best describes the equilibrium of ammonia adsorption on zeolite. Particle diffusion was the rate-controlling mechanism for the first 4 h of contact. In spite of competition potassium ions, zeolite has shown a great potential for ammonia removal from composting leachates.

Adsorption↗
PubMed2003

Fenton-like oxidation of landfill leachate.

The treatment of stabilized leachates by means of Fenton's like reagent [Fe(III)-H2O2] has been studied. It has been demonstrated that the oxidation state of the catalyst does not influence the efficacy of the process in terms of chemical oxygen demand depletion profiles. The abrupt increase in temperature experienced in oxidation experiments involves a wastage of hydrogen peroxide diminishing the fraction of this reagent addressed at removing COD. If temperature is kept constant, the hydrogen peroxide uptake is 10 mg of H2O2 consumed per mg of COD abated (from 15 to 30 degrees C). Working temperatures above 30 degrees C does not lead to additional COD conversion, contrarily, the percentage of wasted H2O2 is increased. A rough economic analysis of the process indicates that this treatment can be a suitable alternative to deal with this type of effluents.

Hydrogen Peroxide↗
PubMed2003

Molecular analysis of microbial communities in nitrification and denitrification reactors treating high ammonia leachate.

Molecular analysis of microbial populations in two bench-scale nitrification and denitrification reactors fed with high ammonia landfill leachate was conducted in this study by using DGGE, cloning, and FISH techniques in addition to classical efficiency control parameters. Nitrification tank was operated with a computer-controlled alkalinity dosing system to supply the alkalinity intermittently as consumed on the basis of on-line pH monitoring. By keeping the pH at 7.0 with this system, 99% nitrification efficiency and rates of about 0.14-0.18 mgNH4+-N/mgVSSday were obtained. Meanwhile, as ammonia oxidizing bacteria Nitrosomonas and Nitrosococcus mobilis-like cells and as nitrite oxidizing bacteria Nitrobacter-related cells were intensively indicated. Moreover, some aerobic denitrifiers as Thauera species were also identified. After the termination of pH adjustment in the preceding anaerobic reactors, nitrification tank was loaded with more biodegradable COD as a result of reduced COD removal in anaerobic reactors. Microbial diversity was immediately affected from this alteration and heterotrophic carbonaceous bacteria and aerobic denitrifiers have dominated. To provide the former high efficiencies, retention time has increased from 24 to 48 h and a second pump dosing HCl was included to the automatic control system. Subsequent to these precautions, numbers of ammonia (Nso190) and nitrite oxidizing bacteria (NIT3) were comparatively increased. In denitrification system, about 98% denitrification efficiencies were obtained at 2000 mg/L NOx-N concentrations if sodium acetate was supplied as carbon source. Meanwhile, with 20 gVSS/l biomass concentration, denitrification rates of about 1.34 mgNOx-N/mgVSSday were obtained. All sludge samples have represented similar DGGE patterns and Paraccoccus-related species were identified as dominant denitrifying bacteria.

Ammonia↗
PubMed2004

Indications of hormonally active substances in municipal solid waste leachate: mobilization and effect studies from Sweden and Norway.

Several species of fish from a freshwater lake downstream a landfill in central Sweden have been found to be exposed to specific endocrine active substances (EAS), possibly able to interact with important functions in the synthesis of steroids and thereby disrupting a normal development of the gonad. A preliminary study of 7 streams and lakes in Norway showed that female perch have a significant reduction in gonad somatic index (GSI) with fish length and weight at one location. This can be an indication of disturbance due to exposure of hormonally active agents over time. Only 2 locations showed significantly difference in GSI and liver somatic index (LSI). Possible explanations can be that the necessary combination between exposure and exposed is exclusive and does not apply in general, or that the effects are masked due to other exposures such as e.g., nutrient, organic or other chemicals, physical or biological loads. The number of sampled locations is, however, too limited to be conclusive. Liver samples are being analyzed for organic pollutants, but these analyses were not ready at the time of publication. A previous study of leachate and sediment samples indicated the presence of several organic pollutants and compounds known to be hormonally active. Investigations of extracts from sediment samples from one of the exposed lake in Sweden showed the presence of both naturally occurring and xenophobic organic compounds. In samples extracted with a base-neutral extraction the compounds 1,1 sulfonyl-bis(4-chlorobenzene) and bis-2-etylhexyl-phtalate were detected. The high lipid affinity of the phtalate correlates with the finding of the compound in the high organic content layer of 20-40 cm in the exposed sediment. Pesticide residues were not found in the samples.

Animals↗