Natural attenuation and characterization of contaminants composition in landfill leachate under different disposing ages.
ABSTRACT Chemical Oxygen Demand (COD) composition in landfill leachate would vary as the disposal time extended. Leachates with different ages were collected from Laogang Refuse Landfill of Shanghai, the largest landfill in China with a placement scale of 7600 t refuse per day. To characterize COD composition in leachate, samples were size-fractioned into suspended fractions (>0.45 microm), colloid fraction (0.45 microm<fraction<1 K Da MW) and dissolved fractions (<1 KDa MW) based on the molecular weight distribution. The fractions <0.45 microm (including colloid fraction and dissolved fractions) in leachate were further divided into 6 fractions, i.e. hydrophobic bases (Ho-base), hydrophobic acids (Ho-acid), hydrophobic neutral (Ho-neutral), hydrophilic bases (Hi-base), hydrophilic acids (Hi-acid) and hydrophilic neutral (Hi-neutral). It was found that the ratio of TOC/TC in leachate decreased over time, indicating that the percentage of organic matters in leachate decreased as the disposal time extended. It was also observed that the hydrophobic fraction accounted to about 50% of the total matters presented in the fraction <0.45 microm of all leachate samples. The main components in <0.45 microm fraction were the Ho-acid, Hi-acid and Hi-base fractions. The percentage of Ho-acid in leachate decreased from 60.8% (2 a) to 43.2% (12 a). In addition, leachate with different ages was categorized into 3 phases according to the results of Principle component analysis (PCA). TOC/COD ranges of leachate in periods I, II and III were 40-54.6%, 16.9-41.3% and 10-38.9%, respectively, indicating that the COD contribution of non-carbon reduction substances increased over time in leachate. Hence, the corresponding landfill leachate treatment process should be modified according to the leachate characterization. The results obtained in this study might provide the important information for modeling, design, and operation of landfill leachate treatment systems.
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ABSTRACT: Municipal leachates are loaded with heavy metals that can contaminate surface water before discharge into a receiving body of water. The aim of this study is to evaluate the genotoxic effects of heavy metals generated by domestic waste on the common roach Rutilus rutilus in the last of the four interconnected ponds at the Etueffont landfill. We used random amplified polymorphic DNA (RAPD) since it has been shown to be a powerful means of detecting a broad range of DNA damage due to environmental contaminants. Our results show the ability of RAPD analysis to detect significant genetic alterations in roach DNA, after contamination with a set of metals contained in the landfill leachates in comparison to a roach from a non-polluted reference pond. Analysis of electrophoresis profiles indicates apparent changes such as the appearance of new bands or disappearance of bands as compared to the control. In fact, mixed smearing and laddering of DNA fragments in muscle samples support the genotoxic effects of metal deposits in the roach. This study is the first evidence found via the RAPD-PCR technique in the detection of pollutant impacts on fish exposed to landfill leachates.Ecotoxicology and Environmental Safety 01/2014; 101:90–96. · 2.20 Impact Factor
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ABSTRACT: Environmental monitoring of leachate quality from an open municipal solid waste dumping site in Tunceli, Turkey was studied in this research. The most commonly examined pollution parameters were determined on a seasonal basis. The annual average 5-day biological oxygen demand (BOD5) and chemical oxygen demand (COD) values of station points were measured as 70 and 425 mg/L, respectively, and also the average BOD5/COD ratio (a measure of biodegradability) was calculated as 0.20. The low ratio of biodegradability and slightly alkaline pH values in the leachate samples indicated that the site was characterized by methanogenic conditions. The mean ammonium-nitrogen (NH4 (+)-N) and corresponding phosphate (orthophosphate) values were assayed as 70 and 11 mg/L, respectively. The average solids content in the leachates was measured as 4,681 mg/L (total solids) and 144 mg/L (suspended solids). Very low concentrations of iron, manganese, copper, and zinc in the leachate samples were found and the concentration of cadmium was measured below detection limits. Excessive amount of nutrients and high organic and inorganic pollutant content in the leachates pose serious pollution potential to the environment. Since no drainage system or bio treatment exists in this open dumping site, high permeability of natural soil at the site and in the surrounding area and very fractured and crackled rocks under natural soil are indicators of high groundwater pollution potential in this site.Environmental Monitoring and Assessment 12/2014; · 1.68 Impact Factor
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ABSTRACT: The final discharge point for collected landfill leachates is frequently the local municipal wastewater treatment facility. The salinity, color, nutrient, and anthropogenic organics contamination of leachates often necessitate some form of pre-treatment. When advanced oxidation processes (AOPs) are considered for pre-treatment, the unique composition of dissolved organic matter (DOM) and the relatively high concentrations of some inorganic solutes in leachate will inhibit treatment efficiency. The most important benchmark for design of AOPs is the expected steady-state production of free radical (OH). Without a quantitative assessment of total OH consumption in high-strength waste water, like a landfill leachate, efficient AOP treatment is uncertain. For this reason, two landfill leachates, distinct in color, DOM, and age of landfill, were characterized for OH-scavenging using an established competition kinetics method. After stripping the samples of inorganic carbon, the DOM in leachate from mature (stabilized) landfill was found to react with OH at a rate of 9.76 × 10(8) M(-1)s(-1). However, DOM in leachate from newer landfill was observed to scavenge available OH at a faster rate (8.28 × 10(9) M(-1)s(-1)). The combination of fast rate of reaction with OH and abundance of DOM in the sampled leachate severely limited the contribution of OH to degradation of an O3- and OH-labile organic probe compound (bisphenol-a) in oxidized mature leachate (fOH = 0.03). Substantial dosing of both O3 and H2O2 (>70 mg/L and >24 mg/L, respectively) may be required to see at least 1-log-removal (>90%) of an OH-selective leachate contaminant (i.e., parachlorobenzoic acid) in a mature landfill leachate.Water Research 03/2014; 56C:148-155. · 4.66 Impact Factor