Natural attenuation and characterization of contaminants composition in landfill leachate under different disposing ages

School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240, PR China.
Science of The Total Environment (Impact Factor: 4.1). 02/2009; 407(10):3385-91. DOI: 10.1016/j.scitotenv.2009.01.028
Source: PubMed


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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    • "Landfill is prevalent worldwide for its simple operations and low cost, and more than 80% of municipal solid wastes (MSWs) generated in China is disposed by landfill (Lou et al., 2009). Nevertheless, landfill leads to pollution problems such as leachate and landfill gas. "
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    ABSTRACT: Dissolved organic matter (DOM) isolated from the leachates with different landfill ages was fractionated into hydrophobic acid (HOA), hydrophobic neutral (HON), hydrophobic base (HOB) fractions and hydrophilic matter (HIM) based on hydrophobicity, and the composition and degradation potential of the bulk DOM and its fractions were investigated by excitation-emission matrix fluorescence spectra coupled with parallel factor analysis. Results showed that the bulk DOM comprised fulvic-, humic-, tryptophan- and tyrosine-like substances, as well as component C1, whose composition and origin was unidentified. Landfill process increased the content of component C1, fulvic- and humic-like matter. The HON fractions comprised primarily component C1 and tyrosine-like matter. The HOA, HOB and HIM fractions isolated from the young leachates consisted mainly of tryptophan- and tyrosine-like substances. As to the intermediate and old leachates, the HOA and HOB fractions comprised mainly component C1, while the HIM comprised mainly fulvic-like matter. The HIM showed the most resistant against biodegradation among the four fractions, and was the main component of leachate treatment. Advanced oxidation and/or membrane treatment are recommended to remove the HIM fraction due to its hydrophilic and stable characteristics.
    Full-text · Article · Sep 2015 · Chemosphere
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    • "<0.01–0.3 5 Zn 0.02–2.4 0.01–0.5 0.0001–5310 86 n value number a All concentrations are in milligram per liter, unless otherwise indicated b Andreottola and Cannas 1992; Aziz et al. 2011; Bulc 2006; Chen 1996; Chu et al. 1994; Comstock et al. 2010; Cortez et al. 2010; Depountis et al. 2009; Durmusoglu and Yilmaz 2006; El-Fadel et al. 1997; Fan et al. 2006; Fan et al. 2007; Fatta et al. 1999; Gotvajn et al. 2011; Harris and Gaspar 1989; Henry et al. 1987; Huo et al. 2008; Jensen and Christensen 1999; Kang et al. 2002; Kheradmand et al. 2010; Knox 1983; Koshy et al. 2007; Kruse 1994; Kulikowska and Klimiuk 2008; Kumar and Alappat 2005; Kurniawan et al. 2006; Kylefors 2003; Lema et al. 1988; Li et al. 2010; Lin and Chang 2000; Lou et al. 2009; Marañón et al. 2006; Matthews et al. 2009; Norbu et al. 2005; Öman and Junestedt 2008; Øygard et al. 2008; Øygard et al. 2004; Pi et al. 2009; Robinson and Grantham 1988; Singh et al. 2008; Sletten et al. 1995; Srivastava and Ramanathan 2008; Tatsi and Zouboulis 2002; Trabelsi et al. 2009; Vilar et al. 2011a; Vilar et al. 2011b; Weng et al. 2010; Wiszniowski et al. 2007; Xiaoli et al. 2007; Young et al. 1986; Ziyang et al. 2009 "
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    ABSTRACT: The objective of this study was to assess the degree of long-term waste maturation at a closed landfill (Etueffont, France) over a period of 21 years (1989-2010) through analysis of the physicochemical characteristics of leachates as well as biochemical oxygen demand (BOD), chemical oxygen demand (COD), and metal content in waste. The results show that the leachates, generated in two different sections (older and newer) of the landfill, have low organic, mineral, and metallic loads, as the wastes were mainly of household origin from a rural area where sorting and composting were required. Based on pH and BOD/COD assessments, leachate monitoring in the landfill's newer section showed a rapid decrease in the pollution load over time and an early onset of methanogenic conditions. The closing of the older of the two sections contributed to a significant decline for the majority of parameters, attributable to degradation and leaching. A gradual decreasing trend was observed after waste placement had ceased in the older section, indicating that degradation continued and the waste mass had not yet fully stabilized. At the end of monitoring, leachates from the two landfill linings contained typical old leachates in the maturation period, with a pH ≥ 7 and a low BOD/COD ratio indicating a low level of waste biodegradability. Age actually contributes to a gradual removal of organic, inorganic, and metallic wastes, but it is not the only driving factor behind advanced degradation. The lack of compaction and cover immediately after deposit extended the aerobic degradation phase, significantly reducing the amount of organic matter. In addition, waste shredding improved water infiltration into the waste mass, hastening removal of polluting components through percolation.
    Full-text · Article · Sep 2015 · Environmental Science and Pollution Research
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    • "Landfills, which are the most common means of organized waste disposal, can be sources of a wide range of pollutants (Williams, 2005; Committee to Assess the Performance of Engineered Barriers, 2007; Eggen et al., 2010) because they generate leachates that can migrate through the soil and pollute surface water and groundwater (Van Breukelen, 2003; Unnisa et al., 2008; Goorah et al., 2009; Ziyang et al., 2009; Barcic & Ivancic 2010; Varank et al., 2012). In industrialized countries, over 1 kg of municipal and domestic waste is produced per day per inhabitant, and most of this waste is deposited in municipal landfills. "
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    ABSTRACT: Clays are commonly used as liners in urban landfills. However, the reactive processes with landfill leachates, and in particular the role of accessory minerals is poorly known. The aim of this work is to evaluate the diffusion of a synthetic urban landfill leachate through compacted natural smectite-illitic clays containing carbonates and sulfates and to predict the functioning of the clay liner for different minor mineral proportions. The leachate, characterized by acidic pH conditions and high organic matter content, is a typical aqueous solution formed in the acetogenic phase of organic matter degradation in urban landfill areas. Medium-scale (11 cm) laboratory diffusion tests were performed over 77 days. Chloride diffusion coefficients, porosity changes, cation exchange constants and the sulfate reduction rate were quantitatively assessed by means of reactive transport modelling. The exchange capacity of the clays is responsible for NH4 + retention. However, the presence or absence of gypsum in the initial clay rock controls the functioning of the liner. Gypsum dissolution ensures a high sulfate concentration in the porewater and enhances the acetate consumption via sulfate reduction. Gypsum dissolution and the concomitant calcite precipitation do not significantly alter the porosity of the clay rock.
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