The properties of dissolved organic matter (DOM) in the leachates discharged from lysimeters and landfill sites containing municipal solid waste incineration residues (MSWIRs) were studied. DOM samples were divided into hydrophobic acid, base, neutral (Hpo-A, Hpo-B, Hpo-N) and hydrophilic (Hpi) fractions using the fractionation method employing DAX-8 resin. Hpi was the smallest fraction of all the raw leachate samples. The proportion of Hpo-N increased with increasing operating time. Landfill sites containing abundant non-combustible wastes showed a higher proportion of Hpo-B than Hpo-A. The molecular weights and functional groups of the DOM fractions were studied by using gel permeation chromatography and FTIR, respectively. In addition, the fluorescent properties and binding sites of the DOM fractions were investigated using fluorescence analysis. In the synchronous scan spectra of each DOM fraction, most of DOM fractions showed an emission peak for the main fluorophores at around 300 nm or 350 nm, which are regarded as aromatic amino acid-like fluorophores. The interaction between the DOM fraction and the pollutants (Cu(2+), pyrene and phenanthrene) was investigated using the fluorescence quenching method. It was observed that the aromatic amino acid-like fluorophores in the DOM fractions could be an important factor affecting complexation with the pollutants.
"Studies on the interaction between metal ions and DOM are crucial for understanding the behavior and fate of metals in the environment. Seo et al. (2007) investigated the complexation process between Cu (II) and different fluorescence peaks identified from synchronousscan spectra of leachate DOM fractionation. He et al. (2010) investigated the interaction between Hg (II) and four fluorescence peaks identified by visual peak identification analysis of EEM spectra of bulk DOM in leachate, and Wu et al. (2011, 2012) characterized the complexation process between the metals (Cu (II), Pb (II), Zn (II) and Cd (II)) and different fluorescence components identified by the PARAFAC analysis of EEM spectra. "
[Show abstract][Hide abstract] ABSTRACT: Dissolved organic matter obtained from landfill leachate was separated into hydrophobic acid, base, neutral (HOA, HOB, HON) and hydrophilic (HIM) fractions. Fluorescence excitation-emission matrix spectra and parallel factor analysis were employed to characterize the composition, and fluorescence quenching titration technique was applied to study the complexation between Hg (II) and HON, HOA, and HIM fractions. Protein-like substances, humic-like compounds and xenobiotic organic matters (XOM) were identified in all fractions. The HOA, HOB and HON fractions comprised mainly XOM, while the HIM fraction consisted primarily of humic-like compounds. The complexation ability of protein-like substances was higher than that of humic-like compounds. The complexation ability of the HIM was highest for protein-like substances, while the complexation ability of the HON fraction was the highest for humic-like substances. The results suggested that the toxicity and bioavailability of the mercury in the young leachates was the highest, and decreased with landfill time.
"Hallbourg et al. (1992) investigated the organic pollutants in groundwater and surface water at three landfills in north central Florida, and they concluded that there was a lot of aromatic organic matter and many undecomposed priority organic pollutants in the water. Many studies of landfill leachate (Benfenati et al., 2003; Seo et al., 2007) have shown that there were various kinds of organic pollutants in landfill leachate, such as alkenes, aromatic hydrocarbons, acids, esters, alcohols, hydroxybenzene, aldehydes, ketones, amides, etc. Many are listed as carcinogens or otherwise toxic. "
[Show abstract][Hide abstract] ABSTRACT: A set of simultaneous aerobic and anaerobic (SAA) bio-reactor system was used for the removal of organic pollutants and ammonia in the landfill leachate generated from Datian Shan Landfill in Guangzhou, China. The influent concentrations of COD and were 1000–3300 and 80–230 mg L−1, respectively. The average effluent concentrations of COD and were 131 and 7 mg L−1, respectively. The concentrations of COD and had reached the Chinese second grade effluent standard (COD < 300 mg L−1, < 25 mg L−1) for this kind of wastewater. Gas chromatogram–mass spectrum (GC/MS) analysis was used to measure the organic pollutants in the landfill leachate. About 87 organics were detected in this landfill leachate, and 16 of them belong to the list of environmental priority pollutants established by the US Environmental Protection Agency. About 31 of the 87 organic pollutants were completely removed by the SAA bio-reactor, the concentrations of further 14 organic pollutants were reduced by more than 80%, and the removal efficiencies of the other 25 organic pollutants were over 50%.
[Show abstract][Hide abstract] ABSTRACT: Dissolved organic matter (DOM) in leachate from landfills of three different ages (0, 5, and 10 year) was partitioned into hydrophobic acid, hydrophobic neutral, and hydrophilic matter fractions using the fractionation method employing XAD-8 resin. The spectroscopic characteristics of these fractions were determined through constant-wavelength synchronous fluorescence spectrometry (CWSFS). The interaction characteristic of phenanthrene with these fractions was determined through the fluorescence quenching method and CWSFS. The results revealed that the composition of DOM became complex with the increase in landfill age. The partition coefficients (K
doc) for the three DOM samples of different landfill ages are in the order 10 a DOM > 5 a DOM > 0 a DOM. The hydrophobic fraction showed the highest K
doc value among the DOM fractions. Lower linearity Stern–Volmer plots were observed in 10 a DOM and its hydrophobic fractions. CWSFS spectra showed that a special site was fully occupied with the addition of the quencher. Desorption was found in some fractions. Therefore, CWSFS is a sensitive tool for the detection of DOM-polycyclic aromatic hydrocarbon interaction.
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