RESUMEN
In order to elucidate the evolution mechanism of heavy metal species in landfill cells, three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM), fluorescence quenching titration and parallel factor analysis (PARAFAC) were employed to study the complexation process between Cu(â ¡) and colored dissolved organic matter (CDOM) from landfill with different ages. The experimental results indicated that the landfilled CDOM comprised protein-like, humic-like and fuvic-like matter. The relative content of protein-like matter decreased during the landfill process, whereas the humic-like and fuvic-like matter increased during the process. The range of the conditional stability constants and the percentage of fluorophores participated the complextion between Cu(â ¡) and protein-like matter with different ages were 4.00-5.75 and 22.78%-95.30%, respectively. Those parameters changed slightly for humic-like matter with different ages, which ranged from 4.71 to 5.54 and from 42.35% to 61.46%, respectively. As regard to fulvic-like matter, those parameters were 4.44-5.25 and 46.14%-57.22%, respectively. The complexation ability of humic-like substances with Cu(â ¡) decreased during the landfill process, though the percentage of fluorophores participated the complexation increased. The complexation ability of humic-like substances with Cu(â ¡) was stronger than that of fulvic-like matter, though the percentage of fluorophores participated the complexation in humic-like matter was low compared with fulvic-like matter.
RESUMEN
Samples of wastes and leachates were collected from a landfill site and a leachate treatment plant[i.e., equalization basin, anaerobic zone, oxidation ditch, and membrane bioreactor (MBR) section]. Dissolved organic matter (DOM) was extracted from the wastes and leachates, and its composition, evolution, and complexation characteristics with heavy metals were studied using UV-Visible and fluorescence spectroscopy combined with1H nuclear magnetic resonance. The aliphatic compounds were found to be the main substances in DOM in the fresh landfill wastes (<5 a), and the relative content of aromatics and substituent groups, i.e., carbonyl, hydroxyl, and carboxyl functional groups, decreased during the initial process. On the other hand, carbohydrates and organic amines were observed to be the main substances in DOM obtained from the intermediate and old landfill wastes (>5 a), and the relative content of aromatics and substituent groups (carbonyl, hydroxyl, and carboxyl functional groups) increased persistently during the process of organic matter humification. The aliphatics, carbohydrates, and organic amines all existed in DOM from the equalization basin Carbohydrates and aromatic compounds increased rapidly after the anaerobic, aerobiotic, and membrane treatment. However, low molecular weight organic matter and alkyl chain substances decreased during the leachate treatment process and the side chain of the aliphatics was shortened despite the increase in its content. The distribution of zinc in the wastes and leachates was influenced by the complexation with the nitrogen-and oxygen-containing functional groups, whose effect on other metals was not obvious.