inorganic contaminants also follow the trend of decreasing concentrations with increasing leachate age and stability. In general, leachate generated from young acidogenic landfills are characterized by high concentrations of organic and inorganic pollutants (Calli et al. 2005). The presence of Magnesium in the leachate is due to the dis- posal of construction waste along with MSW (Al-Yaqout 2003). The calcium and magnesium concentrations exhib- ited typical trends of constituents affected by the biological activity in the dumping site.
A reduction with time is attributed to the depletion of these compounds and to the increase in pH, thus reducing their solubility in leachate, and enhancing precipitation. The initial concentrations of these parameters are on the higher side (1,200–3,000 mg/L, 250–1,500 mg/L). A decrease in concentration was observed in stabilized leachate samples. The chloride concentration in the leachate varied from 1,000 to 8,000 mg/L for young leachate samples and 1,000–6,500 mg/L for stabilized samples. The possible anthropogenic sources of chloride are kitchen wastes from households, restaurants, and hotels.
A reduction with time is attributed to the depletion of these compounds and to the increase in pH, thus reducing their solubility in leachate, and enhancing precipitation. The initial concentrations of these parameters are on the higher side (1,200–3,000 mg/L, 250–1,500 mg/L). A decrease in concentration was observed in stabilized leachate samples. The chloride concentration in the leachate varied from 1,000 to 8,000 mg/L for young leachate samples and 1,000–6,500 mg/L for stabilized samples. The possible anthropogenic sources of chloride are kitchen wastes from households, restaurants, and hotels.
TA varies between 4,500 and 26,000 mg/L. The presence of high BOD (43,328 mg/L) and COD (75,840 mg/L) indicates the high organic strength. This indicates that majority of the organic compounds is biodegradable (Fatta et al. 1999). The pres- ence of Fe (400 mg/L) in the leachate sample indicates that steel scraps are also dumped in the landfill. The dark brown color of the leachate is mainly attributed to the oxidation of ferrous to ferric form and the formation of ferric hydroxide colloids and complexes with fulvic/humic substance (Chu et al. 1994). The concentration
range of trace elements such as Cd, Cu, Fe, Mn, Pb, and Zn were found in the collected
leachate samples and are also reported in Table 2. Fresh leachate samples showed a higher degree of metal solubi- lization, due to lower pH values caused by the biological production of organic fatty acids. As the dumping site age increased, the consequent increase in pH values caused a certain decrease in metal solubility (Mohan and Gandhi- mathi 2009). The stabilized leachate samples have less concentration when compared to fresh leachate samples. The concentration of Zn (4.80 mg/L) in the leachate shows that the dumping site receives waste from batteries and fluorescent lamps.
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