Abstract
Solid waste production is rapidly increasing in Bangladesh and landfill leachate is the consequence of the decomposition of this waste. These leachates contain heavy metals and significant amount of dissolved organic matter (DOM). DOM is known to have considerable role in heavy metals speciation. Hence, it is important to characterize DOM/leachate and evaluate toxic metals binding affinity of DOM. The objectives of this study were to characterize the DOM in landfill leachate through physico-chemical and optical analyses and to investigate the toxic metals (Ni2+, Pb2+ and Hg2+) binding affinity of three different ages (fresh sample L-1, young sample L-2 and mature sample L-3) DOM samples. Results suggested that leachate is a potential pollutant which contained very high organic pollutant load. Conditional stability constant (LogK) and percentages of fluorophores that correspond to metal binding (%f) values indicated that young DOM sample (L-2) had the highest binding affinity to all the three metals ions. In general, DOM samples showed the following order affinity to the metal ions; Ni2+ binding affinity: L-2 > L-3 > L-1, Pb2+ binding affinity: L-2 > L-3 > L-1 and Hg2+ binding affinity: L-2 > L-1 > L-3.
Highlights
Solid waste management has become a tremendous work for densely populated developing country due to the huge production rate of wastes and poor management infrastructure
The socio-economic situations of the country are mounting through fast industrialization and urbanization, so the amount of solid waste generation will continue to increase in future (Ahmed and Ali 2006)
In composition, dissolved organic matter (DOM) is a major fraction of leachate which contributes more than 85% of total organic matter in terms of organic carbon in leachates (Zhang et al 2009)
Summary
Solid waste management has become a tremendous work for densely populated developing country due to the huge production rate of wastes and poor management infrastructure. Bangladesh is one of the rapidly developing countries with very dense population and poor waste management facilities in its major cities. The socio-economic situations of the country are mounting through fast industrialization and urbanization, so the amount of solid waste generation will continue to increase in future (Ahmed and Ali 2006). High concentrations of heavy metals are found in the landfill leachate of Bangladesh. Several factors could contribute for the heavy metal input in landfill leachate. About 2.8 million metric tons of electronic wastes containing mercury (Hg) and lead (Pd) are generated each year which are disposed to landfills, agricultural land and water bodies (EDSO 2010). The presence of heavy metals in fertilizers (Yusuf et al 2003; Naser et al 2009) and
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