A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering and Management Inter-University Program on Environmental Toxicology, Technology and Management.

Thesis (Ph.D.) - Asian Institute of Technology - Chulabhorn Research Institute - Mahidol University, 2008

This study aimed to evaluate the rehabilitation and mmmg potential of waste from Nonthaburi dumpsite in Thailand. The influence of heavy metal contamination was explored by conducting sequential extraction analysis and toxic characteristic leaching potential (TCLP) test on waste samples collected from dumpsite. The quality of leachate, groundwater and surface water resources in the surrounding area of dumpsite were determined. The potential toxic effect of leachate to the plant species was evaluated by seed germination and root elongation toxicity test on rice plant (Oryza sativa L) that was sensitive dominant species surrounding this study area. The excavated waste was subjected to separation process by using trommel screen with open size of 25mm and 50mm. The waste size fractions obtained were distributed as three different sizes such as < 25mm, 25-50mm and >50mm. The physical and chemical characteristics of the each waste fraction were determined to evaluate the recycling potential of mined waste from the dumpsite. The results for heavy metal concentration and sequential extraction analysis, showed high concentration and high leaching potential of Zn, Cu and Mn compared to other metals in the waste. Although the concentration of all the metal in the extracted leachate in TCLP test were below the National effluent quality standards, the possible leaching rate of Mn and Zn were high in acidic condition. The leachate quality analysis showed heterogeneity of solid waste age and the methanogenic condition of dumpsite. The basic pH value leachate illustrates the sufficient acid buffer capacity of the dumpsite to neutralize the organic acid generated from the anaerobic degradation of organic matter. Thus, the leaching of heavy metals from the dumpsite is attributed for the affinity of reducible heavy metal to be released in the reducing condition and formation of heavy metal complex with the dissolved organic compound generated from the organic matter degradation. The leachate quality in dumpsite was found to be lower than the effluent quality standard especially for BOD, COD, TKN, Cr and Cu. The surface water was found to have high contamination of leachate from dumpsite with the concentration of BOD, ammonia, Mn, Cr and Ni content above the quality standards of surface water and drinking water. In the case of ground water, the concentration of Mn, Pb and Ni was above the acceptable standard limit. Though the heavy meal concentration in the runoff leachate except for Cr were below the National effluent standards, the effect of these metals in any concentration proved to be toxic from the seed germination and root elongation toxicity test on rice (Oryza sativa L). For mining potential of waste, the major component of excavated waste analyzed was of 41 % plastics and 31 % fine particle. The screened waste of size >50mm except for high Cu and Zn concentration, this waste fraction possessed high calorific value making it suitable for RDF production. The waste fraction of size <25mm was found suitable for composting whereas the non-recyclable waste fraction 25-50mm size need to be landfilled