Bottom ash is a part of by-product from the municipal solid waste power plants which is always a wider problem for the urban and rural communities due to its disposal plants may cause serious environmental pollution. This work was focused on the residual heavy metal in an incinerator bottom ash from the municipal waste power plant placed in Nongkham district, Bangkok. Four bottom ash samples were obtained in 2017. After drying and grounding, the bottom ash samples were prepared to clear solution with the microwave digestion technique using nitric, hydrochloric and hydrofluoric acid under the heating program. The total residual heavy metals in the incinerator bottom ashes, such as lead, copper, zinc, and cadmium were determined by using flame atomic absorption spectrophotometer (FAAS) with deuterium background correction. The total concentration of lead, copper, zinc and cadmium were found in the range of 280.40-354.22mg kg-1, 365.35-524.45 mg kg-1, 1,527.25-2,074.34 mg kg-1, and 0.48-1.02 mg kg-1, respectively. The recovery of all metals was found in the range of 89.4-101.2% and the relative standard deviation (RSD) was to be 2.15-3.55 % (n=7). The concentration of zinc, copper, and lead was found high levels, while cadmium was low concentration. Heavy metals in solid waste material occur in different chemical forms and phases. The sample preparation based on the microwave digestion was successfully developed for the waste samples with a good reliability.
