Characterization, risk assessment, and potential utilization of fly ash from PLTSa Merah Putih at Bantargebang, Bekasi, Indonesia

Abstract

Municipal solid waste incineration (MSWI) has been adopted in Indonesia to reduce the volume and mass of municipal solid waste. However, as a by-product of waste combustion, fly ash generation cannot be avoided. It can cause an environmental problem if not managed properly. Hence, this study aims to investigate the characteristics of fly ash generated from Indonesia’s first waste-to-energy incineration pilot plant and its potential utilization. Fly ash was characterized using X-Ray fluorescence (XRF), BET surface area measurement, pore size distribution (PSD), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS), and X-ray diffraction (XRD). The characterization results showed that calcium was predominant, around 28%, followed by titanium, silica, iron, and aluminum, with values of 7.10%, 5.70%, 4.40%, and 4.30%, respectively. These results demonstrated that MSW incineration fly ash was classified as a very active high-calcium fly ash. The surface structure of fly ash was flaky and complex, with some irregular material. The particle size distribution of fly ash shows that the diameters of most particles were nearly 12 μm. The specific surface area of fly ash was 3.06 m2/g, the total-pore volume was 0.01 cm3/g, and the average pore size was 11.82 nm. In addition, the environmental risk assessment was evaluated using the toxicity characteristic leaching procedure (TCLP). TCLP concentrations of heavy metals, including arsenic, barium, beryllium, cadmium, chromium hexavalent, copper, lead, mercury, nickel, selenium, and zinc, were lower than the regulatory level, indicating a low environmental risk. Therefore, it has great potential for utilization as a paving block mixture material.