Feasibility study of manufacturing fired brick from municipal solid waste incinerator Ash

Abstract

The possibility of recycling the incinerated municipal solid waste (IMSW)bottom ash by its incorporation in structural bricks was investigated. This study starts with the collection and incineration of the municipal solid waste. Then physical and chemical characterizations of the IMSW ash were done. Finally these ashes were used as a major constituent to make the brick. In this purpose, 0 to 50% (by weight) IMSW ash was mixed with the normal clay. This study constitutes of observation of particle size and particle size distribution, determination of chemical composition by chemical analysis and x-ray fluorescence spectroscopy (XRF), determining the compounds present by x-ray diffractometry (XRD), etc. of the incinerated ash. It was found that the analysis of particle size distribution of ash resembles to that of clays. The chemical analysis reveals that the ash has larger amount of CaCO3 than the clays. The results of XRD supported the presence of quartz (SiO2), calcite (CaCO3), hematite (Fe2O3) and potassium calcium sulphate [K2Ca2(SO4)3] in the ash sample. Here a basic type of natural clay was also characterized as a reference material. The green molded bricks which were made from the mixture of clay and ash, were air-dried at room temperature for 24 h, and then oven dried at 100oC for another 24 h to remove the water content. The raw bricks are then fired in the Blue-M metallurgical muffle furnace to a designated temperature (800, 900 and 1100oC). Then the bricks were characterized both physically and mechanically. The firing behavior (mechanical strength, water absorption, and shrinkage) was determined. The microstructure, phase composition and leaching were evaluated for bricks manufactured at different firing temperature. These results demonstrate that IMSW ash can be recycled in clay bricks. The concentrations of hazardous components in the leachates are below the standard threshold for inert waste category landfill; however, their environmental risk during their use-life step can be considered negligible.