Municipal Solid Incineration Fly Ash Research Articles

Thermal co-treatment of aluminum dross and municipal solid waste incineration fly ash: Mineral transformation, crusting prevention, detoxification, and low-carbon cementitious material preparation

Harmless disposal and resource utilization of hazardous industrial wastes has become an important issue with the green development of human society. However, resource utilization of hazardous solid wastes, such as the production of cementitious materials, is usually accompanied by a pretreatment process to remove adverse impurities that contaminate the final product. In this study, aluminum dross (AD) was thermally co-treated with another hazardous waste, municipal solid incineration fly ash (MSWI-FA), to synergistically solidify F and Na, control leaching of heavy metals, and remove chloride impurities. Significant crusting was observed when AD was thermally treated by itself, but not when AD and MSWI-FA were thermally co-treated. In the process of co-thermal treatment, the remaining Cl, Na, and K contents were reduced to as low as 0.3%, 1.8%, and 0.6%, respectively. CaO and SiO2 in MSWI-FA reacted with Na3AlF6 and Al2O3 in AD, and formed CaF2 and Na6(AlSiO4)6, which contributed to the prevention of crusting and limited the leaching concentrations of F and Na to below detection thresholds and 270.6 mg/L, respectively. In addition, heavy metals were well solidified, and dioxins were fully decomposed during thermal treatment. Finally, a sulfoaluminate cementitious material (SACM) with high early- and later-age strengths was successfully created via synergetic complementarity using thermally co-treated AD and MSWI-FA together with other solid wastes. Collectively, this study outlines a promising method for the efficient and sustainable utilization of AD and MSWI-FA.

Controlling Role of CaClOH in the Process of Dechlorination for Municipal Solid Incineration Fly Ash Utilization

The existence of high chlorine components in municipal solid waste incineration fly ash (IFA) has become a key bottleneck in the utilization of IFA as building materials. In this work, the chlorides in IFA were classified as alkali chlorine, calcium chloride, and calcium aluminum chloride, whereas CaClOH was the dominant phase of calcium chloride. For the first time, the effects of CaClOH on chlorine elimination for IFA-derived products by water-washing treatment or high-temperature treatment were carefully examined. The results indicated that IFA chlorine removal was closely linked to CaClOH phase dissolution, decomposition, volatilization, and transformation. CaClOH was easily removed by water washing and had excellent thermostability, even at 1300 °C. As shown in the results of XRD and XRF, the siliceous component would combine with CaClOH to volatilize as SiCl4, whereas the aluminous component would react with CaClOH to form chlorine-fixed and stable calcium aluminum chloride phases. The calcium aluminum chloride instead of CaClOH was in favor of the transformation of residual chlorine from soluble chlorine to chemically fixed chlorine. Therefore, the detoxification mechanism of chlorine for IFA could be summarized as washing dechlorination, volatilization dechlorination, and chemical fixation. As an application, the synergistic treatment of IFA with siliceous/aluminous materials could greatly reduce risks from soluble chlorine, while IFA-derived products were used as building materials.

The Research of Heavy Metals Stabilization in the Municipal Solid Waste Incineration Fly Ash Using Silica Nanocomposites

Abstract Municipal solid waste has become a serious problem because of rapid urbanization and great economic growth. As a result of these, huge impacts on the environment lead to a lot of problems not only air, soil or water pollution but human health too. One of the solutions to manage MSW problem is incineration with energy recovery that can reduce a large amount of waste in volume. But the activity of incineration plant is associated with the formation of a large amount of hazardous waste, a significant part is fly ash which is by-products of MSW contains a high number of heavy metals and salts which are very toxic. Fly ash is a really topical question today and it is important to find out how to dispose of it properly due to hazardous contents. In this study was performed the municipal solid incineration fly ash evaluation, experimental research of heavy metal composition of seven types of a concrete mixture containing different amounts of MSWI fly ash, silica nanocomposites for the determination of the best alternative and employing a SWOT analysis.

Improved Reactivity of Volcanic Ash using Municipal Solid Incinerator Fly Ash for Alkali-Activated Cement Synthesis

In this work, municipal solid waste incinerator fly ash (MSWI-FA) was used as precursor to alter the reactivity of low reactive volcanic ash (VA) for alkali-activated cement synthesised. The effects of various proportions of MSWI-FA (0, 5, 10, 15 and 20%) on the final properties of the inorganic polymer are reported. The increase in MSWI-FA content increases the heat of reaction in MSWI-FA as the result of the reaction between the amorphous alumina-silica and the Ca-rich precursor. Isothermal conduction calorimetry, FTIR, XRD SEM/EDS, and physico-mechanical analyses were used to follow up the different formulations. New crystalline phases, namely Margarite (CaAl2 (Al2Si2)O10(OH)2, PDF#04-013-3004), Mordernite-(Ca) ((Ca, Na2, K2)(Al2 Si10 O24)·7H2O, PDF#00-011-0155) and Thernadite (Na2SO4, PDF#01-074-2036) confirm the good reactivity. The SEM/EDS exhibited the coexistence of C–S(-N-A)–H and N-A-S-H gels in binary system alkali-activated. The compressive strength and bulk density ranged from 9.38 to 21.07 MPa and from 1.56 to 1.77 g/cm3, respectively. These results indicated the possibility to use VA and MSWI-FA to synthesize room temperature alkali-activated matrices applicable in the manufacture of structural and functional materials. MSWI-FA appears energy-efficient and sustainable solution for the improvement of the volcanic ash based alkaline activated materials.