Accelerated on-site weathering of MSWI bottom ash

Municipal solid waste incinerator ash (MSWI bottom ash) exerts a strongly alkaline reaction, with the risk of increased emissions of Pb, Al, Zn and Cu after direct landfilling. In the current project, treatment of MSWI bottom ash with CO 2 from landfill gas prior to landfilling is proposed. According to results of previous investigations, this treatment leads to accelerated weathering of MSWI bottom ash and a reduction of the leachability of Pb, Al, Zn and Cu. We assume that landfill gas with low CH 4 content, so-called "lean landfill gas" (CH4 content < 35 Vol.%) could be used for the on-site accelerated weathering of MSWI bottom ash. "On-site" means that the treatment is performed directly at the landfill site, where the remaining CH 4 -enriched gas streams can be utilized in gas motors for the production of electricity or incinerated in gas flares. We propose to demonstrate the feasibility of on-site treatment of MSWI bottom ash by technical-scale weathering experiments in landfill simulation reactors (LSR) and weathering boxes. Moreover, additional aims of the project are: - Identification and quantification of the environmental benefits and burdens generated by the accelerated on-site CO 2 weathering. Four promising on-site treatment scenarios will be developed, and all material and energy fluxes related to greenhouse gas (GHG) emissions of these scenarios will be determined. - Based on this environmental assessment, the description of one or two optimized concepts for on-site CO 2 treatment of MSWI bottom ash will form part of the summary / conclusions of the final report. The sustainability of the optimized concept(s) will be analyzed. - Development of innovative indicators for weathering/ CO 2 stabilization of MSWI bottom ash with the aid of FT- IR and recently developed thermoanalytical methods. By the realization of the optimized concepts, a prolongation of the operation time for gas motors and gas flares is expected. As a consequence, a significant reduction of GHG emissions (CH4 ) from the older parts of the landfill is achieved.