Optimization of Metal Recovery from MSWI Fly Ash by Acid Leaching: Findings from Laboratory- and Industrial-Scale Experiments

Abstract

A major part of Swiss fly ashes (FA) from municipal solid waste incineration (MSWI) are treated with the acid fly ash leaching process (FLUWA) in order to recover heavy metals prior to deposition. The FLUWA process uses scrub water from wet flue gas cleaning to leach heavy metals from FA. The leaching efficiency is strongly dependent on the leaching conditions (e.g., pH, Eh, L/S-ratio). This case study presents the optimization of the FLUWA process at the MSWI plant Linth, Switzerland, through determination of ideal process parameters for optimal metal recovery. By means of laboratory- and industrial-scale experiments, the process was adjusted towards a more efficient leaching of Zn, Pb, Cu, and Cd. This included the use of an oxidizing agent (hydrogen peroxide). Laboratory experiments proved to be a powerful tool for simulating process optimizations at industrial scale. An ideal leaching pH of 3.8 was determined and it was observed that the process stability is significantly influenced by the L/S-ratio applied to the leaching process. In the course of the study, the recovery could be improved to 67% Zn, 66% Pb, 30% Cu, and 91% Cd. It can be concluded that for optimal metal recovery the process has to be individually adjusted to the composition of the processed FA and scrub water of each specific FLUWA process.

Radioactivity of residues from waste incineration facilities in Finland

“…Previously there have been only a few studies of the radioactivity of waste incineration residues internationally [5][6][7][8], and no studies in Finland. Due to the levels of heavy metals in the residues [9,10] the beneficial use of waste incineration residues can be limited, but as advanced forms of reuse and recycling are developed, such as more efficient metals recovery [11], it is also important to investigate and document the levels of radionuclides in the residues. For this purpose, in this study the residues from nine waste incineration plants in Finland were characterised for natural and artificial radionuclides.…”

Research and Innovation Needs for the Waste-To-Energy Sector towards a Net-Zero Circular Economy

“…Currently, several techniques, mainly of a thermal or hydrometallurgical nature [51], are under study. The greatest economic potential likely lies in the integration with other operations conducted at the WtE plant: for instance, zinc recovery via acid leaching by reusing effluents from wet flue gas cleaning systems, of which the feasibility at an industrial scale was demonstrated recently [52,53].…”

Municipal Solid Waste Fly Ash-Derived Zeolites as Adsorbents for the Recovery of Nutrients and Heavy Metals—A Review

“…Therefore, nearly all MSW incineration FA (MSW-FA) is stabilized/solidified and deposited as toxic waste in landfills, and due to their enormous volumes, taking up valuable space. However, a shift in focus from environmental impacts to resource recovery has identified the potential value of embedded salts and metals in the MSW-FA, and some progress has been made in recovering these resources [5][6][7].…”