The effect of biological methods for MSW treatment on the physicochemical, microbiological and phytotoxic properties of used biofilter bed media.

• Used biofilter bed media after biological treatment of MSW are characterized. • Properties of used biofilter media depend on type of biological treatment method. • Bed media from biodrying pose little threat to the environment. • Bed media from aerobic biostabilization exhibit high phytotoxicity. • Aerobic biostabilization has impact on microbiological contamination of bed media. Biofilters are commonly used in municipal solid waste treatment (MSW) facilities to remove odors and pollutants from process gases. However, the effectiveness of biofilter bed media decreases over time, necessitating periodic replacement. The type of the treatment process may affect the lifespan of the bed and the way it should be utilized after replacement. This study aimed to analyze the physical, chemical, calorific, microbiological, and phytotoxic parameters of bed media in biofilters operated at an industrial scale in MSW treatment plants. The experiments included three full cycles of biofiltering gases from biodrying, composting, and aerobic biostabilization in two variations. Physicochemical properties (moisture, organic matter, carbon, nitrogen, sulfur, heavy metal contents), respiration activity (AT4), phytotoxicity, and microorganism abundance were determined for initial materials and samples from two biofilter layers collected after each cycle. Results revealed a substantial reduction in AT4 (by 63%-87% compared to initial material), significant moisture content increase in the bottom layers (by 61% or more, depending on the process), and a considerable decrease in microorganism abundance. Biofilter bed media from biodrying and composting exhibited low environmental risk (low heavy metal concentrations, negligible phytotoxicity, and microbiological stability). However, bed packings from aerobic biostabilization processes showed significant inhibition of indicator plants and incomplete sanitization (presence of pathogens like E. coli and Salmonella spp.). Therefore, these bed packings can be utilized for energy recovery, such as incineration after drying. This research provides significant insights into the effectiveness and safety of biofilter bed media in MSW treatment plants. [ABSTRACT FROM AUTHOR]