Regulation effect of polymeric and mineral additives on vermicomposting of biochemical tailings of kitchen wastes

To enhance the ecological recycling of biochemical tailings of kitchen wastes (BTKW), this study addresses the challenges of high salinity and low maturity by employing hydrolyzed polymaleic anhydride (HPMA) and bone char (BC) as polymeric and mineral additives, respectively. The research investigates the individual and synergistic effects of these additives on the vermicomposting process of BTKW, analyzing the alterations in physicochemical properties, enzymatic activities, and the structural dynamics of the bacterial community throughout the composting process. The results demonstrated that both individual and combined applications of HPMA and BC significantly enhanced earthworm growth, with the combined treatment exhibiting the most pronounced effects. Compared with the treatment without additives, the co-application of HPMA and BC markedly reduced the pH value, electrical conductivity (EC) and C/N ratio of BTKW ( p < 0.001). Earthworm treatment substantially improved the total nutrient content, seed germination rate (GI), and catalase activity (CAT), while decreasing the organic matter (OM) content, urease activity (UA), and alkaline phosphatase activity (AKP) throughout the vermicomposting process. Furthermore, the combined application of HPMA and BC significantly enhanced bacterial diversity and selectively enriched beneficial microbial populations associated with organic matter degradation and pathogen suppression. These findings collectively suggest that the synergistic application of polymeric and mineral additives represents an effective strategy for optimizing the vermicomposting process of BTKW, potentially offering a sustainable solution for kitchen waste management. • Polymeric (HPMA) and mineral (BC) additives synergistically optimize biochemical tailings from kitchen waste (BTKW) vermicomposting, offering a viable eco-friendly solution for kitchen waste recycling. • HPMA and BC effectively lower pH, electrical conductivity (EC), and C/N ratio (p < 0.001) while increasing nutrient retention and seed germination index (GI), addressing key challenges of high salinity and low maturity in BTKW vermicomposting. • Earthworm treatment increases total nutrient content and GI, while reducing organic matter (OM) content, indicating improved vermicompost quality. • The combined additives boost bacterial diversity and selectively promote beneficial microbes involved in organic degradation and pathogen suppression, enhancing composting efficiency.