Impacts of mixed ferrous sulfate-biochar additives on humification and bacterial community during electric field-assisted aerobic composting

Abstract

This study assessed the impact of nine mixed ferrous sulfates and biochars on electric field-assisted aerobic composting (EAC), focusing on the spectroscopy of dissolved organic matter (DOM) and microbial communities. Adding 1.05 % ferrous sulfate and 5.25 % biochar to EAC increased the specific ultraviolet absorbances at 254 and 280 nm by 142.3 % and 133.9 % on day 35, respectively. This ratio accelerated the early response of carboxyl groups (–COOH) and lignin (C = C), enhancing the relative abundance of Thermobifida (4.0 %) and Thermopolyspora (4.3 %). The condition contributed to humus precursor formation on day 5, increasing the maximum fluorescence intensity of the humus-like component by 74.2 % compared to the control on day 35. This study is the first to develop a combined and efficient organic and inorganic additive by multiple-variable experimentation for DOM humification. Consequently, it optimizes EAC for solid waste recycling.