Behavior and Biochemical Mechanism of High Iron Attapulgite Dosages Affecting Sewage Sludge Composting

We first revealed the behavior and biochemical mechanism of high iron attapulgite (HIAP) different dosages affecting sewage sludge (SS) composting. HS/TOC ratio increased, but HA/TOC HA/FA ratios reduced with increase in HIAP dose. High-dose promoted formation more HS by weak catalytic effect could bind FA than HA strong adsorption to inhibit polymerization adsorbed into HA. Mixing SS subsequent composting as two consecutive processes during HIAP-amended significantly influenced species distribution heavy metals (HMs) Cu, Zn, Cr. Each process roughly contributed one-half HMs passivation. The bioavailable fraction (BF) dose greatly affected microbial community. Both 1% 5% treatments Proteobacteria Firmicutes, 10% Actinobacteriota Bacteroidota. At thermophilic phase, core genera, which were correlated pile temperature pH value. In maturity stage, genera basically similar closely HA, influence order was BF–Cr > BF–Cu BF–Zn optimal recommended.