Mechanistic insights into alginate-based bioremediation: kinetic and thermodynamic analysis of slaughterhouse wastewater treatment in a continuous packed-bed bioreactor

Abstract Slaughterhouse wastewater (SWW) poses significant environmental challenges due to its high organic load, turbidity, and Total Dissolved Solids (TDS). This study introduces a novel porogen-assisted synthesis approach to fabricate Alginate-Mushroom Bioremediation Beads (AMBB) and Alginate-Algal Bioremediation Beads (AABB), enhancing porosity and mass transfer for efficient SWW treatment in a continuous packed-bed bioreactor. Process factors (flow rates: 1.9–17.9 mL/min; packing heights: 1–5 cm) were optimized, with kinetic, thermodynamic, and mechanistic analyses evaluating pollutant removal mechanisms. AMBB achieved superior removal efficiencies (91.4% turbidity, 85.1% TDS) compared to AABB (87.5% turbidity, 79.9% TDS), driven by synergistic biosorption and fungal enzymatic degradation (Pterocarpus mildbraedii) versus AABB’s biosorption-dominated process (Chroococcidiopsis thermalis). The Pseudo-Second-Order model best described kinetics (R 2 : 0.976–0.987 for AMBB, 0.966–0.981 for AABB), with AMBB’s higher equilibrium capacities (qe: 4.30–4.60 NTU/g for turbidity, 36.0–43.0 mg/g for TDS) reflecting enhanced pollutant uptake. Thermodynamic analysis revealed non-spontaneous (ΔG: 3.25–4.22 kJ/mol), endothermic processes (ΔH: 3.62–4.52 kJ/mol), with AMBB’s lower activation energy (Ea: 7.21–7.99 kJ/mol) indicating reduced energy barriers due to enzymatic activity. Continuous operation outperformed batch systems by 10–20%, attributed to enhanced mass transfer facilitated by the porogen-induced porous structure, as supported by the Intra-Particle Diffusion model. Compared to conventional methods, AMBB and AABB offer sustainable, scalable, low-cost, low-sludge solutions. The innovative porogen-assisted synthesis integrates highly porous matrices with bioactive degradation pathways, providing a robust framework for optimizing biopolymer-based wastewater treatment technologies.