A quantitative IC50-based framework integrating multidimensional toxicity of coal-wastewater inhibitors in biological wastewater treatment systems

Coal-derived wastewater contains complex mixtures of persistent organic and inorganic pollutants that impair biological treatment. While many individual inhibitors have been studied, their combined toxicity and process-specific impacts remain poorly understood. This review develops an integrative assessment framework that links IC 50 -based toxicity thresholds to microbial susceptibility and biological process performance. Key inhibitors including cyanides, phenols, thiocyanates, ammonia, PAHs, heavy metals, and nitrogen-containing heterocycles are evaluated across four major biological treatment systems: aerobic oxidation, anaerobic digestion, partial nitritation, and anammox. Special emphasis is placed on synergistic toxicities (e.g., phenol–ammonia interactions) and on the acute sensitivity of nitrifying and anammox bacteria to heterocyclic compounds such as quinoline and pyridine. By aligning inhibitor profiles with mitigation strategies and removal pathways, this review provides a process-informed roadmap for designing resilient, adaptive treatment trains for coal-derived industrial effluents. • An IC50-based framework links coal-wastewater toxicity to bioprocess inhibition • Distinct sensitivities are identified for aerobic, AD, PN, and anammox systems • Toxicity thresholds compared with global discharge standards to reveal gaps • Phenol–ammonia mixtures show synergistic toxicity in PN–anammox systems. • Mitigation is process-specific: Fe-salts, adsorption, and TAN–pH control