Quaternary ammonium compounds (QACs) are widely used in consumer products and industrial processes as disinfectants. In water resource recovery facilities, a substantial portion of QACs reside with solids, and thus pass through anaerobic digesters. As antimicrobial agents, QACs present a potential risk to digester operation, yet we have limited understanding of their toxicity to this unit operation. This research combined experimental analysis with advanced machine learning to evaluate acute QAC