Mechanistic insights into acidification-augmented coagulation: optimizing cyanobacterial removal and disinfection by-products control

This study develops an acidification-enhanced coagulation (AEC) strategy that selectively modulates algal organic matter (AOM) through pH-controlled interfacial engineering. By implementing mild acid pretreatment (pH 5), the process specifically targets AOM, inducing 54.1 % and 51.7 % reduction of low-polarity proteins and polysaccharides via electrostatic-mediated aggregation, revealed by FT-ICR-MS analysis. The resultant insoluble polymer formation eliminates competitive coagulant-AOM interactions while maintaining cell integrity, contrasting with conventional pre-oxidation that triggers cellular damage. Mechanistic studies reveal the critical role of protonation in modifying AOM's surface charge distribution, thereby enabling effective separation through charge neutralization. At optimal conditions, AEC achieves 60 % coagulant savings and concurrently reduces disinfection by-products (DBPs) formation potential by 30 % (compared with traditional coagulation). The dual mechanism of selective AOM removal and cell integrity maintaining positions this pH-responsive strategy as a sustainable alternative for drinking water treatment plants combating cyanobacterial blooms, particularly in scenarios requiring minimized chemical footprint and enhanced process safety.