Assessment of dissolved organics and disinfection byproduct (DBP) levels through an advanced wastewater treatment strategy consisting of enhanced coagulation, ozonation, and ultrafiltration

ABSTRACT Disinfection byproducts (DBPs) resulting from reactions between dissolved organic matter (DOM) and disinfectants following wastewater treatment pose risks to humans and aquatic environments. While enhanced coagulation and ozonation are widely used to reduce DOM and DBP formation, performance of ultrafiltration (UF) following these treatments is less understood, despite its potential to improve overall effluent quality and ensure safe water reuse. This study investigated DOM removal during enhanced coagulation and ozonation pretreatment, and its impact on DBP formation and associated toxicities during pretreated-UF processes. The results showed 41 and 34% reduction in haloacetonitrile formation potential (HANFP) and haloacetamide formation potential (HAMFP) with 120 mg/L polyaluminum chloride (PACl), respectively, and 48 and 41% reduction with 120 mg/L ferric chloride (FC). Trihalomethane formation potential (THMFP) reduced by 36 and 53% with 120 mg/L of PACl and FC, respectively. Ozonation increased brominated DBP concentrations and combining enhanced coagulation with ozonation achieved similar DBP reductions as enhanced coagulation alone. Ultrafiltration altered the DOM optical properties, as reflected by SUVA254 changes, but contributed minimally to overall DOM and DBP precursor removal. Excitation–emission matrix (EEM) spectroscopy revealed that ozonation generates soluble microbial product (SMP)-like organics and proteinaceous compounds that are ineffectively removed during subsequent UF treatment.