Minimization of halogenated disinfection by-product precursors by Al-based electrocoagulation–flotation (ECF) toward cyanobacteria-laden water

Abstract

The presence of toxic algae, such as Microcystis aeruginosa (MA), in drinking water treatment plants (DWTPs) would contribute to algal organic matter (AOM) as precursors toward disinfection by-products (DBPs). Electrocoagulation–flotation (ECF) has shown promising performance in minimizing algal cells from water and dissolved AOM. This study aimed to investigate the effect of current density (CD) and pH on alumina (Al)-based ECF for removing MA cell and DBPs precursors from cyanobacteria-laden water. The performance of Al-based ECF was evaluated at various CD and pH conditions within 20 min. In addition, the total halogenated DBPs formation of the treated suspension after ECF was quantified. At pH 8, the ECF process with 5 mA/cm2 exhibits the most significant reductions in MA cell and soluble AOM, accounting for 97 and 56%, respectively. Additionally, the precursors of trihalomethanes (THMs) and haloketones (HKs) can be effectively removed with flotation despite their significant release at EC. The tremendous reduction of humic acid-like (HAL) substances in extracellular organic matter (EOM) fraction by ECF leads to the minimized THMs formation potential. In summary, Al-based ECF at pH 8 is effective to remove cyanobacteria and minimize the precursors of regulated THMs along with an insignificant reduction in regulated haloacetic acids (HAAs) precursors.