Simultaneous control of algal micropollutants based on ball-milled powdered activated carbon in combination with permanganate oxidation and coagulation.

ABSTRACT

This study reports application of KMnO4 pre-oxidation and engineered powdered activated carbon (PAC) adsorption to simultaneously control geosmin, 2-methylisoborneol (2-MIB), and microcystin-LR (MC-LR) in conventional drinking water treatment plants (DWTPs). Pulverization of commercial wood-based PAC (1 mm ZrO2 ball, 12 h) reduced the median size to ~6 µm and resulted in overall enhanced kinetics for adsorption of the algal micropollutants. A series of parametric experiments were performed to estimate minimal contact for KMnO4 (1 mg L-1, 10 minutes) and PAC (20 mg L-1, 40 minutes) prior to coagulation, with the aim to meet guidelines (0.02, 0.02, and 1 µg L-1 for geosmin, 2-MIB, and MC-LR, respectively) at specific influent concentrations (0.1, 0.1, and 100 µg L-1) in surface water matrix. Ball-milling of parent PAC with a low oxygen content (~2.5 w/w%) could avoid interferences from/to the KMnO4 pre-oxidation and subsequent coagulation. Pilot-scale experiments confirmed the compatibility of the combined KMnO4 and PAC at existing DWTPs.