Effective removal of microcystin by a hybrid process combining PAC-submerged hollow fiber membrane from raw water

Abstract

Microcystis aeruginosa is one of the most commonly detected cyanobacteria in aquatic systems. Therefore, this study evaluated the removal efficiency of total (cell-bound and dissolved) microcystin (MC) by a hybrid process combining powdered activated carbon (PAC)-submerged hollow fiber membrane and compared the hybrid process performance with that of PAC adsorption and submerged hollow fiber membrane processes separately. The results indicated that up to 84% of the total MC was removed using the PAC adsorption stand-alone process, while 90% of it was removed by submerged hollow fiber membrane stand-alone process (with a 10 μg/L feed concentration). When the PAC dose of 20 mg/L and equilibrium time of 480 min were applied with a 51.9 μg/L feed concentration to the hybrid process, the removal efficiency of total MC increased to 99%. Moreover, the cell-bound and dissolved MC concentrations in the permeate were 0.34 and 0.65 mg/L, respectively. This permeate concentration level was ensured by the World Health Organization (WHO) as the guideline value for MC (1 mg/L). Overall, the hybrid process combining PAC-submerged hollow fiber membranes can be successfully used as an alternative advanced treatment technology to mitigate total (cell-bound and dissolved) MC. HIGHLIGHTS The membrane stand-alone process was able to ensure the removal of 90% of the total MC.; The hybrid membrane process was capable of considerable removal of total MC (>99%).; The hybrid membrane process significantly enhanced the removal of extracellular MC (47.6%).; The hybrid membrane process achieved a permeate concentration below the WHO guideline value of 1 μg/L.;

Keywords

• adsorption
• hybrid membrane process
• microcystis aeruginosa
• powdered activated carbon
• submerged hollow fiber membrane