High turbidity water treatment by ceramic microfiltration membrane: Fouling identification and process optimization

Ceramic membranes have been introduced in various fields; however, research on ceramic membranes in high-turbidity environments has been rarely performed. In this study, the fouling characteristics of a ceramic microfiltration membrane in a high-turbidity environment were examined. First, the factors affecting the ceramic-membrane fouling were investigated through filtration tests in various feed-water conditions. Next, as a pretreatment to the membrane process, three types of coagulant were compared, and the optimum coagulant and coagulation concentration were selected. Finally, the ceramic and polymeric membranes' treating of high-turbidity water was compared, with and without coagulation. The results indicated that the turbidity was the major influential factor of irreversible fouling on the ceramic membrane. When the turbidity increased, irreversible fouling occurred rapidly, which may be caused by small particulates entering the membrane, and resulting in standard pore blocking. Therefore, the coagulation experiment was conducted using feed water with high turbidity, which causes the most irreversible fouling. As a result, poly-aluminum chloride was selected as the optimum coagulant. In the comparison between the ceramic and polymer membranes, there was no significant difference in removal efficiency; however, the ceramic membrane had a better water flux and lower membrane-fouling potential. Moreover, the efficiency increased when a coagulation process was used as the pretreatment. Thus, ceramic membranes are more efficient for treating high turbidity water. (C) 2019 Elsevier B.V. All rights reserved.