Chapter seven - Electrochemical membrane technology for fouling control

Abstract

Electrochemical membrane technology, which incorporates electrical and electrochemical reactions into membrane filtration, opens up a new horizon in membranes and membrane processes. Novel electroconductive materials and more efficient process designs are of great interest to make this technology viable in the real field. Regular membranes are utilized for a two-stage serial process setup as long as they are resistant to the residual electrogenerated oxidants. In a single-stage process, ceramic and chemically stable polymeric membranes can be employed. Electroconductive membranes, which act as an electrode and a filter medium, make incremental progress toward the goal of the fabrication of fouling-free and multifunctional filters. Electrochemical membrane filtration mitigates membrane fouling via several phenomena, such as electrophoresis, electrocoagulation, electroflotation, and electrooxidation. Electrophoresis forces the charged particles to move away from the membrane surface having the same charge, reducing membrane fouling caused by particulate deposition. Electrocoagulation generates in situ coagulants (metal ions) aggregating fine particles, reducing pore plugging, and forming loose cake structures at the membrane. Electroflotation generates gas bubbles (H2 and O2) to make the particulate matter buoyant being removed from the aqueous phase. Electrooxidation degrades organic matter and inactivates microorganisms via direct and indirect oxidation reactions, minimizing organic fouling and biofouling. Some challenges remain to be resolved in future research, such as material durability, process intensification with physicochemical or biological treatments, and economic practicality.