Application of Electrodialysis in Waste Water Treatment and Impact of Fouling on Process Performance

摘要

Electrodialysis (ED) is a new advanced separation process that is commonly utilized for producing drinking water from water bodies as well as for the treatment of industrial effluents. ED process is applied on commercial scale. Basically, an ED process consists of an ion exchange membrane and the diving force necessary for applicability of the process is electric potential. Due to the presence of electric potential ions from one solution after passing through ion selective membrane barrier are transferred to another solution. The main factors on which ED process performance depends on concentration of ion in raw water, flow rate, concentration of feed, current density, membrane properties and cell compartments geometry. Fouling which is produced by foulants including organics, colloids and biomass on the inside membrane internal structure or on the outside surface results in reduction of process separation efficiency and energy consumption is enhanced. Fouling increases the membrane resistance and selectivity of membrane is reduced by fouling. Therefore, some methods are proposed to reduce fouling in ED system such as pre-treatment of feed solution, zeta potential control, membrane properties modification and flowrate optimization. It is a need of an hour to suggest a reducing method less energy and thus minimum operating and investment cost. Electrodialysis Reversal (EDR) system can be as regarded as best option because no extra chemicals are required and life of membrane increased by it. In EDR fouling progress is broken by revering electric potential (applied electric field). This paper elaborates ED process briefly and presents an overview of literature review on different kinds of fouling mechanisms. Also, different cleaning methods have been briefly described for enhancing efficiency of ED process.