XI Международная студенческая научная конференция Студенческий научный форум - 2019

Electrodialysis can be applied to the continuous-flow type of operation needed in industry. Multi-membrane stacks can be built by alternately spacing anionic- and cationic-selective membranes. Among the technical problems associated with the electrodialysis process, concentration polarization is perhaps the most serious (. Other problems in practical applications include membrane scaling by inorganics in feed solutions as well as membrane fouling by organics [1-2].

The principle behind electrodialysis is that electrical potential gradients will make charged molecules diffuse in a given medium at rates far greater than attainable by chemical potentials between two liquids as in conventional dialysis. When a DC electric current is transmitted through a saline solution, the cations migrate toward the negative terminal, or cathode, and the anions toward the positive terminal, the anode. By adjusting the potential between the terminals or plates, the electric current and, therefore, the flow of ions transported between the plates can be varied[2-5].

The membrane itself is a polymeric coating or extrusion with inverted conical­shaped pores. Membrane filters do not plug because the pore diameter is smaller at the top, which is the point of contact with the wastewater. Material passing through the membrane passes unimpeded through the membrane structure, therefore eliminating accumulation of material within the filter. Wastewater is pumped across the membrane surface at high flow rates. This parallel fluid flow eliminates the cake-like build-up typical of conventional filters such as bags and cartridges which must be frequently replaced. Some wastewater contaminants slowly accumulate on the membrane surface, forming a thin film, during normal operating conditions. This fouling process is normal and causes the filtration rate to slowly decrease with time. When membranes no longer produce clean water at the desired rate they are cleaned in place with soap and water and returned to service. Membranes can be repeatedly cleaned for years of productive, dependable service prior to replacement

Figure 1. Electrodialysis cell diagram,

References

1. Climate Change 2001. Synthesis report. ,Cambrige University Press, UK, 2003.

2. G. I. Marchuk, Mathematical Modelling in Environmental Problems ,Nauka, Moscow ,1982.

3. G. I. Marchuk, Adjoint Equations and Analysis of Complex Systems Kluwer Academic Publishers, Dordrecht, 1995.