An ED process can increase the salt content of the brine. Though, it still needs to be treated/disposed of after wards (Turek, 2003). This process is subject to high capital and operating costs (Kepke, n.d.).
CAPACITIVE DEIONISATION (CDI)
The CDI process can remove inorganic compounds. The process cycle consist of three phases namely the purification phase, the rejection phase and the purge phase. During the purification phase, the electrical potential (about 1.5 volts) between the two electrodes removes the dissolved ions form the water as its passes through the cell. The permeate conductivity will decrease and therefore generate a water product. Regeneration takes place by reversing the potential across the two electrodes. The ions are expelled from the electrodes into the rinse water that is purged out of the cell. In general, the CDI process has lower energy requirements as compared with other membrane process since high pressure pumps are not needed (Ng, 2008).
