Electrolysis is well known process for easily generating free chlorine on-site in water containing chloride. Ballast water for stability of ships commonly use sea water or brackish water containing various ions including chloride. The electrolysis is most popular technology among the approved ballast water technologies. This study was aimed to investigate the effective condition for saving energy in artificial seawater electrolysis during formation of total residual oxidant (TRO) to inactivate marine species. The IrO2/Ti electrode was used in salinity range from 4 to 46 PSU. In each salinity, current was given in range from 0.05 to 2 A, then voltage could be monitored in power supply. Electric power in various salinity increased exponentially as function of current, in which low salinity with high resistance increased more rapidly than high salinity with low resistance by 'P=I2R'. The energy for TRO was calculated using the electric power and sampling time of TRO. Figure shows the required energy for generating of 10 mg/L TRO according to the specific current and salinity.  In high salinity, the energy for TRO was similar on various current. However, in low salinity, the current affected the energy. In high current, the low salinity with high resistance required much higher electric power. The low salinity and low current required more time to generate TRO. Consequently, the current range for saving energy was from 0.3 to 0.5 A.

Evaluation of energy efficiency for TRO production in brackish/seawater electrolysis: Effect of salinity and current

248th National Meeting (2014)

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