Side Stream Electrodialysis
OceanSaver MKII BWTS is based on the principle of filtration and disinfection by side stream electrodialysis. Containing approximately 1% of the total ballast flow this side stream is feed through our patented C2E electrodialysis cell to produce a concentrated, highly efficient oxidant with short half-life characterized by rapid consumption. The electrodialysis process will have a greater efficiency compared to conventional electrolysis or oxidizing disinfectants as it only requires a very limited dosage.
Ion Exchange Membrane = Increased Efficiency
Water fed to the C2E is used as an electrolyte in the membrane cell where an ion exchange membrane is isolating the electrodes forming «anode chambers» and «cathode chambers» producing «anolyte» and «catholyte» respectively. The anolyte is acidic whilst the catholyte is an alkaline. The anolyte is partially neutralised by mixing with the catholyte to achieve the desired oxidant mix. When this mix is injected into the ballast water, chemical processes will take place creating additional oxidants – killing organisms, bacteria and viruses present in the ballast water rapidly. This mix contains generated disinfectants and mainly Hypochlorous acid and Hypobromeous species.
DNV Approved Safe H2 Gas Handling = Increased Safety
All BWT systems utilizing electrolysis will produce hydrogen gas as a bi product. In a conventional electrolysis cell, hypochlorite and hydrogen is produced in the same chamber, hydrogen is then vented through a gas trap mixed with chlorine gas to form Hydrogen Chloride a corrosive, toxic, explosive and highly flammable gas. A conventional system will have to increase the oxidant production due to the loss of chlorine gas in this venting process. OceanSaver patented electrodialysis cell produces clean hydrogen on the catode side without any mixture with chlorine, it is then vented safely overboard using our DNV class approved safe gas handing system.
Optimized Operational Parameters = Full Control Over Chemical Reactions
Power consumption on all electrolysis salt water processes is highly dependent upon water temperature and salinity in the water as described in the graph. OceanSaver MKII uses a heating unit either a waste water or a steam type heater on 1/3 of the side stream in order to reduce power consumption of the C2E cell. Salinity will at all times be above 20 PSU in order to optimize the electrodialysis process. In a port with low salinity, the system will automatically change over and use feed water with a high salinity stored in the Aft peak tank or any other dedicated tank.
Intelligent Automation = Optimized Power Consumption
During a ballast loading operation the Trace Residual Oxidants (TRO) in the water is measured after the hypoclorite injection to ensure proper treatment. A complex algorithm calculates the TRO decay from the point of injection to the measurement point based on salinity and organism load. This vale is then used to calculate an accurate consumption of TRO in the water and adjusts the power on the C2E cell. As a result the system will ensure No Overdosing or Under-dosing with an Optimized real-life power consumption.
- C2E Nominal Power calculations based on ambient conditions: Active electrolyte (anolyte) @ PSU 20/ 17 deg C
Other flow rates are available on demand