Experimental Study on Microbial Activity of Ship Ballast Water and Corrosion of Ballast Tank by Inert Flue Gas Deoxidation

To explore how to reduce the corrosion of ship ballast tanks while killing planktonic microorganisms in ship ballast water and meeting the prescribed ballast water discharge standards, an experimental system for inert flue gas pressure-loaded water treatment was established in this paper. The simulated seawater was treated with the combined inert flue gas of N2 and CO2, and the corrosion weight loss of the ballast tank steel plate samples in different corrosive media was simulated. The results showed that when the dissolved oxygen concentration in the ballast water was 0.5 mg/L and the pH value was 6, the mortality of Chlorella reached 100%, the mortality of Escherichia coli was 99.98%, and the microbial lethality met the D-2 standard. The average corrosion rate of the samples in the corrosive medium with an oxygen concentration of 0.5 mg/L and a pH of 6 was 69.02% lower than the average corrosion rate of the samples in simulated seawater. The results were consistent with the results calculated by the weight loss method, which indicated that the use of the inert flue gas deoxygenation method to treat the ship's ballast water reduced the corrosion rate of the ballast tanks.