Membrane processes used to treat scrubber gas desulfuration washwater.

Abstract

Since 2020, hybrid exhaust gas cleaning systems have been installed on container ships to be in line with the International Maritime Organisation regulations. This technology allows the removal of gaseous sulphur oxide compound before atmospheric rejection of exhaust gas with a concentration lower than 0.1% sulphur equivalent. To be also compliant with water discharge criteria, membrane processes used as a water treatment system have been complementary installed onboard maritime vessels. Objectives of our research are to demonstrate the membrane efficiency and performances for this field of application and their reliability for reaching future regulations. Half industrial scale experiments are first carried out in controlled areas. Results allow optimum parameter definition for a sustainable long-term operation as a permeate flux of 60 L h-1 m-2 and a backwash frequency of 40 min. Experiments are scaled up to onboarded units, and previous settings have been validated. The fleet autonomy for a longer period of closed-loop operation is highlighted. Consequently, the fleet is well prepared and able to overcome new regulation for the future sulphur emission area defined for the Mediterranean Sea in 2025. In addition, the usage of membrane processes allows the reduction of pollutants as suspended solid and heavy metal rejection inside the natural environment with a respective retention higher than 100 and 95%.