Influence of consortium culture and mixed culture on carbon steel corrosion in B30 storage system

B30, which consisted of 30 %-v biodiesel and 70 %-v petrodiesel, is a renewable fuel that is being developed in Indonesia. In the B30 storage system, microbes utilize B30 and cause corrosion of carbon steel. This research aims to compare the interaction effect of consortium culture (S. marcescens - B. megaterium and S. marcescens - B. licheniformis) and mixed culture on the corrosion of carbon steel in the B30 storage system. The experiment was carried out by immersing carbon steel ST-37 specimens in B30 test medium for 21 days. Sample testing and analysis includes the number of microbial colonies, chemical bonds of biofilm composition, morphology of biofilms and metal surfaces, corrosion rate and corrosion products. The results shows that antagonistic interactions occurred in the consortium culture, resulting in the decrease of corrosion rate. Meanwhile, synergistic interaction occurred between the microbes in the mixed culture, resulting in higher corrosion rate. The corrosion mechanism that occurs in consortium culture and mixed culture involves the same electrochemical reactions.