Effect of Sulphate reducing bacterial-biofilm isolated from refinery cooling water system and sonication on corrosion of carbon steel

Biofilm formation is one of the major problems of recirculating cooling water systems which detriments the life of equipment, through biocorrosion or microbiologically influenced corrosion (MIC). Sulfate reducing bacteria (SRB) are considered to be the major bacterial group involved in MIC. In the present study, SRB cultures are isolated from aeration basin inlet water sample of cooling water system of refinery and immersion test is done to analyze the effect of SRB-biofilm on the corrosion of carbon steel. Furthermore, the effect of sonication on total microbial count, SRB count and corrosion rate is evaluated. Experimental results concluded that SRB biofilm enhances the corrosion rate, involving a number of general and localized features on the metal surface, which were interpreted by Scanning electron microscopy (SEM). SEM studies, of metal surface showed amorphous and crystalline types of biofilm. Also, the efficacy of sonication is evidenced by a significant decrease in microbial counts of water sample and the corrosion rate of carbon steel.