Evaluation of Sulfate-Reducing Bacteria Biofilms in the Presence of Biocides

Abstract The aim of this study was to evaluate the progression of sulfate-reducing bacteria (SRB) biofilms in the presence of biocides simultaneously with bacterial growth and some electrochemical parameters. Hence, a laboratory system was designed to observe directly the progression of sulfate-reducing biofilms in a flow cell, with the action of two biocides: a commercial product (CB), based on tetrakis-hydroximethyl phosphonium sulfate (THPS), and another formulated from the leaves of the Neem tree (Azadirachta indica), which has been claimed to have antimicrobial properties. At the same time, open circuit potential (OCP) and linear polarization resistance (LPR) of carbon steel electrodes were measured. Potentiodynamic polarization (Tafel) and mass loss techniques were determined at the end of the tests, as well as sessile growth. This paper shows the correlation of each parameter evaluated for each biocide. The results confirm that the natural product based on A. indica presented a similar behavior to that of CB. This demonstrates a potential for using this plant as an environmentally friendly biocide. Further research is required to assess its possible application at an industrial level.