Evaluation of microbial agents as corrosion and scale inhibitor for industrial cooling water applications

In this study, six strains of microbial agents were investigated as environmently friendly scale and corrosion inhibitors for industrial cooling water applications. The static jar tests along with characterization methods were applied to evaluate the scale inhibition performance. Results showed that under a concentration of 240 mg/L, the nitrobacteria, denitrobacteria and Lactobacillus agents reached high CaCO₃ scale inhibition efficiencies of 83, 82, and 86% respectively. Characterization methods indicated the deposited crystals morphologies were modified and the crystals peak intensities were lowered. In addition, weight loss measurements, electrochemical measurements, surface characterization analyses were conducted to study the corrosion inhibition performances and mechanisms. It was found that at 40 °C, Bacillus cereus agent with 200 mg/L possessed the highest corrosion inhibition efficiency of 60.11% at 3 d, together with the second-lowest current density of 13.0 μA cm^-2 at 12 d. The corrosion inhibition mechanisms were attributed to biofilm accumulation and biomineralization on Q235 CS surfaces to form protective film. The results suggested microbial agents have promising potential as environmently friendly scale and corrosion inhibitors for industrial cooling water applications.