Ecotoxicological Monitoring of DSS Microorganisms and Quorum Sensing-Mediated Behavior Control over Metal Corrosion of Al, Zn and Fe

To evaluate the behavior of industrial equipment from a corrosion point of view, it is mandatory to consider both the material that equipment is made from and the working conditions such as temperature, pH, and the existing microorganisms in the working environment. Our studies regarding ecotoxicological monitoring of biological suspensions Diatomee, Saccharomyces, and Spirulina (DSS) are focused on three directions: (1) the evolution of chemical and biological parameters of the reaction environment (pH, conductivity, TDS, DO, OD), the kinetics of DSS microorganisms’ growing curve; (2) the analysis of biofilm forming on the exposed metallic surface and (3) the analysis of corrosion degree (phenomena) of tested metals in five media, by using the corrosion indices: volumetric index, gravimetric index, and penetration index. The viability of microorganisms in the presence of aluminum, zinc, and iron shows the following sequence: Al Diat > Fe Diat > Zn Diat > Al Spir > Zn Spir> Al Sach > Zn Sach > Fe Spir > Fe Sach. The development of biofilms on the surface of metal plates followed the sequence outlined below: Al Diat > Fe Diat > Zn Diat > Fe Spir > Zn Sach > Fe Sach > Al Sach > Zn Spir > Al Spir. Iron exhibits the most favorable performance, displaying a very low Ip value across all tested environments, including salt water. Aluminum demonstrates sensitivity to specific biological environments, with the highest degree of corrosion observed in Spirulina, indicating that not all biological environments confer protection to aluminum. Diatoms and Saccharomyces suspensions exert an inhibitory effect on corrosion. Zinc is the most susceptible metal, experiencing the greatest corrosion in Spirulina, followed by salt water, while biological environments only partially mitigate the corrosion rate.