The effect of sufate-reducing bacteria and iron bacteria on corrosion in water distribution systems

Sulfate reducing bacteria (SRB) and iron bacteria (IRB) are the main microorganisms that can affect the iron corrosion process in water pipelines. Microbiologically influenced corrosion (MIC) is always coupled with electrochemical process. Through the study on the growth of bacteria combined with electrochemical methods, it is possible to understand how microorganisms affect the corrosion process. Coupon test was conducted to acquire the corrosion rate with corresponding growth curve. Ecorr of SRB and IRB differed from each other and the growth curve varied when they coexisted. Basically, the growth curve of bacteria inclined towards steady after 3 or 4 days. The growth curve of IRB was of difference from that of mixed bacteria. The quantity of IRB increased more quickly at 30 °C. With the immersion in the bacteria, the corrosion rate increased obviously compared with that exposed to drinking water. SRB had greater impact on the corrosion process than IRB. However, the sample within the mixture of IRB and SRB present a smaller corrosion rate.