The divergency of microbiological influenced corrosion for diverse pipe materials in the drinking water distribution system

Abstract

Microbiological influenced corrosion (MIC) was prevalent in the water supply industry, especially in drinking water distribution systems (DWDS) where ferrous materials are the main component. The MIC behaviors for four popular pipe materials (304 stainless steel, 316 stainless steel, Q235 carbon steel, and nodular cast iron) were studied by the dynamic water supply network simulation in the paper. The biomass densities of surface coupons in the experimental period were ranked as follows: nodular cast iron (20,562 cells/mm2, ICC) > Q235 carbon steel (8697 cells/mm2, ICC) > 316 stainless steel (6350 cells/mm2, ICC) > 304 stainless steel (5520 cells/mm2, ICC). Microbial community structure was mainly influenced by environmental factors, especially in the pipe materials that significantly impacted dominant genera inhabited on experimental materials, among which the 316 stainless steel showed the best biostability. Moreover, the profile of polarization resistance and corrosion current exhibited a similar variation tendency, which increased in the first 30 days and then decreased later. The maximum corrosion current of each material was 2.10 × 10−4 A (304SS), 2.70 × 10−4 A (316SS), 2.58 × 10−4 A (Q235 carbon steel), and 1.30 × 10−4 A (nodular cast iron). SEM and XRD results confirmed that the surficial porous corrosion layer controlled the diffusion process of iron corrosion where β-FeOOH and γ-FeOOH were the main components of the corrosion product. Overall, the results of community diversity, electrochemical parameters, and corrosion layer structure showed that 316 stainless steel possessed the best biological corrosion resistance among the four kinds of pipes.