Effect of Hazardous Bacteria Isolated From Copper Plumbing System on Microbiologically Influenced Corrosion of Copper

Abstract

Plumbing systems can be affected by Microbiologically Induced Corrosion (MIC). Through this process, microorganisms can modify water quality and jeopardize consumers' health by releasing metal from pipes' surface into the water. While it is known that microorganisms' interactions increase their electrochemical effect on the metal surface, the effect of mixed communities and their interactions remain poorly understood. In this work, we investigated two hazardous bacteria isolated from a copper plumbing system, Variovorax sp, and Ralstonia pickettii. Electrochemical impedance spectroscopy (EIS) showed a changing of oxide layer properties depending on immersion time. At short times, a capacitive behavior was observed at the low-frequency range, transiently including an additional inductive loop. At long times of exposure, the capacitive behavior disappears, and a Warburg behavior is present at the low-frequency. Interestingly, the corrosion was inhibited in pure culture tests, but this effect was reduced when the bacteria formed a consortium. In fact, EIS data show that the highest inhibitor activity was presented by Variovorax sp pure culture, with 3.5-fold reduction in the corrosion rate compared with abiotic condition, and around of 2-fold when copper was exposed to Ralstonia pickettii and the consortium. XPS showed the formation of a different by-product of corrosion in the samples exposed to bacterial action. Moreover, SEM images revealed different bacterial growth behavior at the end of the test period. This research highlights the relevance of understanding the interactions of drinking water microbial communities

Dynamics of Biocorrosion in Copper Pipes under Actual Drinking Water Conditions

“…The development of a heterogeneous biofilm likely enhanced the weak oxide layer with low protective capacity. Previous research revealed that the presence of a consortium of microorganisms with the ability for biofilm production promotes the precipitation of copper hydroxide with low protective function in comparison with the abiotic condition [42]. This situation and regular replacement of water in the copper pipes every 8 h might explain the low coverage of corrosion byproducts on the pipes exposed for 3 and 12 months.…”

“…The presence of sulfate, bicarbonate, and orthophosphate enhances the formation of brochantite and cupric phosphate during long periods, which would prevent the formation of insoluble tenorite or malachite phases [43] from creating a weak oxide layer. Moreover, previous research indicates that the presence of a biofilm creates an acidic microenvironment that hastens the formation of soluble copper compounds as cupric hydroxide (Cu(OH) 2(s) ) [7,25,42,44].…”

Mechanism underlying the acceleration of pitting corrosion of B30 copper–nickel alloy by Pseudomonas aeruginosa

“…Microorganisms, exhibiting a high level of diversity and adaptability, are prevalent in natural and industrial environments. They are capable of causing corrosion in almost all types of metals and alloys ( Galarce et al, 2019 ; Gu et al, 2019 ). The operating environment that condensing systems provide is conducive to the growth and reproduction of microorganisms ( Aruliah and Ting, 2014 ).…”