Review of Microbially Induced Corrosion and Comments on Needs Related to Testing Procedures

Abstract

Concrete is the most widely used material for the construction of the wastewater collection, storage, and treatment infrastructure. The chemical and physical characteristics of hydrated Portland cement may make it susceptible to degradation under highly acidic conditions. As a result, some concrete wastewater infrastructure may be susceptible to a multistage degradation process known as microbially induced corrosion (MIC). MIC begins with the production of aqueous hydrogen sulfide (H 2 S (aq) ) by anaerobic sulfate-reducing bacteria present below the waterline. H 2 S (aq) partitions to the gas phase where it is oxidized to sulfuric acid by the aerobic sulfur-oxidizing bacteria Thiobacillus that resides on concrete surfaces above the waterline. Sulfuric acid then attacks the cement paste portion of the concrete matrix through decalcification of calcium hydroxide and calcium silica hydrate coupled with the formation of expansive corrosion products and loss of coarse aggregate. The attack proceeds inward, resulting in reduced service life and potential failure of the concrete structure. There are several challenges associated with assessing a concrete's susceptibility to MIC. First, no standard laboratory tests exist to assess concrete resistance to MIC. Straightforward reproduction of MIC in the laboratory is complicated by the use of microorganisms and hydrogen sulfide gas. Physicochemical tests simulating MIC by immersing concrete specimens in sulfuric acid offer a convenient alternative but do not accurately capture the damage mechanisms associated with biological corrosion. Comparison of results between research studies is difficult due to discrepancies that can arise in mixture design, specimen preparation, and experimental methods even if current ASTM standards are followed.

Effect of Temperature and Acidity of Sulfuric Acid on Concrete Properties

“…This result, together with a visual inspection of the samples, reveals that, during the acid degradation process, the temperature of the sulphuric acid solution accelerates the mass loss by loosening the bonds between aggregates and cement paste. The main focus of large proportion of the available literature within the field has been on the effect of temperature on the bacterial degradation of concrete (Alexander et al 2013and House and Weiss 2014 and to the best of the authors' knowledge there are rather limited investigation results available on temperature effect on chemical acid attack progression in concrete specimens (Okochi et al 2000 andZhang et al 2012). However, in practice concrete can potentially degrade differently in various climate and temperature conditions regardless of presence of bacteria.…”

Evaluating the efficacy of antimicrobial additives against biogenic acidification in simulated wastewater exposure solutions

“…The service life of concrete wastewater infrastructure such as sewer pipelines, manholes, wastewater digesters and septic tanks could be reduced significantly by microbially induced corrosion of concrete (MICC). MICC is a progressive deterioration process that is primarily associated with sulfur oxidizing bacteria (SOB) [1][2][3]. The process begins with the production of hydrogen sulfide (H 2 S) under anaerobic conditions by reduction of sulfate ions (SO 4 -2 ) present in the wastewater by anaerobic sulfate reducing bacteria (SRB) residing below the waterline [4].…”

“…The deterioration of concrete due to MICC has been described using a three-stage progressive deterioration process [1,3,13]. Initially the pH of the surface of the concrete is in the range of 12.5 to 14 [11].…”

Antimicrobial Efficiency of Metallurgical Slags Suitable for Construction Applications

“…Biocorrosion of construction materials is a significant problem wherever the conditions suitable for microorganisms occur. Biocorrosion is caused by varied biogenic acids, as well as by H 2 S and NH 3 , which result from metabolic activities of microorganisms [1][2][3][4]. These corrosive metabolites react with calcareous components of construction materials, finally leading to the biodeterioration.…”