Corrosion of metal and other materials by microorganisms is a major problem worldwide. Walsh et al. (1993) estimated overall Microbiologically Influenced Corrosion (MIC) damages at $30-50 billion per year in the United States.
Costerton and Boivin (1991) estimated that the MIC costs in production, transport, and storage of oil could be some hundred million US dollars in the US every year due to Sulfate Reducing Bacteria (SRB) alone, not including the costs for lost oil and
environmental clean-up. MIC also occurs in many other industries such as chemical processing, water treatment and nuclear power generation. As water-wetting is becoming more and more common in oil and gas transportation due to increased use of water-flooding
for enhanced oil recovery, fast MIC failures will become more and more common. It is possible that, once in the water-wetting flow regime, pipelines can fail in as little as one year or less due to MIC alone (i.e., due to Microbiologically
The shale oil and gas boom in the Permian basin is pushing MIC in the forefront of corrosion, where MIC far exceeds the threats from CO2 and H2S because of a lack of
clean water in production. Failures expected in years are now occurring after only months.
Prof. Gu is a trained biochemical engineer (PhD, Purdue University, 1990) who has also learned microbiology/molecular biology, bio-electrochemistry and corrosion engineering. He has co-authored numerous papers on MIC, including 20 papers in Corrosion Science (flagship journal in corrosion)
alone in recent years. A list is available at his home page . He has developed several theories and dispelled several myths that confused MIC people for years. Biochemical engineers optimize the utilization of organic carbon and energy sources to maximize production of bio-products.
They want to know exactly how the resources are utilized. This turns out to be quite useful for MIC mechanism investigations. Prof. Gu is the first MIC investigator to apply bioenergetics systematically to investigate the "motive" of why biofilms attack metals. For Type I MIC
(also known as EET-MIC or extracellular electron transfer MIC) attacks by XRB (sulfate or nitrate/nitrite reducing bacteria, and CO2 reducing methanogens) (see our NACE/2012 Paper C2012-0001214), biofilms intentionally utilize elemental iron directly as a fuel molecule to harvest energy
when there is a local deficiency of organic carbon (NACE/2011 Paper #11276). From this angle, we have achieved a brand-new understanding of basic MIC mechanisms and synergy in biofilm consortia. This has resulted in several discoveries that have immediate practical applications in biofilm
and MIC detections. It has also led to our first mechanistic MIC model based on electrochemical kinetics and mass transfer for the prediction of MIC pit growth. As part of a large corrosion institute with extensive expertise on CO2, H2S and sulfur corrosion, we have benefited greatly from
conventional corrosion engineers by performing corrosion tests correctly, thus avoiding costly mistakes easily found in published MIC literature.
MIC mitigation relies on biocide and scrubbing (pigging). It is hard to
develop biocide resistance to a specific broad-spectrum biocide such as glutaraldehyde and THPS. However, these biocides exert a selective pressure on an environmental microbial consortium. This allows more resistant
microbial species to take up the niche, leading to a more resistant (changed) consortium. Environmental concerns desire more effective biocide applications. It is unlikely that there will be another blockbuster biocide like THPS or glutaraldehyde on the market any time soon due to various issues
such as operational issues and licensing. It is a rational approach to enhance existing biocides for more effective biofilm treatment. The best way to do it is to "convince" sessile (biofilm) cells to become planktonic cells that are much easier to kill. We have found some chemicals in pet food
and soy that are not biocidal. They are analogs to bacterial wall components. They can modify the wall slightly causing sessile cells to detach and move on as planktonic cells under a suitable biocide stress (e.g., THPS at 50 ppm by mass). One of the chemicals is effective at 1 ppm or below.
The biocide cocktail is very effective in prevention of biofilm establishment and removal of established biofilms in lab tests. We have also done research on a peptide inspired by a sea anemone that has biofilm-free exteriors. This small heat-stable (> 125 oC) peptide enhances THPS greatly at
an unheard of concentration as low as 18 ppb (w/w) in the treatment of a very tough oilfield biofilm consortium. Please contact us if you are interested in research or field trials.
MIC and biofilm detections are critical in decision-making for treatment that can be costly. Currently,
MIC test kits are all microbe test kits that can only detect the presence of microbes. The present of microbes do not automatically mean MIC. Identifying more and more microbes does not
advance MIC research to the next stage as we haven't learned enough about how these microbes attack. Our new understanding of MIC mechanisms has made it possible for us to start investigating new ways to detect biofilms online and to sense the MIC process directly. We know that it is not
enough to have a ?bug list? from metagenomics. As a matter of fact, even a gene abundance list does not cut it because lots of microbes have electron transfer genes and acid producing genes, but they are not necessarily expressed in the current setting. It has been shown by non-MIC
researchers that within the same APB biofilm, the pH difference between two neighboring locations can be 2 or higher. This means biofilm ecology underneath a biofilm can be vastly different from that in the bulk fluid. Unfortunately, many mechanistic studies did not even dig into
biofilm ecology. Our most recent Corrosion Science paper on headspace increase and Fe2+ concentration increase in
SRB corrosion of carbon steel clearly indicate that such simple changes in the growth environment can increase corrosion weight loss and pit depth by 200% to 500%. In these two cases, dissolved [H2S], iron sulfide precipitation trends were completely opposite and yet both changes
led to increased corrosion. The underlining common causal factor was the increase sessile cell count (due to H2S escape to the headspace and detoxification of H2S), which led to more electron harvest from elemental iron by SRB. Unfortunately, the vast majority of
SRB corrosion data out there lacked sessile cell data, which can easily lead to erroneous conclusions based on superficial observations.
Over past one and a half decade, Prof. Gu's MIC group has performed various MIC projects for companies such as BP, ExxonMobil, Saudi Aramco, SABIC, Total, Petronas, PNR, PTTEP, etc. We are currently soliciting sponsors for various MIC projects. Our MIC-JIP (joint industry project)
is continuously recruiting sponsors. If you are interested in our MIC-JIP or doing any one-on-one proprietary projects, please feel free to contact Prof. T. Gu at email@example.com
or call 740-593-1499. We can come to you to present our advanced views of MIC problems and solutions. By joining the MIC-JIP, you have some of the brightest minds in MIC to answer your MIC questions such as proper sampling methods and mitigation strategies, and to help solve your
technical problems. The current membership fee is $50k/year with a renewable 3-year term (early withdrawal allowed). A sponsor may send an admissible employee for graduate degree (MS or PhD) or for training without bench fees. A low-tier membership is also possible.
Members automatically get our MIC prediction software. Members and OU researchers decide what research topics to work on. Some sample topics are listed below.
(A) MIC mechanisms and modeling, (B) MIC detection, and (C) MIC mitigation.
A-1. Investigation of APB attacks (Type II MIC or metabolite MIC/M-MIC) with local pH measurement under a biofilm
A-2. MIC in underdeposit attacks involving sand
A-3. MIC in hydrotesting including high-pressure tests
A-4. Biofilm formation and MIC pitting attack under different flow conditions
A-5. Mechanistic MIC modeling involving EET-MIC and M-MIC attacks and establishment of a database for biofilm aggressiveness for pure strain microbes and field biofilm consortia
A-6. Investigation and mechanistic modeling of synergistic SRB and CO2 corrosion
B-1. Reliable and inexpensive new online biofilm sensors using novel electrochemical technologies
B-2. Disposable MIC test kits with portable base station
C-1. Evaluations of efficacies of new enhanced biocide cocktails and their compatibilities with corrosion inhibitors and other performance chemicals
C-2. Biocide treatment of sewage water for shale operations
C-3. Mitigation of MIC in hydrotest
C-4. Investigation of corrosion and mitigation of MIC pitting on high-grade stainless steel and titanium that are increasingly used in oil and gas.
Please contact Tingyue Gu for more information.