09-Nov-16, Clusta information day MIC, Nazareth, The Netherlands

Dr. Nanni Noël +31 6 468 472 96

Microbial corrosion & biofilms nanni.noel@endures.nl

Microbiologically induced corrosion (MIC) How microorganisms attack different

materials

Corrosion and Antifouling research since 1964

Expertise:

Corrosion

Electrochemistry

Metallurgy

Antifouling

Microbiology

Coatings

Material durability in seawater (composites, adhesive joints)

Natural seawater

Outdoor exposure

Endures BV, Den Helder, The Netherlands

SEM/EDXAFM/ SKPFM

Stereo microscope

Fluorescence microscope

Ship tank model

MIC cultures

Sensors

Electrochemical techniques

Staining techniques

Monopile modelin natural seawater

Endures laboratory facilities

High pressure setup

Anaerobic glove box

Microbial influenced corrosion (MIC)

MIC is a rapid form of corrosion initiated or accelerated by microorganisms

Localized form of corrosion Direct or indirect mechanism Up to 20% of all serious corrosion events are related to MIC It affects a wide diversity of industriese.g. water distribution systems, oil and gas, maritime, offshore, food industry…

General facts about microorganisms:

Characteristics of microorganisms related to MIC: (Borenstein, 1994)

Microorganisms (MO’s) interact with surfaces and form a biofilm:

1. (a) = cells attach to the surface biofilm formation

2. (b) = aerobic and anaerobic zones are formed MO’s create their own environment

3. (c) = ions are trapped, chemical and physical gradients are created localized at the metal surface dissolving of the metal and pit formation

Biofilms, critical factor for MIC

Preferred sites for attachment are (micro-) scratches, cracks, crevices etc.

MIC and diversity of microorganisms

Uptake of nutrients out of liquid or soil, conversion to

acids and other corrosive by-products such as CH4,H2S

etc.

Change of local environmental conditions

acceleration of corrosion processes

resulting in pitting, cracking and other forms of

damagesDamage of materials such as metals, concrete or polymers is

possible!

- low oxygen concentrations under biofilm

- formation of electrochemical cell

region under the biofilm= anode (corrodes), region without biofilm = cathode

(Borenstein, 1994)

biofilm-formed oxygen concentration cell

aerobe

anaerobe

Concentration elements caused by biofilms:

Fungi

Methanogens

Organic Acid Producing Bacteria

Slime Forming Bacteria

Sulphate Reducing Bacteria (SRB)

Acid Producing Bacteria (APB)

Metal-Depositing Bacteria (MDB)

Metal-Reducing Bacteria (MRB)

Sulfur Oxidising Bacteria (SOB)

Iron/Manganese Oxidising Bacteria (IOB)

MIC diversity

Prerequisite for life

1. Water

2. Energy source (Light or chemicals)

3. Carbon source (CO2,C org)

4. Electron donor (anorg, org)

5. Electron acceptor - Oxygen aerob- SO4

2- , CO2 , H2

Example: Sulfur-related microorganisms

Environmental example:

Diversity of MIC

Presence of MIC:

• Fresh, brackish, or sea water

• Stagnant or flowing water

• Different materials are attacked: metals, polymers, concrete etc.

• Coatings: cracks, scratches, pits etc are favoured for bacterial attachment

• Weld: preffered spots for microbial attachment

- Surface roughness- Change of surface chemistry and microstructure (availability of nutrients from the bulk)- Generation of heterogeneous surface

D.N. French D.N. French

304 & 316 stainless steelpipes, chlorinated drinking water

Environmental examples: buried metallic pipelines

Corrosion systems in a buried pipe:

- External corrosion problems= with regard to the soil, the coating or cathodic protection system

- Internal corrosion= with regard to the fluid, lining

- Corrosion due to wrong material, wrong/ incomplete hydrotesting...

Lock infrastructure:

• Fresh water, can be stagnant

• High load of organic material

• Several centimeter thick tubercles were found

Lock infrastructures

microorganisms were detected

Lock infrastructures

Severe microbiological deterioration of concrete in a tank of a wastewater treatment plant. Due to

the damage the rebar has become exposed. Microbial corrosion was the reason due to the

activity of sulfur oxidizing bacteria.

MIC and concrete in wastewater systems

•Alkaline properties of concrete due to acidification decreased

• The protected environment of the reinforcing disappeared.

• In such acidic conditions, MIC is able to develop

Harbor piles

Situation: uncoated mooring posts in harbor beneath Low Water Level

and in soil, coated above Low Water Level

• Perforations after 5 years just beneath LW-level

• Corroded locations are characterized by:

-Very severe local attack from outside

-Pits bowl shaped, covered by red-orange colored corrosion products

-Underneath blank shiny steel

-On these spots no fouling

HT-LT zone

Aerobes SRB

SOB

EDX-spectrum

High sulfur content

Harbor piles

Failure of steel sheet pilings in a quay lock

Problem:- Fast corrosion- Holes with several diameters in quay wall- Unexpected mass loss

Action:Coupons were cut out of structure for microbial analysis and material related failure analysis

Type of microorganism or metabolism

Sample IRB IOB SRB SOB APB SF

#1 + - + + + +

#2 + + - + + +

#3 + - + + + +

#4 + + - + + +

Results of detection of corrosion relevant microorganisms; the color code indicates activity of microorganisms, green= low

activity, orange= moderate activity, red= high activity, + = growth present and - = growth absent.

Failure of steel sheet pilings in a quay lock

Location Sulfur [wt%]

Box 2 3.5

Box 3 4.2

Box 4 6.3

SEM-EDS results of metal coupon cut out of the steel sheet pilling of the quay lock.

Upper line: left= cross section of the metal coupon, right= EDS elemental mapping showing distribution of sulfur;

Middle line: left= overlay of images from cross section and elemental mapping, right= marking of analyzed area shown in EDS spectrum;

Lower line= EDS spectrum of analyzed area

SEM-EDS results from metal coupon cut out of the steel piling wall in the quay lock. Blue boxes indicate different positions of analyses, sulfur values are listed in the table.

MIC present and responsible for high mass loss

How can WE win this Battle???

Microbial Corrosion activities

Diagnosis and risk assessment Microbial presence/activity Microbial corrosive metabolites Characterization of corrosion damage

(electrochemical, metallographic)

Microbiology

Metallurgy

Direct observation (in-situ analysis)

Electrochemistry MIC

Monitoring In-situ, online detection

techniques Offline analyses

Mitigation (prevention and treatment) System design recommendations (e.g., material selection, substrate pre-treatment, coatings, anti-

microbials, etc)

What can we do about diagnosis?!

MIC diagnosis

Case documentation

Microbial analysis (growth- & DNA

based)

Microbial related failure analysis

Exclude other corrosion

mechanisms

• Case documentation (put available data in the right context) • Combine microbial analysis & microbial related failure analysis to collect

evidence of microbial presence and activity directly at the affected material surface

• Sampling should be done by trained person to exclude cross contamination

Case documentation

MIC diagnosis

Microbial detection methods: growth based techniques

Growth on selective media for corrosion relevant microorganisms Enriched cultures can be used for further corrosion tests

Disadvantages:- Only 1% of environmental microorganisms are cultivable- Microorganisms from extreme environments are difficult to grow- Selective bias can bring misleading results- Need days/ weeks for incubation

MIC diagnosis

Microbial detection methods: DNA based techniques

Quantitative polymerase chain reaction (q-PCR)

Several other techniques possible Requires no cultivation Fast results, hours instead of days/ weeks Even microorganisms from the extreme environments

can be detected

Disadvantages:- Target genes have to be known before analysis- Target gene not present for all relevant microorganisms

or activity genes

MIC related failure analysis

Analysis of corrosion products and microbial metabolites using SEM-EDX, photometric or chromatographic methods

MIC related failure analysis

3D microscopy: Pit depths, pit shape/ geometry

MIC related failure analysis

Visualization of microorganisms attached to the material EFM, AFM combined with fluorescent stain binding to DNA; live/ dead staining

Microscopic techniques to detect microbial presence

and activity directly at damaged spots

MIC related failure analysis

Exclude other corrosion mechanisms !

Galvanic corrosion

Stray current

- Often other corrosion mechanisms are not taken into account Failure in the choice of the correct mitigation strategy

- “Chicken or the egg” question: what was first?!Wrong choice/ failure of the material or presence/ activity of microorganisms

- Often MIC occurs combined with other corrosion mechanisms:

What can we do about diagnosis?!

MIC diagnosis

Case documentation

Microbial analysis (growth- & DNA

based)

Microbial related failure analysis

Exclude other corrosion

mechanisms

MICYes or no?!

Things to keep in mind:

• MIC needs to be analyzed on case by case basis

• Other corrosion mechanisms need to be excluded

• Prove not only the presence but also the activity of MIC relevant microorganisms

• Put all collected data/ evidence in the correct context

• Choose the correct transport and storing conditions

• Think about prevention strategy before structure is installed

• Choose the correct mitigation strategy once MIC is detected

• There is not one “powerful tool” against MIC, it is a combination of many factors such as:

- correct choice of material- planning & set-up of the structure/ system- cleaning of the system - availability of nutrients...

Bevesierweg 1 DC0021781 AT Den HelderP.O. Box 5051780 AM Den HelderThe Netherlands

0223-747001

www.endures.nl

Thank you for your attention!