Current knowledge on microbial induced problems and biofouling in lubrication systems of ships and marine installations (2)

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FRAS Technology AS, Industrial Microbiology Reviews nr 1. 2013

Current knowledge on microbial induced problems and biofouling in lubrication

systems of ships and marine installations

Christer Moe Fjeld

FRAS Technology AS Kongeveien 30 1430 Ås, Norway

Summary

Microbial induced problems (MIP) and biofouling in lubrication oil systems are probably rare and usually

an occult event. MIP and biofouling are in most cases assumed to be of mechanical origin and mitigation

is undertaken without knowledge of the underlying cause. Because of this, the extent of such problems

is not known, but assumed to be rare. Based on the ubiquitous nature of microorganisms and their

versatile arsenal of metabolic properties, it is not surprising that they are capable of causing detrimental

effects in a wide variety of industries. Industries using oils for lubrication purposes are no exception. If

water is present and the water activity is sufficient, the systems are prone to microbial colonization,

which may in turn result in several adverse effects. Lubricants and especially spent lubricants, are toxic

to many organisms, thus environmental challenges are indeed a legitimate concern. These days, several

industries that are using oils for lubrication purposes are shifting to a “green” line in their choice of

fluids. In industries such as forestry and other terrestrial applications, these lubricants are excellent

replacements to the petroleum based lubricants. However, care should be exerted in maritime

industries since water will usually be found in various amounts in the lubrication systems. The

Environmentally Acceptable Lubricants (EAL) are more biodegradable than the traditional oils based on

petroleum. Therefore, it is reasonable to assume that these fluids are more prone to biodeterioration in

the lubrication systems. Because of the higher biodegradability of the EAL, there is a risk that microbial

induced problems and biofouling will increase in the future. This emphasizes the importance of

increased monitoring of such problems in the marine industry. In this review, I used reports from FRAS

technology AS and the current literature with the aim of trying to explain some of the reasons for

unknown machinery breakdown. In addition, I present some cases where microorganisms are the cause

of machinery breakdown, either directly or indirectly.

Key words: Petroleum based lubricants, environmentally acceptable lubricants, additives, biofouling

Correspondence: [email protected] Kongeveien 30, 1430 Ås, Norway

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1. Introduction

Microbial growth is not as solitary and simple as one would believe. Microbial growth and

colonization is complex, involving social interactions, synergistic cooperation, intense

competition for nutrients and a very large microbial diversity over a very small area. The

presence of active and proliferating microorganisms are ubiquitous in nature, including sodium

chlorine brine water (cryopegs) at sub zero temperatures in the Antarctic (Gilichinsky, et al.,

2005) and in the vicinity of hydrothermal vents on the oceans floor where microorganisms are

proliferating in temperatures at around 121oC (Kashefi & Lovley, 2003). The strain identified by

Kashefi and Lovley was also able to grow at an astonishing 130oC. Microorganisms are also

found in acidic and alkaline environments. The general requirements for microbial growth to

occur is the presence of free water (or a water activity aw > 0.85 for most microbes), a carbon

source (glucose, cellulose, hydrocarbons, lipids, proteins etc), for the heterotrophs and CO2 for

the autotrophs, and various amounts of nitrogen and phosphorous depending on microbial

species (oligotrophic organisms are able to grow in very pure water e.g. Caulobacter sp.) In

addition microorganisms require micronutrients such as sulfur, iron, manganese etc for optimal

growth. The key factor involved in biodegradation is usually the bioavailability of compounds

with a few exceptions such as polycyclic aromatic hydrocarbons (PAH) due to higher water

solubility than many long chain alkanes (Huesemann, et al., 2004). In general, hydrophilic

compounds have a higher bioavailability than hydrophobic compounds (Bosma, et al., 1996).

When microorganisms are in contact with a moist surface, they will attach. After some time

(hours to days depending on environmental factors and species present) they will form a

complex 3D structure composed of extracellular polymeric substances (EPS; carbohydrates,

lipids, proteins and DNA), cells and water (Costerton, 1995, Sutherland, 2001, Hall-Stoodley, et

al., 2004). This is referred to as a biofilm. Dental plaque is a good example of a typical biofilm.

Cells that are imbedded in the EPS matrix are provided with both shelter from predation,

antimicrobial agents, chemical stress and UV radiation (Carpentier & Cerf, 1993, Lewis, 2008,

Flemming, 2009).

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Another benefit of living in close proximity in biofilms is the facilitation of metabolic

cooperation between different species (Costerton, 1995), However, strong competition also

occur (Elias & Banin, 2012). Biodegradation of complex organic compounds such as

hydrocarbons is often more efficient in biofilm cultures compared to planktonic degradation of

hydrocarbons (Jain, et al., 2011). With this short introduction into microbial processes in nature

it is easy to understand that microorganisms are able to cause adverse effects in a wide variety

of manmade applications. When biofilms are established in undesired locations in manmade

applications it is referred to as biofouling, i.e. a biofilm in the wrong place. Biofouling has been

identified as a cause of severe adverse effects in a wide variety of industries (Table 1).

Table 1. Industries and applications known to be adversely affected by microbial induced problems and biofouling

Industry or application Manifestation of problems References

Petroleum industry Microbial influenced corrosion (MIC) and souring of applications and crude oil respectively.

(Neria-González, et al., 2006, Gieg, et al., 2011)

Shipping industry MIC of ships hulls, Increased drag and spread of non indigenous species through ballast water.

(Holm, et al., 2004, Drake, et al., 2007)

Paper industry Product withdrawal, increased maintenance costs and machinery downtime.

(Klahre & Flemming, 2000)

Metal working industry Reduced properties of fluids and, the development of hypersensitive pneumonitis in workers and various dermatological symptoms

(Kreiss & Cox-Ganser, 1997, van der Gast, et al., 2001, Lucchesi, et al., 2012)

Hydroelectric power plants Increased friction in lower vane bearing bushings.

(Schneider, et al., 2006)

Medical applications Biofilms on prosthetic joints and other implants causing infection. Biofilms in hospital environments may cause nosocomial infections.

(Zimmerli, et al., 2004, Lindsay & von Holy, 2006)

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Biofouling and microbial induced problems (MIP) in lubrication systems in any industry are

directly associated with the presence of free water in the systems (aw > 0.85). This is the main

reason why emulsion type metal working fluids (mixture between oil and water) are especially

prone to severe microbial contamination and the resulting detrimental effects (Mattsby-

Baltzer, et al., 1989).

Water may enter the hydraulic/ lubrication systems via three independent routes:

1. Oil storage barrels are often stored outdoors and on the deck of ships. Water spray from

the sea will definitely contain hydrocarbon degrading organisms, independent of

geographic location. Ambient temperature fluctuations will cause pressure and vacuum

shifts of the air in the barrel’s head space. Water with hydrocarbon degrading organism

will enter the barrels through the sealing if water is present on top of the barrels.

2. Humidity in the air may precipitate in lubrication oil tank and humid air could also be

dissolved in the oil and precipitate in cooler areas of the system, such as in ships

thrusters or in stern tubes.

3. Water is frequently introduced to systems through heating and cooling events during

operation, pressure fluctuations as a result of propeller movement and as a result of the

vessel’s movement in the water column. I.e. stern tubes and thrusters will experience

pressure variation due to waves, resulting in a shifting water depth around the

propeller. To compensate for this pressure variation and thus to prevent severe water

ingress, pressure is applied to the systems. This overpressure leads to lubricant loss

when the surrounding pressure is below the pressure applied on the system. This occurs

for example when the propeller is surfacing during rough seas. However, no water

ingress is difficult to achieve.

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To my knowledge, scientific literature on biofouling in systems using oils for lubrication

purposes has been absent for nearly two decades. Some work, however, was undertaken in the

1970`s, 80`s and early 90`s regarding microbial growth in lubrication systems (Summers-Smith,

1982, Okpokwasili & Okorie, 1988, Stuart, 1994-1995). The extent of such problems these days

is therefore unknown. One of the reasons could be that the manifestation of biofouling in such

systems is easily confused with mechanical issues. Previously, the industries were more post

active, after problems occurred, with water drainage of systems and other maintenances

necessary to mitigate the occurring detrimental effects. Upon opening of systems they would

probably observe large quantities of slime, notice foul odor etc, which cannot be explained by a

standard mechanical approach. Such observations would lead to suspicion towards microbial

contamination. Nowadays, however, systems are under more thorough surveillance, thus the

industries are more proactive in avoiding adverse occurrences, especially with emphasis on

water contamination and increased wear (commonly measured by particle count according to

the SAE AS 4059 standard). Therefore biofouling and the following MIP in such systems are

most likely evolving more slowly, based on the small body of water compared to the bulk

amount of lubricant. I.e. the amount of water present is not sufficient to promote extensive

growth with rapid manifestation of detrimental effects. On the other hand, biofouling could

speed up the expected mechanical wear of systems, by facilitating emulsification of oils,

foaming and sludge formation. Relevant questions are, therefore: Have any shipping companies

had a higher maintenance cost than predicted in some vessels? Are there any plausible

explanations for this possible increase in maintenance cost? Does any company report

malfunctions or incidences which cannot be explained by a standard mechanical approach? If

no mechanical or technical explanation can explain the condition, microbial causes should be

considered. Fuels on the other hand are well known to contain harmful microorganisms and

their associated problems. Therefore, biofouling and MIP have for a long time been known in

the fuel industry and accepted as a cause of numerous machinery breakdowns and are thus

especially monitored in the aviation fuel industry (Gaylarde, et al., 1999, Itah, et al., 2009,

McFarlane, 2011).

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Microbial growth in jet fuel has even been identified as the primary source of a plane crash in

1958. This was caused by fuel filter clogging in a B- 52 bomber (Rauch, et al., 2006).

This review highlights the current literature on biofouling and MIP, reports from FRAS

technology AS and my own experience working with biofouling and MIP in lubrication and

hydraulic applications from the maritime and offshore industry. Also included in this review is

the new paradigm in lubricant technology, namely the EAL, also referred to as Ecolabel

lubricants. From a microbial point of view, the EAL could be more prone to biodeterioration in

systems, during operation, based on their environmentally friendly chemistries. Therefore, are

there any reasons for additional concern emphasizing systems and fluid integrity using the EAL?

2. A wide variety of organisms are capable of colonizing lubrication systems.

The marine environment is abundant in microorganisms, typically in the range of 107- 109

organisms L-1. Microbial numbers in the marine environment will vary greatly depending on a

variety of factors. E.g. microbial numbers will be relatively low in oligotrophic (nutrient

deprived) waters such as in the middle of the Pacific Ocean to very high in eutrophic (nutrient

rich) basins or river outlets. In this review, the focus is on organisms which are able to degrade

petroleum hydrocarbons, the EAL and additives. However, other organisms unable to degrade

the lubricants (petroleum based and environmentally acceptable chemistries) or additives could

also be able to colonize such systems. This requires that they are able to utilize metabolites

derived from lubricant and/ or additive degradation, and display tolerance against toxic

petroleum hydrocarbons and additives. Since the EAL are significantly less toxic and more

biodegradable, it is reasonable to assume the presence of a higher microbial diversity, capable

of degrading the EAL, additives and the metabolites produced.

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2.1. Chemistries and biodegradation of petroleum based lubricants.

The petroleum based lubricants are a mixture of hydrocarbons derived from the refining of

crude oil. The hydrocarbon groups found in lubricants are alkanes (paraffins), branched alkanes

(isoparaffins), cycloalkanes (Naphthenes) and aromatics. The abundance of the different groups

varies considerably, depending on the specific application where the lubricant is to be used

(Anderson, et al., 2003). The abundance of aromatics, however, is usually minimized, due to

some undesired properties of aromatics, such as poor oxidation stability and carcinogenicity.

Because of the different compounds in crude oils, base stocks used in the formulation of

lubricants are classified according to the American Petroleum Institute (API).

The criteria according to API are summarized in table 2. API group II and III are the most

oxidation resistant, with the latter being the most resistant (Sharma & Stipanovic, 2003).

Table 2. API classification of lubricant base stocks

API group Saturates (%) aromatics (%) Viscosity index sulfur (%)

I < 90 > 10 < 120 > 0.03

II > 90 < 10 80- 120 < 0.03

III > 90 < 10 > 120 < 0.03

Adapted from Sharma & Stipanovic, 2003

In general, the biodegradability of hydrocarbons follows in decreasing order; alkanes,

isoalkanes, low molecular weight aromatics, cycloalkanes and polycyclic aromatic hydrocarbons

(PAH`s) (Huesemann, 1995). Another important factor in the biodegradability of lubricants is

the viscosity. Low viscosity oils are in general more biodegradable than the high viscosity oils

(Haus, et al., 2004). Hydrocarbon degrading microorganisms are ubiquitous in nature (found in

soil, water and sediments all over the globe) and include bacteria, archaea, fungi and some

algae (Röling, et al., 2003, Antić, et al., 2006, Head, et al., 2006).

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Hydrocarbon degradation also occurs deep down in oil reservoirs if the temperature is below

90oC (Philippi, 1977, Magot, et al., 2000). Also, evidence indicates that heavy crude oil (rich in

resins and asphaltenes) is a result of biodegradation of the lighter hydrocarbon fractions (Head,

et al., 2003). Hydrocarbon degradation also occurs at subzero temperatures (Rike, et al., 2003).

Various hydrocarbons enter the environment naturally through reservoir seepage, incomplete

combustion of wood and plant secretions of waxes. These natural sources have been

introducing hydrocarbons into the biosphere over millions of years, and microorganisms have

adapted to metabolize these energy rich substances. Microbial hydrocarbon degradation is

initiated via four principle routes. The most efficient way of degrading hydrocarbons is to

enhance its surface and water solubility. This is achieved through the production of

biosurfactants, resulting in emulsification of hydrocarbons, thus increasing its bioavailability

(Bouchez Naïtali, et al., 1999). This way of initiating biodegradation of petroleum hydrocarbons

in addition to the sorption capacity and high cell density is probably one of the reasons for the

increased extent of biodegradation seen in biofilm cultures (Singh, et al., 2006, Jain, et al.,

2011). Organisms in the biofilm matrix may generate higher amounts of biosurfactants

compared to the planktonic population, thus some biosurfactants are important components of

the EPS in the biofilm matrix (Flemming & Wingender, 2010). Oil emulsions are consequently

one of the leading causes of MIP. Emulsions formed will easily clog filters nozzles and valves.

Also, if such emulsions are transported between load carrying surfaces it could lead to loss of

lubrication film resulting in excessive friction. Other strategies to access hydrocarbons are;

micrometer sized droplets dispersed in the water column, direct attachment to oil slick/

droplets and degradation of the water soluble hydrocarbon fraction. The latter yields low

amounts of biomass as the water solubility of hydrocarbons is very low. As an example, the

solubility of hexadecane in water is 0,029mg L-1 (Bai, et al., 1997). The water solubility of

saturated hydrocarbons decreases with increasing molecular weight. Reasons for the well

recognized problems with biofouling and MIP in the fuel industry is that diesel, for example,

consists of a lighter fraction of hydrocarbons and is thus more biodegradable than lubricants

which consists of a heavier petroleum fraction.

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On the other hand, the lightest petroleum fraction used in fuels e.g. petrol, is not as

biodegradable due to membrane toxicity of these low molecular weight hydrocarbons

(Sikkema, et al., 1995). Also, gasoline separates quickly from water, whereas diesel fuels tend to

retain and disperse more water than gasoline, thus there is a higher surface/ volume ratio in

which microorganisms can initiate their attack (unpublished observation). Historically, the

fraction that has been reported to be the most vulnerable for microbial attack is the fraction

with boiling range between approximately 150- 400oC (middle distillate) (McFarlane, 2011).

2.2. Chemistries and biodegradation of additives.

To compensate for weaknesses or enhance other properties of the fluids, a wide variety of

different chemicals are added to the lubricating fluids. The additives of such fluids include pour

point depressant, antioxidants, anti wear agents, viscosity index improvers, rust inhibitors,

defoamants, detergents and dispersants. The additives are typically organic and metallo-

organic compounds. This class of compounds in lubricants has received very little attention

regarding microbial degradation. In fuels, however, additives have been shown to be vulnerable

to microbial attack (Gaylarde, et al., 1999). Many of these compounds contain nitrogen,

phosphorous and sulfur, which are important elements for growth. As an example, anti wear

agents are important additives in lubricants whose role is to form a protecting film on

components of the system. These anti wear agents are usually based on organophosphates,

such as triphenyl phosphorothionate (Mangolini, et al., 2011). This group of compounds is

readily degraded by a wide variety bacteria and fungi. In general, organophosphates (e.g. tri- n-

butyl phosphate) are toxic to algae but not bacteria (Michel, et al., 2004). Antioxidants are

another important additive, which typically contains amines and phenols. Emphasizing the

important role of additives and their vulnerability to microbial attack during usage, the

biodegradation of these compounds should be studied in more detail. The additives of the EAL

must also have a higher biodegradability than the additives used in petroleum based fluids. It

raises additional concerns using even more degradable additives.

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This is especially true when the role of the additives is to compensate for weaknesses in the

base fluid. For example, the degradation of viscosity index improvers would certainly reduce

the properties of the fluid during either cold or hot operational temperatures. Deterioration of

additives could therefore lead to severe reduction of important properties of the fluids

(lubricity, hydrolytic and oxidative stability etc). Also, based on their chemistry the additives

might serve as a source of phosphorus, sulfur and nitrogen, which could speed up the process

of hydrocarbon degradation or the deterioration of EAL.

2.3. Biodegradation of EAL

The whole idea of the EAL is their low- toxicity and their high biodegradability compared to the

petroleum based lubricants. For the lubricant to be considered as environmentally acceptable it

has to be more than 60% biodegradable in 28 days at 25oC. The biodegradability is determined

using the OECD 301B and 301D, CEC -L-33-A-94, EPA 560/6-82-003 and ASTM D-5864 test

protocols. The biodegradability is measured as a mean of ultimate (substances is converted

CO2, water and biomass) or primary degradation (modification of physical chemical properties

of the substance). Because of the lower toxicity and higher biodegradability compared to

petroleum based fluids, it is likely that a larger microbial diversity is able to degrade these

fluids. Also, microbial degradation of the EAL will most likely occur at a higher rate and extent,

thus causing problems earlier than microbial degradation of petroleum based lubricants. That

is, if and only if, water is present in sufficient quantities. In addition, the new criteria for the

next generation EAL are that it must contain a minimum of 50% renewable materials, according

to the EPA 800-R-11-002 standard. In this review, however, I will discuss the base stocks for EAL

approved at present time. It is also worth mentioning that fully formulated EAL could be a mix

of different base stocks. A common blend of base stocks is for example polyalphaolefins mixed

with vegetable oil.

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2.3.1. Polyalphaolefins (PAO`s)

This class of lubricant is synthesized from olefins (alkenes) found in petroleum and usually with

ethylene to form saturated branched hydrocarbons i.e. isoalkanes. The PAO`s are therefore not

biobased and It has the lowest bioavailability of the EAL based lubricants. The PAO`s are

equivalent and even have some superior properties over the petroleum based fluids, such as

excellent oxidation and hydrolytic stability. Compared to the petroleum based lubricants, the

PAO`s are significantly more biodegradable (at least the lower viscosity PAO`s) even though

alkanes are in general more biodegradable than branched alkanes. Based on the chemistry of

the PAO, the initial biodegradation process involves enzymes related to hydrocarbon

degradation such as monooxygenases and dioxygenases (van Beilen & Funhoff, 2005, van

Beilen, et al., 2006). The microbial diversity capable of degrading the PAO`s may therefore be

somewhat similar to the diversity able to degrade petroleum hydrocarbons, especially those

organisms that are able to degrade alkanes, isoalkanes and cycloalkanes.

2.3.2. Triglycerides (plant oils)

These EAL are based on plant oils, such as rapeseed or castor oils. The triglyceride based

lubricants are the most biodegradable base stock. This is primarily due to a higher

bioavailability of such oils, and a larger diversity of microorganisms able to degrade triglycerides

compared to petroleum hydrocarbons. After all, fatty acids are found in every cell in the

biosphere, and most species possess pathways for fatty acid degradation e.g. β- oxidation.

Another challenge regarding vegetable oils is their low oxidation stability and low hydrolytic

stability. Therefore, vegetable based lubricants is suitable only in low temperature applications

and in open machinery such as chainsaws (Nagendramma & Kaul, 2012). Interestingly, from a

totally environmental point of view, from crop production, using fertilizers, harvesters etc to

use in machinery, with higher turnover of lubricants and spare parts, vegetable oils could have

a higher environmental impact than petroleum based lubricants, except for CO2 emissions

(McManus, et al., 2003).

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The latter citation is nearly 10 years old, thus new additives could have been developed which

could reduce some of the environmental impacts described in their work.

2.3.3. Synthetic esters

Synthetic esters (SE) have been used as lubricants for more than fifty years and have many

desirable properties, including good low temperature characteristics, high viscosity index, high

thermo- oxidative stability, good hydrolytic stability and good anti-wear properties. As base

stock for lubricants, two types of SE are available. These are the diesters and polyol esters and

are composed of dicarboxylic acids and fatty acids attached to an alcohol, respectively

(Nagendramma & Kaul, 2012). SE are readily degraded by microorganisms due to the

ubiquitous nature of esters in the biosphere. The biodegradation involve esterase enzymes

which splits the esters into an acid and an alcohol through hydrolysis (Kawai, 2012).

2.3.4. Poly glycols

Poly glycols or polyalkylene glycols (PG), could be either water soluble or water insoluble based

on molecular weight of the polymer i.e. what precursor it is derived from (EPA 800- R- 11- 002).

The water soluble glycols are the most biodegradable. On the other hand, it is also the most

toxic of the PG. If the recipient is small and lubricant loss is large, the concentration of glycols in

water could be very high and toxic to organisms in its proximity. There is a wide variety of

organisms able to degrade poly glycols, with the low molecular weight glycols being the most

biodegradable (Kawai, 2012). PG is being successfully used in vessels using stern tubes for

propulsion. This type of EAL can also tolerate significant higher percentage water

contamination because it can be water soluble (Sada et al., 2008). However, for thruster

application this type of EAL does not provide sufficient lubricity (Sada et al., 2009).

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3. Cases where microorganisms are a probable cause of machinery malfunctioning in

lubrication and hydraulic systems using mineral based lubricants.

Case 1.

Hydraulic control valves from an oil drilling platform (fig 1) were sent to FRAS technology AS for

failure investigation. The unit was expected to have a duration period of approximately 10

years. After just 9 months the crane which controlled the drilling cone started to respond in an

unpredictable manner.

Upon arrival the unit was opened and the unit interior was found to be completely destroyed

with the presence of elemental sulfur (S0) and aluminum oxide. Obviously, strong galvanic

corrosion had taken place between the steel and aluminum parts of the valve, indicating the

presence of a liquid with good electric conductivity in the valve (in lieu of the hydraulic oil),

such as seawater. The presence of S0 must be considered as a hallmark of an underlying

microbial process in such systems (Tang, et al., 2009). Most likely the sulfur originated from

sulfate via sulfide, which is present in high amounts in seawater.

Figure 1. A. Hydraulic control unit from an oil drilling platform, where microbial processes has

deteriorated its interior. The unit was supposed to endure ten years of operation but this

photograph was taken only after nine months of operation (photo taken by FRAS tech AS). B.

Scanning electron micrograph, showing both coccoid and bacilli shaped microorganisms (with

permission from Elin Ørmen at the Norwegian University of life sciences).

A B

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The mechanism behind the detrimental effects seen in this control unit is beyond the scope of

this review, but it involves very complex chemical reactions initiated by bacteria. However, it is

tempting to propose a short explanation, sulfate reducing prokaryotes (SRP) are strictly

anaerobic organisms, and do not grow in the presence of oxygen. Interestingly, the microbial

conversion of sulfide to S0, requires oxygen. One of the probable scenarios therefore follows;

SRP in anaerobic conditions causes the interior to deteriorate, sealing material is compromised

and the organisms in the unit are exposed to oxygen due to air ingress. This leads to a shift in

the microbial community where sulfide is oxidized to S0 by colorless sulfur bacteria, such as

Thiobacillus sp (Tang et al., 2009). Also possible is the presence of a biofilm which contain both

anaerobic and aerobic zones. This would sustain the simultaneous growth of both the

anaerobic SRP and the aerobic colorless sulfur bacteria.

Case 2.

A ship’s thruster had a breakdown after a long period of downtime. According to the failure

report (pers com CEO Sølve Fjerdingstad at FRAS technology AS and Dr. John Olav Nøkleby at

DNV GL), the malfunctioning was caused by the lack of lubrication, resulting in massive stress

on the mechanical parts. The damaged parts were sent in for mechanical inspection and a slimy

substance was literally pouring out upon opening (fig 2). This slimy material is most likely not of

mechanical origin, but most likely a result of microbial growth. Mechanically produced sludge is

often highly viscous or semi solid and does not behave like a slimy substance, due to the

presence of wear debris, oxidation products and sometimes water. A microbial survey was not

initiated due to late recognition that this could be a microbial problem rather than a technical

issue.

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Figure 2. Slime of microbial origin and emulsified oil pouring out from the bearing part of a

thruster (photo taken by FRAS tech AS)

Case 3.

A supply vessel had been in dry dock for maintenance due to unknown machinery breakdown.

During this maintenance the lubrication oil was most likely not changed, nor was the system

checked for the presence of any free water. Shortly after the vessel was put into operation after

the maintenance procedure, the ship’s lubrication system stopped and the reason was found to

be filter clogging. Since the vessel had been in dry dock for maintenance and no reasons for the

previous breakdown were found, the lubrication oil was drained and the oil sump was

thoroughly cleaned using a steamer. During steaming, flakes of paint loosened from the oil

sump surface (fig 3).

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Surface of the paint flake Yeasts Fungal spores Fungal hyphae

EPS

Bacteria

Figure 3. Scanning electron micrograph showing various microorganisms and a thin biofilm, covering the surface of a paint flake sample (scale bar indicate 2µm).

The engineers responsible for cleaning and maintenance observed material on the surface

which they did not believe had any mechanical or chemical origin. The flakes of paint were sent

to The Norwegian University of life sciences via Fras technology AS for microbial analysis. After

cultivation, nine different bacterial genera were identified in addition to three fungal genera

(Table 3). I will here give a short argumentation for the resulting filter clogging. During dry dock,

the water in the lubrication system was stagnant. This leads to the formation of lose and patchy

biofilms covered with oil emulsions, on surfaces and in the oil/ water interface (Fjeld, 2012

unpublished results). A possible reason for this unexpected occurrence of filter clogging is that

these biofilms with low mechanical stability and bound emulsions will be disrupted when the oil

again is in circulation. Consequently biofilm material and emulsified oil will follow the liquid

flow, until it reached the filters, leading to filter clogging.

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Table 3. Organisms identified from the cultivated oil phase, water phase and biofilm, size of query sequence, similarity with the closest match in the NCBI BLAST database and the proposed taxonomic affiliation of the organisms. Proposed taxonomic affiliation

Query sequence (bases)

Closest match in the BLAST database Max identity (%)

Taxonomic rank

Bacteria

Acinetobacter 1500 Acinetobacter sp GXA5 (AY902243.1) 98% Gamma proteobacteria, pseudomonadales

Shewanella ** 1493 Shewanella sp. W3-18-1 (CP000503.1) 99% Gamma proteobacteria, alteromonadales

Delftia 1495 Delftia sp. LFJ11-1 (DQ140182.1) 99% Beta proteobacteria, burkholderiales Comamonadaceae

Achromobacter ** 1492 Achromobacter sp. MT-E3 (EU727196.1) 99% Beta proteobacteria, burkholderiales

Pseudomonas 1497 Pseudomonas sp. VKM B-2265 (DQ264636.1) 94% Gamma proteobacteria, pseudomonadales

Variovorax ** 1488 Variovorax sp.RKS7-5 16S (EU934231.1) 96% Beta proteobacteria, burkholderiales Comamonadaceae

Chryseobacterium * 1384 Chryseobacterium sp. B2 (EU109732.1) 96% Flavobacteria, Flavobacteriales, Flavobacteriaceae

Serratia * 1492 Serratia sp. GU124497.1 95% Gamma proteobacteria, Enterobacteriales

Bradyrhizobium * 1427 Uncultured Bradyrhizobium sp. clone PSC8 99% Alpha proteobacteria, Rhizobiales

Fungi

Phialophora ** 625 Phialophora sp. WRCF- AB8 (AY618680.1) 100% Ascomycota, Pezizomycotina, Sordariomycetes

Fusarium ** 973 Fusarium solani strain ATCC 56480 FJ345352.1

98% Ascomycota, Pezizomycotina, Sordariomycetes

Phoma **

1024

Phoma sp. GS9N1a (AY465466.1)

100%

Ascomycota Dothideomycetes Pleosporomycetidae

* Organisms only found in the biofilm samples ** Organisms only found in the liquid (oil and water) samples.

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Case 4.

This case is not from the marine or offshore industry but still, it is important in the

documentation of microorganisms that cause problems in lubrication oil systems. A project was

initiated in 1996, called the baktiol (Bakterier I olje, or Bactiol; Bacteria in oil) project, ISBN 82-

576-9804-0. Senior researcher Jon Fredrik Hanssen and Dr. Aaslaug Lode at the Agricultural

University of Norway (NLH), (now the Norwegian University of Life Sciences (NMBU)) initiated a

thorough microbial investigation (Financed by the Norwegian research council and Statkraft

engineering) based on traditional microbial techniques. During that time, new ash less

lubricant additives (additives not containing metals) came into the market and industries were

encouraged to use the more environmentally friendly lubricants. The hydroelectric industry in

Norway noted a sudden increase in maintenance cost due to more frequent oil replacements

and maintenance of machinery in some installations. The hydroelectric industry rarely replaces

their turbine lubricants (pers com Dr. John Olav Nøkleby at DNV). Samples with high particle-

and water content were received from Det Norske Veritas (DNV). The samples were heavily

contaminated (opaque appearance, a lot of wear debris, high water content etc) oil samples

from many different hydroelectric power plants in Norway. Of 67 oil samples, 24 contained

microorganisms based on microscopic examination and culturing. The oil samples that

contained microorganisms also contained free water. If polymerase chain reaction (PCR) based

techniques had been used, the number of samples testing positive for microorganisms would

probably be higher. The organisms isolated included hyphael fungi, yeasts and bacteria. Most of

the isolates were able to grow between 20 and 40oC and some isolates grew well at 4oC. This

study provided recommendations concerning reduction of especially water content but also the

input of air in open oil systems. One drawback of their study was the lack of establishing the

threshold of interference in such machinery. This threshold is very important if correct

conclusions are to be drawn, thus microorganisms does not cause problems until they exceed a

certain number of cells. Microorganisms will for sure be present in water that enters the

systems and hydrocarbon degrading organisms are ubiquitous in nature. Therefore, the finding

of microorganisms in water phase or in oil does not necessarily imply biofouling and MIP.

19


Additional factors that should be addressed if MIP is to be elucidated are the amount of water

in systems, cellular numbers and the presence of events that cannot be explained by

mechanical causes. Nevertheless, biocide treatment and short term follow up resulted in

remission and maintenance cost was reduced, indicating that microbial growth was the cause

of the problems experienced by the industry.

4. Future challenges with emphasis on environmentally acceptable lubricants

EAL are now considered to be the new paradigm in lubrication technology. A large amount of

lubricants are lost to the environment annually, which may have serious ecotoxicological effects

(Michel, et al., 2004). The change into using such EAL has been pivotal for industries such as

forestry and other terrestrial industries where lubricant loss is extensive. Because of

environmental regulations, industries are encouraged into adapting EAL (forced in US waters).

From a microbial and ecological point of view, they are, as already discussed, more

biodegradable and could have less toxicological impact on their surroundings. This fact raises

the question of whether these lubricants will deteriorate at a higher rate in systems during

operation, if the systems have been contaminated with water. It is feasible to assume so, with

reduced operational time and increased maintenance costs (downtime, replacement of spare

parts, cleaning and disinfection) as a result. Biofouling and MIP in the marine industry are easily

confused with mechanical causes and the incidence of MIP is therefore unknown, even with the

use of petroleum based lubricants. Case nr 2 and 3 are good candidates for such confusion as

they were initially reported as machinery malfunctioning of unknown causes. Therefore, there

are reasons to believe that such problems could be underestimated even with the use of

petroleum based lubricants. Bacterial infection of systems could coincide with other

operational and mechanical occurrences. This could lead to a more rapid reduction in

operational time of the systems and compromising of the integrity of the lubricating fluids, than

if mechanical causes were the sole cause for detrimental effects.

20


If the EAL are going to successfully replace the petroleum based lubricants, the industries

should implement a microbial surveillance protocol to monitor and detect any possible

detrimental effects caused by microorganisms. If microbial problems are increasing

dramatically in the future and future environmental regulations are not making an exception

for the maritime industry, new systems design and construction materials should be

considered. I would also recommend a higher degree of cross disciplinary cooperation where

microbiology should be considered if reasons for machinery malfunctioning or other adverse

events cannot be explained by a traditional approach. Indeed, the EAL have replaced petroleum

based lubricants with great success in industries such as forestry with emphasis on direct

environmental impact. Also, synthetic esters have been used extensively as jet engine

lubricants with great success for several decades, due to many superior properties over

petroleum based lubricant. In Forestry a rapid and complete degradation are desirable in

combination with some superior properties of the EAL. It should be noted that care should be

exerted regarding systems in which water is a common contaminant.

5. Discussion and Conclusions

To understand MIP and biofouling in lubrication oil systems we need understanding of the

underlying processes and to acknowledge that microorganisms, regardless of their small size,

are able to cause heavy machinery to break down. The big unknowns in this respect are the

threshold of interference and the extent of such problems in the maritime industry. The

amount of free water is the driving force in exceeding the limit needed for interference.

Microbial growth in systems must be avoided. The best practice to minimize biofouling and MIP

is to have appropriate procedures for oil storage and minimize the amount of free water in

systems. The four cases described were initially reported as unknown cause of machinery

breakdown. This report illustrates that there is a pertinent need for cross disciplinary

cooperation if correct mitigation strategies are to be adapted.

21


To my knowledge, microorganisms are not generally considered as a possible cause of adverse

events in lubrication systems. However, Cases 3 and 4 are the few exceptions where microbial

identification techniques were employed, after other causes had been ruled out. Some

hallmarks of microbial activity in industrial applications include; the presence of slime, the odor

of sulfide (H2S) produced by sulfate reducing prokaryotes (SRP), or other foul odor and

precipitation of sulfur aided by for example Thiobacillus sp (Tang, et al., 2009). From the

experiences with MIP and biofouling in systems using petroleum based lubricants, the problems

usually occur after maintenance or other reasons for machinery downtime. I.e. biofilms with

low mechanic stability is formed during low shear forces, and are easily disrupted when the

system are put into operation with increased shear forces (Stoodley, et al., 2002). Biofilm

material and emulsified oil will follow liquid flow and could lead to clogging of nozzles, valves

and filters and friction increase when trapped between load carrying surfaces.

Also, before adapting the EAL, I would recommend to determine the threshold of interference

for any given system, i.e. how many organisms are required for problems to occur and how

much free water does this require.

Establishing early warning systems is also important to avoid MIP due to biofouling, especially

in systems using EAL. Water control and water prevention actions will therefore be even more

important with the use of the eco label lubricants.

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Current knowledge on microbial induced problems and biofouling in lubrication systems of ships and marine installations (2)