Impact of Biofilm and Biofouling on materials and processes

Objectif

A. Background

COST Action 511 entitled "Interactions of microbial systems with industrial materials" was active from 1992 and will expire at the end of December 1996. A new Action entitled "Biofouling and Materials" is proposed. This new Action will cover deterioration processes induced by the presence of microorganisms on materials surfaces as well as negative impacts on processes due to the development of a biofilm.

The work within COST 511 considerably improved the understanding of many aspects of the deleterious effects of microbial systems. Nevertheless, many questions related to biofilms and their impacts on materials are still not understood today, or appropriate countermeasures are not yet known, and for these reasons necessitate further research effort in the future.

Based on the achievements of COST 511, the anticipated new Action on "Impact of biofilm and biofouling on materials and processes" will focus on the goals described in the following text. This new Action will strongly guide basic research, support knowledge transfer and industrial application of the results.

Impacts of biofilm and biofouling on materials and processes:

The growth of biofilms is observed on all surfaces being in contact with water or moisture. Negative effects of biofilms are e.g.

-the deterioration or corrosion of materials,

-fouling on surfaces of industrial equipment reducing heat transfer in heat exchangers, plugging of tubes, determination of hygienic conditions in systems (e.g. in air-conditioning equipment or in the clean air technology),
-the increase of friction on rapidly moving objects (e.g. development of biofilms on ship hulls or in water transport systems),

-gas formation and evolution due to corrosion or other biological processes may lead to pressure increase in closed systems and create a serious risk of failure (e.g. in nuclear waste disposal repositories).

Environmental significance:

Fighting biofilm and biofouling involves, as a standing practice, the use of chemicals and toxic biocides. National and international environmental regulations will restrict increasingly the use of toxic chemicals. Since the phenomena involved are often poorly understood, biocides are empirically supplied, rendering the dosage often too low to be effective, or unacceptably high. Furthermore, the adoption of a holistic view of the process, including design, raw materials, maintenance is widely neglected. An improved understanding of the process could considerably increase the efficiency and the environmental compatibility of countermeasures.

B. Objectives and Benefits

The scope of the COST 520 programme is concentrated on only a few, but important, focal points within the vast field of biofilm between the biofilm and industrial surfaces. These are:

(a)The development or the improvement of appropriate methods in order better to characterize biofilms, their interactions with materials surfaces and biocides.

The methods considered for characterization will use among others advanced microscopic (e.g. atomic force microscopy) or spectroscopic (e.g. FTIR-spectroscopy) techniques. Such methods will be developed or adapted to the specific conditions found on materials covered with a biofilm. The identification of specific microorganisms causing biofouling will allow their origin to be identified as well as the development of a biofilm to be followed as a function of time and other parameters of their environment (temperature, nutrients, substratum material).

Methods for studying the interactions of microorganisms with the substratum material - e.g. electrochemical polarization techniques, electrochemical noise, galvanic cells, microcalorimetry - must be improved in order to supply unequivocal information on the deterioration process (e.g. corrosion).

All these methods are expected to supply the basic knowledge for the development of control and monitoring devices to be used under practical operating conditions of a plant or a process.

(b)The improvement of the knowledge on the surface accumulation of microorganisms, on their adhesion and aggregation into a biofilm and on the structure and function of biofilms

FTIR techniques will be used to determine the chemical nature of the film. Furthermore, enumeration and assessment of the metabolic activity of the biofilm population will be carried out. Specific relevant groups of microorganisms will be identified and quantified by the MPN method and possibly by 16S-RNA gene probes (molecular biology method). Microcalorimetry will be employed to determine the metabolic activity of microorganisms. Chemical analysis of extracellular polymeric substances (EPS) by calorimetric methods, chromatography and gel electrophoresis will be used. Thus, the presence and quantity of these compounds may be determined and correlated with the corrosion process.

(c)Better to understand and to be able to influence their interactions with the environment and in particular with materials, including their protective measures.

It will be indispensable in the future better to control deleterious effects of microorganisms and biofilms on materials and processes in order to make optimal use of raw materials and energy, to reduce maintenance costs and shutdown time of plants, and to eliminate hazardous risks to health and goods.

The efficiency of protective measures must be increased. Emphasis will be given to the development of biocides which are harmless to human beings and to the natural environment. The safe, ecological and economic use of protective measures will require accurate monitoring of microbial processes and the development of biofilms.

The new Action shall focus on the same scope and fields of interest as COST 511. COST 511 dealt with biofilms, water systems, metallic and organic materials, methods and antimicrobial strategies.

The anticipated COST Action 520 shall also include, because of the general relevance to industry and society

-microbially influenced corrosion (MIC) and biofilm interactions on surgical implants, -nuclear waste repositories,
-soil,
-oil and gas industry,
-concrete, bricks and glass,

as well as interactions with the environment. These fields have been recognized to be relevant and to fit in the general scope of the new Action.

The following industries have been identified as potential users of the results from the new Action:

- steel producers- plastic producers
- coating producers- producers of chemicals for water treatment
- nuclear and power industry- paper industry
- oil and gas production- oil refinery
- petrochemistry- naval construction
- harbour maintenance- medicine (sterilization, implants, instruments)
- water industries including- dentistry
< industrial water- food and drug industry
< cooling water- electronics (ultra clean laboratories)
< drinking water- air conditioning (building, industry, cars).
< waste water

The attraction of projects on biodeterioration of polymers and organic coatings will receive special attention, since additional research is needed for satisfying problem solutions.

In COST 511, a very good link between research centres and universities has been established; nevertheless, it has been recognized that there is a need for closer cooperation with industry. This will help in achieving one of the most important goals which was relevant for COST 511 and which will also be valid for the new Action: to provide solutions for a prolonged service life of goods and equipment, reduce the consumption of raw materials and energy as well as negative impacts on health and environment.

C. Scientific Programme

In the course of COST 511, the cooperation of various European specialists resulted in a better understanding of basic processes. As a consequence, it was possible to pose a number of relevant questions the answers to which would permit an improvement of countermeasures. These include:

-What are the possibilities of limiting biofilm and biofouling effects without biocide?

-What biocide is the most effective against biofilm and biofouling?

-What is the relation between microbially influenced corrosion and (drinking) water characteristics?

-Function of extracellular polymeric substances (EPS) in primary adhesion: do they constitute an indispensable element or are they merely a carbon sink?

-Is there a need to specify biofilms according to their structure and metabolism?

-What are the primary effects in microbial adhesion to interfaces?

-What happens in the exopolymer-layer between the cell wall of a microorganism and the surface of a material?

-Why do bacteria attach to a given site on the surface of a material?

-How can we measure and quantify the adhesion and the mechanical stability of biofilms?

-How to identify and simulate the corrosion causing conditions at interfaces?

-What are the limits of the currently available modelling programmes?

In COST 511, the transfer of knowledge on processes related to microbially influenced corrosion from basic research to industrial application was considered to be an important goal of the Action. This transfer shall receive increased attention within the new Action.

To achieve this goal, it is planned:

-to build-up and disseminate knowledge on microbially influenced corrosion to industry and public agencies, highlighting the importance of a holistic approach to the problems;

-to propagate the relevance of microbially influenced corrosion in specific fields, e.g. power generation, nuclear waste disposal, concrete and bricks;

-to disseminate information and guidelines related to:
- preventive measures
- monitoring of biofilm growth and related corrosion processes
- maintenance and
- adequate design of equipment

-to establish contacts to manufacturers and suppliers of "chemicals" (e.g. biocides) to allow them to develop and market more efficient and environmentally compatible biocides.

Since large deficiencies in the education of decision-makers exist with regard to problems related to microbially influenced corrosion, these persons in particular shall be addressed in the course of the new Action.

In this context, links to new and existing COST Actions, where MIC and biofilm are relevant (e.g. COST 509, 514, 518, and 519), are considered. Links to the COST Action E1 have already been established in the past and these contacts should be enforced.

D. Organisation and Time Table

The Management Committee (MC) of the new Action will be organized and operated according to the document COST 400 "Rules and Procedures". Links will be established to other COST Actions, where MIC and biofilm are expected to be relevant.

As for COST 511, workshops will be organized on an annual basis where project leaders are invited to present their annual progress report.

Depending on the number and the themes of the incoming project proposals, Working Groups focusing on defined specific areas, in which biofilms are relevant, will be formed. Work packages listed subsequently are preliminary and are based on the work of experts:

-industrial water systems,
-marine environments,
-nuclear waste disposal sites,
-stone and concrete,
-antimicrobial strategies (biocides).

It is suggested that the proposed Action be carried out for a period of five years (1997-2001) and organized as follows:

-year one: call for proposals and definition of coherent objectives between the COST partners,

-years two to four: coordination of principal research and development efforts,

-year five: synthesis of the work accomplished so far and adjustment of the research objectives.

This proposed duration of the Action seems to be adequate for the following main reasons:

-the growth of biofilms as well as the corrosion processes which may be induced by these films are time consuming processes, which in general cannot be speeded up without the risk of changing basically the processes involved;

-many (field) tests can only be performed during the warm season (e.g. field tests in industrial cooling systems), reducing the time available for experiments by approximately 50%;

-the transfer of achievements from research into relevant and appropriate literature in order to increase the awareness of people concerned with MIC and biofilm problems is a time-consuming process.

E. Economic Dimension

Loss of precious raw materials, loss of energy and negative effects on health, safety and the environment are the results of these interactions.

It is generally agreed that per annum losses between 2 and 4% of the GNP are caused by corrosion of consumer and industrial goods. Estimations indicate that microbial processes are directly or indirectly responsible for about 30% of these losses.

Today it is admitted that microbial processes are much more often the cause of corrosion damages than was assumed in the past. The reasons for this increased acceptance are a better understanding of the processes involved as well as the availability of improved and specific tools required for the study of complex microbial processes. This new understanding and these improved tools are evidently the results of the increased research in the last years in the field of microbiological deterioration of materials.

From the experience gleaned from COST 511 one may conclude that industry is not sufficiently aware that biofilm or MIC may be a serious problem in their specific field of activity. In the new Action, a special attempt will be made to motivate industry to participate more actively.

The following countries have participated in the COST 511 Action:

Belgium, Bulgaria, Finland, France, Germany, Hungary, Italy, Spain and Switzerland.

All these countries have actively participated in the preparation of the new Action or have otherwise indicated their interest. Furthermore, a strong interest in the new Action was demonstrated during the final COST 511 Workshop in Budapest in May 1996 by researchers and representatives from industry from Sweden and from the United Kingdom.

On the basis of national estimates, the overall costs of the activities to be carried out under the new Action was estimated, in 1996 prices, to be approximately ECU 12 million for the five years duration. This corresponds to an effort of approximately 25 man/years per year.

This estimate is valid on the assumption that all the countries mentioned above will participate in the Action. Any departure from this will change the total costs accordingly.

Programme(s)

IC-COST - European cooperation in the field of scientific and technical research (COST), 1971-

Thème(s)

2 - Metallurgy and Materials Sciences

Appel à propositions

Data not available

Régime de financement

Data not available

Coordinateur

N/A

Contribution de l’UE

Aucune donnée

Adresse

Allemagne

Coût total