It seems that new methods for P&P microbiology are needed.
After discussions in PulPaper Congress in Helsinki, June 2010, it is obvious that traditional colony count methods cannot tell the truth about process problems.
These methods, originally developed for clinical microbiology, seem to have too high nutrient content. They cannot, therefore, select the "troublemakers" from the process samples. Bacteria like Gram-negative rods and Bacillus sp. are overestimated in these analyses but eg. filamentous bacteria cannot grow on common, commercial agar media.
Identification of bacteria can be important in some cases. Food poisoning species from the genuses Bacillus, Staphylococcus and Clostridia and hygiene indicators like coliforms, E.coli and Enterococci should be found in raw material control in the production of high hygiene products (LPB, other food-grade cartonboards and papers as well as tissue-type products). If not covered by other bacteria, they can be found with CC analyses. PCR also gives a good way to distinct them among other bacteria.
These methods cannot reveal some severe problems, however. Biofilm formation and comparative biocide testing are two types of investigations which cannot be performed with agar cultivations or molecular biology methods. They should be done either in machine trials or simulations. PMEU methods seem to be the best alternatives for rapid evaluation of biofilm formation and biocide testing today because they exclude all artefacts, caused by artificial growth medium (in colony counts) or too high selection of microorganisms (in PCR). CC's and PCR can be adopted to certain tests but when the subject of the study is to see, what happens in the real paper processes, simulation methods like PMEU shall be chosen.
Showing posts with label biocide. Show all posts
Showing posts with label biocide. Show all posts
Monday, June 28, 2010
Saturday, November 14, 2009
PMEU as a tool for biofilm testing
PMEU Method was presented in PIRA Paper Industry Symposium, Barcelona, in October 2009. The basic PMEU model can be applied to diverse test types which help to construct biocide programs for the prevention of sessile and biofilm growth of bacteria in paper machines.
The picture above shows a typical test situation where process water sample, biocide and test coupon (made of steel) are installed in a PMEU syringe. Prevention of sessile growth can be monitored with ATP Assay, biofilm growth with UV Epifluorescence Microscopy.
In addition to the basic PMEU model, the novel PMEU Spectrion which measures the turbidity of all ten samples automatically, can be applied to any microbiological growth / growth prevention test of liquid or slurried samples from paper manufacturing processes. This device can handle also relatively turbid samples because it stops the mixing of the samples before turbidity measurement, allowing heavy particles (like mineral pigments) to sediment and enables therefore the measurement of bacterial cloudiness of the sample.
Sunday, August 16, 2009
Applications of PMEU method for biofilm research and testing of biocides against biofilm growth
Paper machine biofilms have been studied already several years with PMEU method by IM. Test coupons, made of steel brands used in paper machines, have been installed inside PMEU syringaes and the growth has been observed with UV Epifluorescence Microscopy after a short incubation period (see picture above).
This technique has now been modified for ordinary light microscopes, too. Steel coupons have been replaced by specified glass slides and the Gram-stained biofilms can be observed with Bright Field Microscopy - no expensive epifluorescence microscopes are needed in this application.
This method will detect all biofilm-producing microbes and testing of biofilm-preventing biocides is also possible simultaneously. Primary attachers typically appear on the slides in just hours and mature biofilms are available in 12...24 hours. This application is very suitable for all areas of industry where the hygiene of surfaces is important. It can also be applied in every environmental research projects where the formation of biofilms in natural water environments is the subject of the study. Hygiene control of public swimming pools etc. also benefit of this method.
Sunday, July 5, 2009
Connections of paper industry microbiology to other sectors of microbiology: what is actually needed?
To make any definitions of paper industry microbiology, it makes sense to compare it with elder sectors of microbiology. Despite the microbiological problems of the paper processes and the paper products have been obvious since the beginning of machine-scale production of paper and board on 19th century, their effects have get worser when the scale, speed and raw material repertoir have increased during last decades. The tradition of the microbiological control, as well as the history of biocide research, intended in the "healthcare" of paper and board machines is therefore much shorter than in related areas like in dairy or food microbiology.
Paper manufacturing processes could be seen as ecosystems where several, complicated microbiological processes are continuing day and night. Microbial communities perform their important role as the actors of chemical transformations which shall modify most living and very many non-living substances into forms which will support the growth of other living creatures. Many species of immigrant bacteria, coming into the processes with the raw water, mechanical fibres and several additives, will feel fine: favourable temperature, pH level and nutrient concentrations, as well as good aeration and a huge supply of contact surfaces to build up biofilms, are available for them. They really do not make any difference between their lives outside and inside of the paper mill walls.
Unfortunately (not for the microbes but for the paper production) there are some features of paper machines which are similar with fermentor and bioreactor processes of biotechnological industry. So many growth factors (some of them were mentioned above) will be kept on so controlled levels that the adaptation of certain microbiological population cannot be avoided. It shall also be kept in mind that the long running periods will increase the microbiological risks by allowing long growing periods of microbes inside the machines.
How to control these problems?
Measures to dose biocidic compounds into the processes cannot be avoided because the conditions of paper and board machines cannot be adjusted on biocidic levels: the rise of the overall temperature over +80 oC is impossible, like the rise of pH value over 12. Before significant technical improvements to prevent the microbial growth in the paper machine processes could be done (if ever), the biocidic treatments and their rapid control methods like ON LINE biofilm measurements and frequent (at least once per 8 hours) AT LINE microbiological control of the main contaminating routes, wet end processes and towers containing white waters, pulps and brokes are the most important tools to secure the runnability of the machines and the quality of the products.
With the price of only 2-3 jumbo rolls can reliable instruments for the AT LINE microbiological control of the wet end processes be bought today. Alternative methods, many of them representing molecular biology methods, are available, but those which can show not only the counts of certain species but also the overall metabolic activities of the waterborne microbes and their potential to produce biofilms should be preferred. A combination of PMEU incubations and ATP Assays, with the addition of PCR if needed, is the most recommended procedure to show the effects of biocides on the microbial activity. PMEU method can be applied to biofilm testing, too.
The most important thing is that not only the counts of microbes (how high they may ever been) but also their overall metabolic activity and certain actions like breakdown of starches by amylase enzymes or production of H2S and H2 in anaerobic conditions shall be controlled all the time when the machines are running. All the laws of microbial ecology are present both in the nature and inside the machines - and they can lead to severe problems if counteracting does not work.
Paper manufacturing processes could be seen as ecosystems where several, complicated microbiological processes are continuing day and night. Microbial communities perform their important role as the actors of chemical transformations which shall modify most living and very many non-living substances into forms which will support the growth of other living creatures. Many species of immigrant bacteria, coming into the processes with the raw water, mechanical fibres and several additives, will feel fine: favourable temperature, pH level and nutrient concentrations, as well as good aeration and a huge supply of contact surfaces to build up biofilms, are available for them. They really do not make any difference between their lives outside and inside of the paper mill walls.
Unfortunately (not for the microbes but for the paper production) there are some features of paper machines which are similar with fermentor and bioreactor processes of biotechnological industry. So many growth factors (some of them were mentioned above) will be kept on so controlled levels that the adaptation of certain microbiological population cannot be avoided. It shall also be kept in mind that the long running periods will increase the microbiological risks by allowing long growing periods of microbes inside the machines.
How to control these problems?
Measures to dose biocidic compounds into the processes cannot be avoided because the conditions of paper and board machines cannot be adjusted on biocidic levels: the rise of the overall temperature over +80 oC is impossible, like the rise of pH value over 12. Before significant technical improvements to prevent the microbial growth in the paper machine processes could be done (if ever), the biocidic treatments and their rapid control methods like ON LINE biofilm measurements and frequent (at least once per 8 hours) AT LINE microbiological control of the main contaminating routes, wet end processes and towers containing white waters, pulps and brokes are the most important tools to secure the runnability of the machines and the quality of the products.
With the price of only 2-3 jumbo rolls can reliable instruments for the AT LINE microbiological control of the wet end processes be bought today. Alternative methods, many of them representing molecular biology methods, are available, but those which can show not only the counts of certain species but also the overall metabolic activities of the waterborne microbes and their potential to produce biofilms should be preferred. A combination of PMEU incubations and ATP Assays, with the addition of PCR if needed, is the most recommended procedure to show the effects of biocides on the microbial activity. PMEU method can be applied to biofilm testing, too.
The most important thing is that not only the counts of microbes (how high they may ever been) but also their overall metabolic activity and certain actions like breakdown of starches by amylase enzymes or production of H2S and H2 in anaerobic conditions shall be controlled all the time when the machines are running. All the laws of microbial ecology are present both in the nature and inside the machines - and they can lead to severe problems if counteracting does not work.
Wednesday, January 28, 2009
The need of paper machine biocides?
IM is wondering: are there any other sector of process industry, where microbes are allowed to grow like in paper industry?
Biotechnological processes, of course. But their populations are carefully selected and controlled. And they are employers of the company, not criminals trying to cause harm to the company.
Some significant changes in paper industry processes have taken place after the rise of active environmental care. Both the closure of water circulation and the cancelling of biocides having mercury as an active incredient are favorable for the environment, of course. But the microbial growth inside the paper machines has activated at the same time.
The beginning of neutral paper production led to an "ecocatastrophe" inside paper machines. The rise of pH value (as well as the rise of temperature, caused by the extended recirculation of water) was fatal for slow, acid-loving fungal growth. New mineral additives are an important source of certain types of bacteria, causing severe problems like production of slime, spoiling of the process compounds and hygiene faults of the products.
IM has published an article "Paper Machine: an Ecosystem and a Bioreactor" (INOCULA 1/2007. Helsinki, Finland). Many readers agree: paper machines offer ecological niches for bacteria, and the controlled environments of wet end circulations are very much similar with those of biotechnical processes, based on chemostatic fermentors.
A lot could be do to make paper machines more unfavorable growth environment for microbial contaminants. Very good results have been achieved in some projects where ecological aspects have been taken into account. These issues will be discussed later in this blog.
But the main question is: how much biocides we still need to control the microbial growth in all regions of a paper machine?
Incoming raw materials, sorry to say, may be very contaminated: the highest value of total count during IM's career has been over 100 000 000 cfu/g in a mineral slurry (which was fortunately replaced by a fresh lot by the supplier!). It is therefore obvious that a continuous control - both analytical and practical - is needed for starches, mineral pigments and other contaminated raw materials. This does not mean that all lots are spoiled: there are suppliers which know their response to deliver pure products to the mills but all kind of errors in biocidic pre-treatment, transport and storage of these products may happen.
Certain sites of paper machines also need biocidic treatments all the time. Chosing proper solutions for biocide programs (type of biocide, active compound, dosing sites, timing etc.) of a paper machine is a challenging tasks. In best cases, both the paper mill and biocide personnel are sitting down and discussing of the individual problems of the paper process hygiene.
When specified laboratory services, having tools like PMEU and biofilm microscopy, are included, the final result can be optimal one. Paper industry microbiologists can also help significantly by declaring the effects of process parameters on the growth of planktonic and biofilm bacteria.
The more competence is included, the better solution will be find.
Biotechnological processes, of course. But their populations are carefully selected and controlled. And they are employers of the company, not criminals trying to cause harm to the company.
Some significant changes in paper industry processes have taken place after the rise of active environmental care. Both the closure of water circulation and the cancelling of biocides having mercury as an active incredient are favorable for the environment, of course. But the microbial growth inside the paper machines has activated at the same time.
The beginning of neutral paper production led to an "ecocatastrophe" inside paper machines. The rise of pH value (as well as the rise of temperature, caused by the extended recirculation of water) was fatal for slow, acid-loving fungal growth. New mineral additives are an important source of certain types of bacteria, causing severe problems like production of slime, spoiling of the process compounds and hygiene faults of the products.
IM has published an article "Paper Machine: an Ecosystem and a Bioreactor" (INOCULA 1/2007. Helsinki, Finland). Many readers agree: paper machines offer ecological niches for bacteria, and the controlled environments of wet end circulations are very much similar with those of biotechnical processes, based on chemostatic fermentors.
A lot could be do to make paper machines more unfavorable growth environment for microbial contaminants. Very good results have been achieved in some projects where ecological aspects have been taken into account. These issues will be discussed later in this blog.
But the main question is: how much biocides we still need to control the microbial growth in all regions of a paper machine?
Incoming raw materials, sorry to say, may be very contaminated: the highest value of total count during IM's career has been over 100 000 000 cfu/g in a mineral slurry (which was fortunately replaced by a fresh lot by the supplier!). It is therefore obvious that a continuous control - both analytical and practical - is needed for starches, mineral pigments and other contaminated raw materials. This does not mean that all lots are spoiled: there are suppliers which know their response to deliver pure products to the mills but all kind of errors in biocidic pre-treatment, transport and storage of these products may happen.
Certain sites of paper machines also need biocidic treatments all the time. Chosing proper solutions for biocide programs (type of biocide, active compound, dosing sites, timing etc.) of a paper machine is a challenging tasks. In best cases, both the paper mill and biocide personnel are sitting down and discussing of the individual problems of the paper process hygiene.
When specified laboratory services, having tools like PMEU and biofilm microscopy, are included, the final result can be optimal one. Paper industry microbiologists can also help significantly by declaring the effects of process parameters on the growth of planktonic and biofilm bacteria.
The more competence is included, the better solution will be find.
Tuesday, August 19, 2008
An ideal biocide - is there any?
What should an ideal biocide be like?
* effective against a variety of microbial species
* effective in different process environments (temperature, pH, RO potential, solid concentrations etc.)
* both fast and conserving type of action
* not harmful for employers of paper machine
* not harmful for paper machine
* not harmful for products of the paper machine
* not harmful for environment
* (something else?)
As far as IM knows, no such ideal biocide has been developed yet. "Tailored" biocide products shall therefore be combined to fight against raw material contamination, microbial activity in large process water and pulp systems, fiofilm producers...
The rapid development of fast-acting oxidative agents (chlorine-and bromine-based compounds, PAA, ClO2 and even O3) is very promising, but they have relatively limited success as storing agents. Their broad-spectrum influence on even bacterial spores should be taken into account
when planning biocide programs, which also should contain compounds to prevent biodegradation during storage periods and formation of biofilms on wet surfaces of the machine.
In some cases, activity of alternative biocides against certain hazardous bacteria are also worth to evaluate.
* effective against a variety of microbial species
* effective in different process environments (temperature, pH, RO potential, solid concentrations etc.)
* both fast and conserving type of action
* not harmful for employers of paper machine
* not harmful for paper machine
* not harmful for products of the paper machine
* not harmful for environment
* (something else?)
As far as IM knows, no such ideal biocide has been developed yet. "Tailored" biocide products shall therefore be combined to fight against raw material contamination, microbial activity in large process water and pulp systems, fiofilm producers...
The rapid development of fast-acting oxidative agents (chlorine-and bromine-based compounds, PAA, ClO2 and even O3) is very promising, but they have relatively limited success as storing agents. Their broad-spectrum influence on even bacterial spores should be taken into account
when planning biocide programs, which also should contain compounds to prevent biodegradation during storage periods and formation of biofilms on wet surfaces of the machine.
In some cases, activity of alternative biocides against certain hazardous bacteria are also worth to evaluate.
Wednesday, August 13, 2008
Shared responsibility for paper machine hygiene.
Current situation of process hygiene control in paper industry is relatively complicated.
No matter very effective control methods are already available (epifluorescence microscopy, ATP Assay, PCR, PMEU incubations) the roles of paper mills, biocide suppliers and raw material producers are not very clear.
Based on the experiences by Industrial Microbiologist since beginning of 80', it seems that paper mills prefer external services and this tendency is evergrowing today. Biocide suppliers have developed novel analyse methods which can be applied even at the mills, and many raw material suppliers know their response to deliver minerals, starches etc. with good hygienic quality for paper and board mills.
What should still be developed is the active role of paper mills themselves to control their machines. There is no more any need for expensive microbiological laboratories - in opposite, many methods could either be applied by wet end laboratories of the mills or be bought from external companies (ref. BIOTOUCH Service).
Wet end chemistry has already been controlled with ON LINE analyse units by certain institutes in Finland over years. ON LINE microbiological control is also coming soon, referring several current project proposals.
A combination of all parties - paper mills, biocide suppliers and raw material producers - would spare remarkable amount of money by optimizing biocide programs, by planning washing programs, by responsing immediately to hazardous situations and avoiding costs of returned products.
No matter very effective control methods are already available (epifluorescence microscopy, ATP Assay, PCR, PMEU incubations) the roles of paper mills, biocide suppliers and raw material producers are not very clear.
Based on the experiences by Industrial Microbiologist since beginning of 80', it seems that paper mills prefer external services and this tendency is evergrowing today. Biocide suppliers have developed novel analyse methods which can be applied even at the mills, and many raw material suppliers know their response to deliver minerals, starches etc. with good hygienic quality for paper and board mills.
What should still be developed is the active role of paper mills themselves to control their machines. There is no more any need for expensive microbiological laboratories - in opposite, many methods could either be applied by wet end laboratories of the mills or be bought from external companies (ref. BIOTOUCH Service).
Wet end chemistry has already been controlled with ON LINE analyse units by certain institutes in Finland over years. ON LINE microbiological control is also coming soon, referring several current project proposals.
A combination of all parties - paper mills, biocide suppliers and raw material producers - would spare remarkable amount of money by optimizing biocide programs, by planning washing programs, by responsing immediately to hazardous situations and avoiding costs of returned products.
Saturday, August 2, 2008
Evaluation of slimicides for paper machine process waters.
Time series of steel coupons are the common method to evaluate the effects of biocides against slime-forming bacteria in paper machine processes.The installation of coupons inside the machine may not be the main problem. Two other aspects will limit the value of this method:* only one slimicide (= the current slimicide used in the machine) can be tested
* duration of the evaluation may take days...weeks
PMEU Incubator (by FINNOFLAG Oy) has been adopted into biocide and slimicide testing because it gives chance to
* evaluate several biocides/slimicides at the same time
* only hours to days are needed to have the results of evaluations
Picture (above) shows a bacterial population, attached on the surface of a PMEU test coupon, with fibres, minerals and starches. These bacteria stand washing of coupon with water after testing which means that they are "primary attachers" on the surface of steel when immersed in process water of a paper machine.
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