Environmentally-accepted biocides

Add a Comment

28 Comments

Comment by Juha Veikko Mentu on August 8, 2009 at 9:15pm

Sulphate Reducing Bacteria in paper industry.
SRB is an interesting group of bacteria which can use sulphate as an electron acceptor for the respiration. Despite the chances of certain other bacteria to use sulphate as the sulphur source for their S-containing cell components, the "real" sulphate reducers transform SO4(2-) to S(-2) in their energy metabolism and oxygen actually inhibits their growth - they are therefore obligate anaerobes. Certain yield of energy may be achieved through fermentation by SRB's but this type of metabolism is regarded as relatively insignificant one for them.

These bacteria have first detected in waste waters of sulphite pulp mills but modern paper machine processes can also induce their growth if certain sulphur-containing compounds are available.

In addition to H2S production (which is a hazardous gas), colour problems can arise because the metal sulphides. FeS is an indicator compound in the analytical detection of SRB's but also a harmful agent of discolorization of paper and paperboard. Last but not least, SRB's have been shown to be conneceted to a certain type of iron corrosion and it is all possible to find those problems still today whenever technical structures with poor steel quality and certain types of organic deposits on their surfaces are combined.

SRB's have also other, peculiar features like the tendency to follow non-exponential growth curve. They have been the subject of firm microbiological research only since the middle of 20th century because their need of anaerobiosis was not understood earlier.

Suphate Reducing Bacteria are also a challenge for the biocide comapnies, serving the paper industry. Oxidative agents like ClO2 and PAA can be the right alternatives because they will rise the redox potential of the waters and prevent the growth of anaerobic SRB's. There are still severe questions about the penetration of biocides into deposits which cover the SRB.

FINNOFLAG Ltd. is currently developing a novel method for the sensitive detection of SRB's with PMEU method - more about this topic in next posts.

Comment by Juha Veikko Mentu on July 24, 2009 at 5:47pm

IM (my alter ego) has discussed about alternative methods for the detection of hazardous or harmful bacteria with Dr. Elias Hakalehto.

It is most important to know the pathogens which will appear in patient samples. Clinical microbiologists shall know who are the enemies of the ill people: their metabolic capabilities, antibiotic resistence patterns etc. Their overall features are easy to find from literature or internet whenever the name of the species is known. This identification can be performed by selective cultivations on agar plates or in PMEU incubator, and further tests like microscopic examinations, API ID systems, immunological tests and/or PCR can be done to confirm the basic identification.

Paper mill is definitely another challenge for microbiologist. In some (relatively rare cases) the names of microorganisms are important to know: if the product shall have high hygiene quality (like LPB and other food-grade cartonboards) or questions about bioterrorism have been arisen (spore-forming Bacillus anthracis as an example). The occurrence of Legionella pneumophila is also a risk in the waste water treatment of paper industry today. Selective cultivations, either on plates or in PMEU, are the solid solutions for continuous microbiological control in those cases. PMEU is preferred because its speed (hours, compared to days with colony count analyses).

Papermakers shall focus more on the metabolic activities than the names of bacteria which they are living with in paper mills, however. Continuous inoculation of the paper production processes by contaminants, delivered with incoming lots of starches, mineral fillers, raw water, dry pulp etc. shall be controlled to avoid spoilage (amylolytic activity as an example), biofilm and slime growth, tastes and odours, spots and colours in the product etc. Because the wide range of bacterial species and their origin from the nature itself, clinical methods do not suit very well for this monitoring. There is no time to start labourous cultivations, pure cultures and identifications when the bacterial input continues day and night, "7/24". PMEU seems to be an excellent tool to check the basic features of process populations, their biocide resistence patterns included.

One important fact must also be taken into account. There are a lot of harmful microbes which actually cannot be cultivated on agar at all. One example are certain filamentous bacteria which may cause biofilm layers into the processes. They can be cultivated in some broths, however, but the usage of the original samples as the growth medium is the best way to detect them all. This can be done with ordinary mb laboratory equipment or with PMEU incubator.

Identification of bacterial species is still needed when the mapping of contamination routes into the processes is the subject of the study. IM will discuss about the microbiological mapping in his next posts (please see http://industrymicrobiologist.blogspot.com/).

Comment by Juha Veikko Mentu on June 8, 2009 at 2:06pm

Latest post by IM, dated 7.6.2009:

Certain types of microbiological problems in paper mills seem to be acute all the time. Looking back to last months, this may be "Top Three" among them:

* Microbiological spoilage of raw materials. This is an everlasting hazard for mineral and starch slurries, and the reasons are very easy to understand: both raw materials mentioned may contain high densities of bacteria (mainly aerobic sporeformers and actinobacteria), slurries containing starch are very nutritive growth media for different microbial species and the very challenging biocidic treatments of slurries (especially mineral ones), when inaccurate, can lead to the total spoilage of them.

* Growth of biofilm and production of slime. This problem seems to be connected to poor washing and boil-out programs which leave rests of biofilm inside the machine and give growth time for it because too long running periods. The chose of ineffective biocide and/or its insufficient dosing can also stimulate the activity of these trouble-makers.

* Microbial growth in the broke system. Especially big machines with large broke towers suffer of this problem. If the basic biocide program is insufficient and the retention times inside the towers are too long, aerobic population tend to increase the number of its cells to the level of 10 000 000 cfu/g or even higher. Consumption of oxygen by respirating bacteria leads to anaerobic conditions, redox potential will be dropped and the growth conditions for both fermentative and anaerobic bacteria turns to be excellent. Drop of pH, slime and spore formation, smells and odours - even the production of H2S and H2 - will be found in such situations.

There are some measures to prevent these hazards. Growth period of microbial population shall be kept as short as possible, the control of waterborne and bioflim bacteria shall be as rapid and frequent as possible and the bioside programs, intended in killing of raw material, process water and biofilm bacteria shall be evaluated more frequently.

A realistic and accurate way to control both process water and biofilm growth, as well as to evaluate biocide programs, is now available. The Finnish company SAMPLION Ltd is manufacturing and selling "Portable Microbiological Enrichment Unit", a "mini-fermentor" for 10 simultaneous tests in controlled conditions, to detect the failures of biocide programs in only hours (watesr) or days (biofilms). Some results of PMEU's paper industry applications will be published in next Spring - coming back to refer them later.

Some wrong ideas about the overdosing of biocides will also rise up frequently among publicity. Basically it is not a question of only the cubic meters of biocides consumed, however, The chose of most effective biocides for different areas of processes towards different problems, the dosing of these compounds, their type of action and some other factors play a major role when building an effective biocide program for paper machine. Overdosing of biocides is a problem only in cases, when the program does not work, and leads to the loss of money and the rise of biocide concentration in paper machine effluents.

Comment by Juha Veikko Mentu on March 17, 2009 at 8:26pm

IM is wondering, what will the future of P&P be like.

Referring his ideas, five major topics are needed:

1 PRODUCT: you shall have some product which is really needed among customers. An example: LPB (everybody will buy milk and juice in carton packages every day during her/his lifetime).

2 PERSONNEL: persons on all levels of the company, interested to sell good products.

3 MARKET: the only question: are the customers well aware about your product? If not, why?

4 RESEARCH: R&D in P&P is not a region of "sunset". A lot can be done to improve the quality of products, production etc. It would be possible to find even new products: why not to sell motor oil in LPB containers?

5 DEVELOPMENT. This is the most difficult issue. R&D is interested to develop new ideas but the economists do not see any forecasts for the innovations - why?

- O.K. IM is just a microbiologist and do not understand the global economy. He is still asking, however: where is the development and optimistic forecasts in P&P industry?

IM will also ask: are the Asian people more enthusiastic to develop P&P industry? Not only economically but also in their minds?

POSTED BY JUHA V. MENTU AT 11:01 AM 0 COMMENTS
LABELS: CHINA GLOBAL, DEVELOPMENT, MARKET, PERSONNEL, PRODUCT, RESEARCH

Comment by Juha Veikko Mentu on February 9, 2009 at 10:52am

I will refer the excellent book "The Biotech Investor" by Tom Abate (Owl Books, 2003, New York) again. I try to reserve my time to read it through, no matter it is a dense collection of biotech and marketing facts.

In the preface of this book Tom Abate says:

"Biotechnology is an experimental field. Only a handful of of biotech companies currently have products on the market. The vast majority of biotech firms run at a loss during long developmental cycles aimed at proving their founding thesis. Experiments take time, and they often fail. Even when experiments have been done, and their results analyzed and presented at scientific meetings, biotech medicines undergo an excruciating process of regulatory review the can lead to approval, rejection or demands for more testing...In biotech time, development horizons strech for years, even decades."

This is familiar for every modern biotech researchers. Dr. Abate refers medicine research but relatively similar problems may arise when a novel microbiological analyse method is the subject of the research. Approval is then depending not on the health of the customers but the potential markets (my opinion). I still think that such a development task can be fulfilled in only years, but marketing may be a challenging task, indeed.

Comment by Juha Veikko Mentu on February 4, 2009 at 9:03pm

Helge, ideasi PPI-julkaisuun kirjoittamisesta on houkutteleva. Tapahtuuhan näinä päivinä todella paljon P&P-sektorilla! Ja uusia tietoja ilmaantuu päivittäin, uusimpana KCL:n ja VTT:n yhtyminen.

Uutinen oli sinänsä odottamaton, mutta pienen pohdiskelun jälkeen ymmärrettävä. Säästöä syntyy paityisi konttoripuolella, myös tutkimusten päällekkäisyyttä karsien.

Insiderina sain seurata kymmenen vuoden ajan "kolmen koplan" eli VTT:n, KCL:n ja HY/Viikin mikrobiologian yhteistyötä. Nyt olisi jännittävää tarkkailla tilannetta outsiderina varsinkaan, kun oma mielipide ei enää ole sidottu.

"Käärikäämme henkiset hihamme" ja ryhtykäämme töihin!

Comment by Juha Veikko Mentu on January 28, 2009 at 1:00pm

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.

Comment by Elias Hakalehto on January 27, 2009 at 10:34am

Hei, Juha!
Thank you for the imaginative dream regarding the paper industry HACCP and BIOTOUCH. It is definately required to miniatyrize our thinking onto the size and level of the bacteria and microbes in general. - For the follow up of these microbes we should get new sites for experimentation with the PMEU (Portable Microbe Enrichment Unit) (Finnoflag Oy) within the paper and pulp industries. It is for sure that this approach could provide a competetive edge for any sector of these industries. The enhanced microbiological method could make the hygiene and process control more sensitive, precise and much faster.

Comment by Juha Veikko Mentu on January 26, 2009 at 11:42pm

Imagine yourself as a bacterium.

You are coming to the paper mill - maybe waterborne, maybe as a bug or as a spore in a lot of starch or mineral pigment.

What will happen to you?

Do you find an ecological niche inside the machine?

I am sure, you will find.

You will find a wet surface, some of your genes will be activated for the living inside a biofilm.

You have fellow bugs there. You could even communicate chemically.

And, after a period of lush life inside the biofilm, you get older and will be released into the water current.

And you wish, that there are no detectives, controlling your movements inside the paper machine: wet end systems, pulp and broke systems, mineral slurry and starch size routes...

The detectives belong to HACCP. They know where you will hide...

- This is my dream. Tools for this kind of HACCP are already available.

Comment by Juha Veikko Mentu on December 31, 2008 at 10:07pm

There are only a couple of hours left in 2008. I am sitting in the middle of a snow storm in Central Finland, suffering of a flu which I have got as a souvenir from my Latvian visit (Riga is a beautiful city but as cold as Finland during Christmas time).

Looking back to 2008: what has happened on the area of paper industry microbiology?

It seems that certain depression has been obvious in R&D of paper industry - and especially in D. Activities of chemical suppliers will be asked by paper makers to fulfill trouble shooting tasks. Smaller private labs have also been active to assist to solve microbiological problems like H2S production by SRB's, spoilage of raw materials and biofilm formation.

Novel methods - like PCR and PMEU - are on the threshold of applications.

I have only one wish for 2009 regarding paper industry microbiology:

I wish that all partners of the joint activities, intended in securing paper process runnability, will have time and interest to build up cooperation. All elements for this are already available:

* experienced personnel of paper mills
* biocide suppliers, having response to help in mb problems
* novel, rapid analytical tools for P&P microbiology
* private, active research institutes

I therefore wish every one

SUCCESSFUL, COOPERATIVE NEW YEAR 2009!

and promise to myself to be more active as a blog writer for Paper Industry Microbiology!

• 1
• 2
• 3