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Targeting microbes on paper machines

FennoClean is Kemira's new all-in-one concept for combating biofilm and keeping microbial contaminants in papermaking processes to a minimum.

The FennoClean concept has been designed to enable chemical usage to be tailored to application needs more efficiently, and achieve low levels of process contamination more cost-effectively. A clean process means better end-product quality and better productivity.

Understanding what is really going in biofilm formation is important for better overall papermaking performance, believes Kemira. Innovative research has resulted in a new, all-in-one concept for combating the problem: FennoClean.

FennoClean is based on extensive in-house biofilm research, the results of which have created the foundation for a series of new approaches to combating biofilm formation. These solutions reduce process contamination and enhance the efficiency of paper and board machines to a significant degree – as the microbial slime that forms on machine surfaces contaminates process water, can halt production, and reduce the quality of a mill's end-product.

Getting to the bottom of the problem

Traditionally, the level of microbial contaminants in a process, together with the efficacy of a microbe management programme, have been monitored by determining the quantity of free-swimming bacteria in samples. The dosage of the chemicals used to control these microbes has been based on the same data.

This type of monitoring does not necessarily tell the whole story about a process, however, either in terms of overall microbial contamination or the speed at which biofilm forms.

In some cases, you can succeed in reducing the numbers of free-swimming bacteria dramatically, using what appears to be the 'right' biocide according to conventional wisdom, but see the amount of problem biofilm increase dramatically.

Thanks to Kemira's new test methods, it is now possible to understand why this happens.

Targeting the colonizers

Kemira's research work – carried out in collaboration with the University of Helsinki and leading paper manufacturers – has shown that so-called colonizer or precursor bacteria play a key role in biofilm formation. These precursor bacteria are able to attach themselves to bare metal surfaces very easily, and rapidly attract other bacteria to these sites, which then become diverse microbial communities.

Based on this insight, Kemira has turned its attention to combating precisely these colonizer bacteria. The result has been that it is now much easier to prevent biofilm from forming in the first place, and keep processes uncontaminated by using significantly smaller quantities of chemicals.

Colonizer bacteria adhere to bare metal surfaces and attract other bacteria, resulting in biofilm formation. One example of a primary colonizer, Deinococcus geothermalis, can be seen here.

Kemira is the only company to offer tools for identifying colonizer bacteria and targeted tools for combating them; and has also developed a DNA-based method for determining whether problems in the paper that comes off a line are the result of microbial contamination.

The FennoClean concept is not just about combating slime with more targeted biofilm control chemicals, however. Better use of washing chemicals, water treatment, overall bacterial management, and additive storage are also key factors.

Together, they contribute to better process hygiene and cleaner products, a major plus in areas such as packaging board used by food manufacturers.

The cost factor is also significant. If a machine has to be stopped 24 times a year for eight-hour cleans to remove biofilm deposits, this translates into nearly 200 hours of downtime annually. Extending the intervals between cleaning cycles by a week can reduce this to less than 130 hours a year, improving a mill's overall cost efficiency considerably.

Even more important in the future

More efficient slime control and more contaminant-free processes will be even more important in the future, because of the shift towards closed processes and reducing water usage and tougher statutory regulations.

Mills are already using 6-10 cubic metres of water per tonne of paper produced, and the trend is to cut this even further.

Tougher statutory regulations on chemical usage, for their part, will see mills having to operate with smaller amounts of chemicals than they do today, and it is also probable that the use of some active ingredients will be limited, which will also make combating microbes more difficult.

When mills can focus their chemical use very precisely, as they can with the Fenno­Clean concept, they will get better cost efficiency with lower levels of chemical usage long term.

A better system

  • Efficient process cleaning
  • Targeted biofilm control in short and long circulation
  • Total bacterial management of broke
  • Enhanced additive longevity
  • Raw water treatment
  • Contaminant-free end-product
> Juha Rintala
(Published in High Technology Finland )