What can we learn from the food industry?

Finnish companies (food) keep records on the origin of raw materials, and production series are of reasonable size. This makes it possible to track the history of each product.

The Finnish food industry is small and well organized. Companies keep records on the origin of raw materials. This makes it possible to track history of each product, which is not always an option i mega-sized industries.

Companies like Raisio and Valio have developed food products for people with lactose intolerance, coeliac disease and allergies. Such companies and products are ideal for tracing connections between microbial toxins and raw materials, as well as manufacturing conditions.

Their contract farms could be used to track the effects of harvesting, storage and transport methods.

The Finnish paper industry, meanwhile, makes sophisticated products for specific purposes. Once research advances in food safety risks and the conditions that prevent such developments, purpose-designed food packaging could be designed.

While such targeted planning is crucial, we are going to need broad and sweeping new ideas and working methods.

Politicians, for instance, seek publicity by picking out one single threat instead of searching for broader solutions. This leads to unbalanced threat classification; threats are easily exaggerated or underestimated.

Unfortunately, the future we're interested in is too close to the present, too short-term. Perhaps we don't dare face all the future challenges that are already visible today.

A journey into biocides in Papermaking

Elias and Juha, I've been digging, googling and traveling the world of paper making today. There are a number of reasons why this area needs more PMEU-attention:

1. Closing of papermachine water circulation
   
2. How to find cost-effective ways to handle slime and film formation
3. Biocides are adding the risk for corrosion
4. The felts are degraded
5. Customer complaints are costly
6. Runnability of the paper machine
   
7. Toxic chemicals are used
8. Health issues at paper machine
   
9. The biocide audit requires a talented task-force
10. The problems are global
11. Recycled paper
    
12. Additives
    

Biocides

Biocides: "Mini-Encyclopedia of Papermaking Wet-End Chemistry Additives and Ingredients, their Composition, Functions, Strategies for Use BIOCIDES Composition: There are at least two main classes of biocide.

On the one hand there are oxidizing agents such as chlorine dioxide and hydrogen peroxide.

These happen to be the same chemicals that are also widely used for pulp bleaching. Therefore it is convenient for facilities employing these bleaching agents to add small amounts to the paper machine system as well.

The oxidizing action either kills the bacteria and fungi outright, or it weakens the cell walls so that they are more susceptible to the other main class of biocides.

The other class involves highly toxic organic chemicals.

Subclasses of toxic biocides go by such names as thiazoles, thiocyanates, isothiazolins, cyanobutane, dithiocarbamate, thione, and bromo-compounds.

As the names imply, many of them contain sulfur ('thio'-). A possible third category consists of materials that have an ability to inhibit biological film formation, e.g. surfactants such as alkylsulfosuccinates.

Function: One has to keep in mind that the main goal is to limit the growth of sessile bacteria, i.e. those that are attached to surfaces. These are the bacteria that tend to build up, cause slime deposits and holes, hurt productivity, and hurt product quality.

Strategies for Use: Grades composed of bleached pulps very often involve a combination of treatments with oxidizing biocides, supplemented by toxic organic biocides. The usual recommendation is to treat each of the incoming streams, including the fresh water, filler slurries, chemical additives and makedown streams, etc.

Special attention has to be paid to the starch preparation area, since starch is such a favored food for slime growth. The level of oxidizing agent (e.g. chlorine dioxide) has to be maintained at a sufficiently low level that there are not any problems with bleaching of dyes or decomposition of starch, etc.

A possible starting level to consider is a residual of 1 ppm of active oxidizing agent in the paper machine system. Hydrogen peroxide, when used as a biocide, is slower to act but longer lasting. As a consequence it needs to be controlled at a higher level of residual activity in the system.

The toxic organic biocides can be selected based on the temperature of the system and on the relative needs to control either bacteria or fungal growth.

It is common to cycle the toxic biocide on and off over periods from several minutes to several hours; by this means it is possible to reach a required threshold of activity and also minimize the cost of chemicals.

Such practices of intermittent addition need to be checked to make sure that they do not cause excessive swings in first-pass retention or other problems. Certain biocides are known to contain anionic dispersants that interfere with retention.

The residual level of oxidizing chemicals is most conveniently estimated by measuring the redox potential of the furnish with a Pt electrode relative to a standard reference electrode.

The effectiveness of a biocide program is best evaluated with a combination of measurements, including petri-dish cultures of water, tests for the presence of biological deposits on surfaces, the slipperiness of wetted surfaces, and the level of smells within the facility.

Cautions: Biocides are probably the most toxic materials present in a paper mill and they need to be treated with great respect.

Biocide addition systems should be installed and adjusted only by highly qualified and authorized people.

Anaerobic conditions under deposits can cause release of hydrogen sulfide, which can build up in such locations as tanks.

Never enter a tank until procedures are followed to make sure that the air is safe.