Problems due to micro-organisms

Defects in paper sheet. The biofilm or thin slime deposit can further increase in size as it entraps the wood fibers, carbonates, clays and other particles normally used in the papermaking process. 

At times, a sticky or polymeric matrix may be present. The possible origins of the sticky materials may include the production of exo-polymeric materials by bacteria, pitch, or even upsets in the chemistry of the paper-machines that would result in, for example, gelled alum. 

The biofilms in papermachines form massive slime deposits that can be an inch or more in thickness. When these deposits break loose and fall into the paper furnish, they result in end product defects such as holes and spots or even paper sheet breaks. When this occurs, the paper with the defects must be used as broke and re-pulped or downgraded. If the paper containing these holes makes its way to a new high-speed coater, massive problems may result. 

If microbial deposition is not controlled not only can it interfere with runnability, but it can also slough from surfaces leading to spots and/or holes in the finished sheet. 

Surface deposits and sloughing also serves as an additional source of contamination therefore, control is critical to the cleanliness of the system. 

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