Slime control in paper mill using biological agents as biocides

The environmental conditions of paper mills are suitable for the growth of slime-forming microorganisms due to the supply of nutrients, favorable temperature, and moisture. The slime formation causes the spoilage of raw materials & additives, breaks in the paper during papermaking, loss of production, reduces the hygienic quality of the end products, produces off-spec and rejected products, creates microbiological corrosion, and produces harmful gases. The main microorganisms are Bacteria (mainly Bacillus spp., Achromobacter spp., Enterobacter spp., Pseudomonas spp., Clostridium, etc.), Fungi (Aspergillus, Penicillium, Saccharomyces, etc.), and Algae. Besides the use of conventional toxic chemical biocides or slimicides, slime formation can also be controlled in an eco-friendly way using enzymes, bacteriophages, biodispersants, and biocontrol agents alone or along with biocides to remove the slime. Enzymes have shown their effectiveness over conventional chemicals due to nontoxic and biodegradable nature to provide clean and sustainable technology. Globally enzymes are being used at some of the paper mills and many enzymatic products are presently being prepared and under the trail at laboratory scale. The specificity of enzymes to degrade a specific substrate is the main drawback of controlling the mixed population of microorganisms present in slime. The enzyme has the potential to provide the chemical biocide-free solution as a useful alternative in the future with the development of new technologies. Microorganisms control in the paper mill may appear as a costly offer but the cost of uncontrolled microbial growth can be much higher leading to slime production and large economic drain.