notes on Biotechnology for solving slime problems in the pulp

1. BIOTECHNOLOGY FOR SOLVING
SLIME PROBLEMS IN THE PULP
AND PAPER INDUSTRY
KAVYA G
18LS301010
MSc BIOTECHNOLOGY

2. INTRODUCTION
• A well-known and long-standing problem in paper manufacture is the
proliferation of biological slimes on machinery.
• And these biofilm build-up is characterized by an increased resistance to
biocides, by the development of anaerobic zones, by structural heterogeneity, and
by protection from predative grazing micro-organisms and from desiccation.
• Virtually every surface examined in natural, industrial, and pathogenic
ecosystems is colonized by biofilms consisting of adherent (sessile) bacterial
populations enmeshed within a glycocalyx matrix.
• Some of the biofilm is made up of glycocalyx and microbial extracellular
polysaccharides

3. • Although biofilm formation has been studied extensively in natural
aquatic systems, waste water treatment systems, and medical appliances ,
only a few studies have been made on biofilms in the paper machine
environment.
• Recent work by Vaisanen et al. has shown that paper machine biofilm has
a complicated biological and chemical structure, which morphologically
resembles those of waste water biofilms, biofilms in industrial cooling
towers, and natural river ecosystems.

4. SLIME CONTROL
BIOCIDES:
• Using of these biocides became a part of the paper and pulp industry.
• Properties : cheap, efficient , and should not disturb the papermaking
process.
• Chemical companies started producing these slimicides like oxidizing
slimicides, non oxidizing slimicides. And in recent years the registration
has become difficult because they emphasized on characteristics like
handling slimicides, health and safety issues, and fate in the environment.

5. Cleaning:
• To control the slime, mechanical cleaning and boil out at extreme pH
levels and high temperatures.
• Cleaning is often done with high pressure water flushing and flushing of
the system with lye and tensides.
• Mechanical cleaning and boil-out are often impracticable, and can be
costly because they usually involve equipment down time.

6. How BIOTECHNOLOGY is solve this problem
Biosufactants
• The term biosurfactant has generally been used very loosely to refer to any
compound which has some influence on interfaces.
• For example, it is often applied to biopolymers which have emulsifying
properties but do not lower the surface tension of water appreciably or
demonstrate other characteristics of a classical surfactant.
• Microbiologically derived surfactants (biosurfactants) are more conveniently
discussed in terms of the biochemical nature of the surfactant, e.g. protein,
polysaccharide, lipid, or a complex containing two or more types of biomolecule,
and the producing microbial species .

7. • Surfactin, produced by Bacillus subtilis ATTC 21332 is one of the most effective
biosurfactants known.
• Polysaccharides occur as microbial energy reserves and as structural material in cell walls
and extracellular capsular layers.
• A large number of extracellular polymers have gained commercial importance due to
their ability to alter, at low concentrations, the rheological properties of aqueous
solutions. Such polysaccharidic hydrocolloids are used in the food, pharmaceutical,
cosmetic, oil, paper and textile industries as thickening agents and viscosity modifiers.
• The best characterized lipopeptide surfactants are surfactin, which has been isolated from
several strains of Bacillus subtilis and Bacillus pumilis, viscosin, produced by
Pseudomonasfluorescens , and arthrofactin, produced by Arthrobacter sp. strain MIS38 .

9. • Biosurfactants are involved in cell adhesion, emulsification, dispersion,
ftocculation, cell aggregation, and desorption phenomena.
• Acinetobacter calcoaceticus RAG-l, whose ability to degrade and disperse crude
oil due to the emulsification of the oil by an extracellular polyanionic
amphipathic heteropolysaccharide, emulsan, has been used in low concentrations
to inhibit the adhesion of bacteria to hydrophobic surfaces.
• Biosurfactants are biodegradable, potentially less toxic than the synthetic
compounds currently used, and can be produced from a variety of substrates.

10. ENZYMATIC SLIME DEPOSIT CONTROL
• Today's research is focused on both the prevention and the disruption of biofilm
build-up caused by slime-forming species of bacteria, yeasts and fungi. Many of
the approaches include the use of enzymes.
• Certain kinds of polysaccharide substances can be removed from the cells by
treatment with specific hydrolytic enzymes. Such enzymatic treatment leaves the
cells unharmed .
• The stripping of the extracellular polysaccharide layer prevents the cells from
attaching to other surfaces and makes them more accessible to conventional
biocide treatment.

11. • The use of enzymes in the control of microbiological slime deposits, particular EDC-1 (enzymatic
deposit control) developed by Hatcher has proved useful under modern mill conditions.
• EDC-1 is an enzyme that hydrolyses and depolymerizes the fructose polysaccharide levan, which
has been identified in paper mill slime.
• EDC-1 is a patented enzyme product obtained by aerobic fermentation of a common non-
pathogenic, non-spore forming soil bacterium, which has been tailored to suit the specific needs of
the paper industry.
• It is non-toxic, does not promote resistance, does not accumulate in the system as it is inactivated at
80-100⁰C and is safe to handle. The product can be dosed solely or in conjunction with
conventional biocides.
• Simultaneous application of EDC-1 and biocide allows the amount of the latter to be reduced.

12. • It has been pointed out that it is in practice not always possible to achieve
satisfactory slime control by dosing EDC-1 solely to the process waters.
• The reason is that EDC-1 is a specific levan - hydrolyzing enzyme, i.e., it
is restricted to levan-producing bacteria, which have been shown to be a
secondary factor in many process waters.
• The bacterial number may increase during enzymatic treatment of the
extracellular polysaccharides, since the carbohydrates released serve as
food for the bacteria.

13. • Despite the strong indications that exo-polysaccharides are involved in
adhesion, enzyme digestion has tended to show that proteases are more
effective than carbohydrate-degrading enzymes in removing bacteria from
surfaces.
• Rhodozyme HP-150 is an enzyme which is used for the control of slimes
in industrial effluent.
• The use of a blend of enzymes has been shown to be more effective in
treating the slime.

14. BIODISPERSANTS
• Biodispersants play an essential role in modern treatment programmes to control
biofilms caused by excessive growth of micro-organisms such as bacteria, yeast,
and moulds.
• Biodispersant technology is based on non-ionic polymers, which are nontoxic,
non-foaming, colourless, and free of organic solvents. Because of their non-ionic
character, they will neither increase the system anionicity nor interfere with other
papermaking chemicals
• Biodispersants have no pH limitations and are suitable for use in both acid and
alkaline papermaking

15. • The use of biodispersants is recommended in cases where the amount of biocides
has to be reduced, the efficacy of the biocide has to be increased, or the biocides
have to be totally replaced.
• Because biodispersants can neither kill micro-organisms nor inhibit their growth,
the use of biocides may still be needed, even in cases where the ultimate goal is
to avoid the addition of biocides altogether.
• However, the use of biodispersants can enhance biocide effectiveness by
eliminating biofilm, inorganics, and organics which can inhibit penetration of the
biocide into the organism.