Process conditions in paper manufacture
favour the growth of microbial contamination, causing production-disrupting
slime formation in the machines. This situation is further aggravated
by the trend towards more environment-friendly closed-loop water systems
and the maximised incorporation of recycled fibre as a raw material. The
European Commission funded SLIMEZYMES project will research the use of
new enzymes as full or partial replacements for the biocides currently
Slime control is necessary in paper and board production
to ensure high quality and trouble-free operation, without downtime caused
by slime-induced paper breaks and fouling of paper machinery. At the same
time, paper manufacturers are demanding more of their microbial control
programmes, in order to meet higher quality criteria from customers, face
hard competition in the marketplace and comply with tougher environmental
The SLIMEZYMES FP5 Growth project was set up to find a clean and sustainable
alternative to existing materials. The four-year project brings together
a multinational consortium led by VTT
Biotechnology of Finland and including a mix of universities, research
centres and industrial companies. Among the members are Novozymes
, a world leader in enzyme business and biotechnology development, prominent
slime control agents supplier Buckman
Laboratories and paper-maker Papalera del Jarana.
on the surfaces of paper machines form slime biofilms consisting
of microbial populations embedded within a self-produced matrix
containing extracellular polysaccharides. The objective of SLIMEZYMES
is to employ modern biotechnical methods to develop novel targeted
enzymatic approaches for efficient degradation of slime polysaccharides,
bringing enhanced productivity, improved final product quality and
The use of enzymes will be studied alone, in combinations, and in
synergy with other control agents such as dispersants and biocides.
Enzymes capable of degrading slime polysaccharides will be identified
and isolated from micro-organisms collected from soil, compost and
various paper mills. Others will be isolated using modern DNA microarray
technology. Those showing the greatest promise will then be screened
for their ability to degrade slimes isolated from a range of paper
Potential candidates will be produced on a pilot scale for further
laboratory evaluations and application experiments. Parameters giving
best slime degradation in circulation water systems will also be
identified, and these optimised methods verified under real paper-machine
Industrial experiments will first be conducted in a side-stream
loop, and later at full mill scale. In addition, the effects on
operating parameters of progressive water system closure will be
investigated, as well as the influence on subsequent effluent treatment.
and economic advantages
A positive outcome
will bring important benefits for the pulp and paper industry, which
is a significant economic sector in Europe. Seven of the world's
top 20 companies are located in the EU, and there are around 1300
EU paper mills.
Enzymes represent a clean and sustainable technology: they are non-toxic,
readily biodegradable and produced using renewable raw materials.
The new methodology will contribute to efforts to reduce water consumption
and facilitate the use of recycled fibre.
Arising from the results will be the potential to manufacture and
market new 'green' slime control products. Industry will gain the
advantage of more eco-efficient processes, which will also have
impact on consumers as a whole - especially with respect to the
elimination of undesirable substances in food packaging materials.
In accordance with the Growth programme's
products, processes and organisation key action, SLIMEZYMES
seeks to eliminate the slime formation that often creates problems
for paper mills attempting to run closed loop water systems.
- Eco efficient novel enzymatic concepts for slime control in
pulp and paper processing (G1RD-2000-00387)