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Graphic element Research > Growth > Research projects > Cross-disciplinary projects > Enzymes fight paper machine slimes
Graphic element Enzymes fight paper machine slimes

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 employed.

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 legislation.
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.

Targeted approach

Micro-organisms growing 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 greater safety.
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 machine environments.
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 conditions.
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.

Environmental 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.

See also
Community research on pulp and paper

Towards a sustainable future for Europe
Targeted approach
Environmental and economic advantages

Key data

In accordance with the Growth programme's Innovative 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.


SLIMEZYMES - Eco efficient novel enzymatic concepts for slime control in pulp and paper processing (G1RD-2000-00387)

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