Finland's four-year programme aimed at finding ways to reduce the amount of water required during papermaking has just been completed. It has led to new findings on the inter-dependency of water consumption with the entire papermaking process and shown that future developments must also bear in mind factors such as the formation of solid wastes.

The aim of the CACTUS technology programme, which was funded by the Technology Development Centre (Tekes) and major companies of the forest cluster and co-ordinated by VTT, the Technical Research Centre of Finland, was to reduce the consumption of water in the papermaking process.
The performance of new water treatment methods as well as their integration into the process and their overall effect were studied. The four-year programme, which cost FIM 100 million and involved the combined efforts of chemists, physicists, papermaking engineers and energy sector experts, produced new knowledge on the complex dependent relationships of water consumption in the paper manufacturing process.
A calculation system encompassing the entire paper mill was developed in order to study the environmental effects of process changes designed to reduce water consumption. This calculation system has been taken into use both in the industry and in universities.
The Finnish forest industry has reduced its total effluent load to approximately one twentieth of the level prevailing in the early 1970s. Cutting environmental impacts has required the development and introduction of new technologies and production methods.
According to statistics of the Finnish Forest Industries Federation, about FIM 8 billion has been invested in environmental protection since 1985. Even though the results achieved so far are good even by international standards, efforts aimed at reducing environmental impacts on the soil, air and water must be continued.

Reducing consumption

In accordance with the forest industry's longer-term goals in environmental protection, all kinds of efficiency improvements are being sought in the use of both raw materials and other production inputs. Reducing the consumption of water and energy is important when improving environmental protection.
Working within the framework of the CACTUS programme, forest cluster companies together with Tekes and VTT have developed expertise by which the consumption of water can be reduced in paper manufacture. The measurement of circulation water quality and control of the process's chemical phenomena were studied and simulation tools developed in the programme.

A dedicated simulation environment was developed in order to create a database in which knowledge generated in the research programme could be recorded, thereby allowing easy exploitation by the parties involved in the technology. The development of simulation expertise was also seen as strengthening Finland's position as a pioneer in the development of papermaking and paper machine technologies. The aim was to find solutions that would safeguard the efficient manufacture of high-quality wood-containing papers, which is the cornerstone of the Finnish paper industry's competitiveness.
The knowledge gained from the programme has shed much light on the dependent relationships of water consumption, raised the level of the companies' own expertise, and helped to outline problems associated with closing the water circulation system and the entire process.
At the outset of the programme it was seen that essentially reducing water usage adversely affects the process water quality unless the water is treated separately. It was also found that it is important to find comprehensively rational ways of utilising the substances removed in internal water treatment. Indeed, a key aim of the research was to make a comprehensive study of paper manufacturing from the perspective of sustainable development.
Future process concepts cannot be built solely on the basis of reducing the effluent load; the formation of solid wastes as well as energy consumption and costs must also be taken into consideration. Now these issues can be examined more systematically using the BALAS simulation software developed by VTT Energy.

BALAS makes its mark

The forest cluster companies involved in implementing the CACTUS programme (UPM-Kymmene, Stora Enso, Metsa-Serla, Myllykoski, Metso, Andritz-Ahlstrom, Hadwaco, Kemira Chemicals and Raisio Chemicals) as well as the universities and some design offices are now expanding the use of simulation software in process and plant development, in mill design, and in the use of chemicals in design and teaching. This is taking them into a new era in the development and optimisation of environmental processes.
The BALAS software application has already been used in the design of a new cooling water system for Stora Enso's Kotka mills, in the modernisation of the power plant at UPM-Kymmene's Jamsankoski mills, and in the calculation of initial values for an environmental permit application by Metsa-Serla's Tako mills. The software has proven itself to be applicable to the design of a wide range of mill-related investments. Greater precision in design and the analysis of a wide range of alternative solutions can shave tens of millions of Finnish marks of the total investment cost.
The results of the CACTUS programme have also contributed to improving the prerequisites necessary to boost exports of water-conserving equipment and processes to countries where, unlike in Finland, water is a scarce resource.