Cleaner Technology Projects in Denmark 1996
Increased Recycling of Water in the Paper Industry
Øget genbrug af vand i papirindustrien
Arbejdsrapport nr. 68, 1996, Miljøstyrelsen
The paper mills are among the industries with the largest water consumption, and therefore many plants have started to recycle the water, which can cause problems with the work environment and obnoxious smells. The purpose of the project has been to develop a technology to control the microbial growth in re-circulated water used in the paper- and cardboard making industries, and in that way, to solve the problems in the work environment and the bad smells caused by recycling of the water and if possible to achieve completely closed systems.
The project has been carried out in co-operation with Brdr. Hartmann A/S, IPU (Institute for Product Development) and VKI (The Water Quality Institute).
In chapter 2 the production of cast cardboard at Brdr. Hartmann A/S is described. In short terms it consists of three steps:
 | Dissolution of recycled newspapers |
| Steeping of the product in paper-making machines |
| Drying of the product |
In chapter 3 the water system is described with the ordinary water consumption in the production as opposed to the optimal water consumption by using the measures introduced today. Thereby it will be possible to see how a targeted effort will be able to reduce the ordinary water consumption remarkably.
Chapter 4 describes the mechanisms used for a reduction of the microbiological activity in the water- and production systems at Brdr. Hartmann’s. Different tests are described e.g. tests with biofiltration and membrane filtration, and an account of the different results and conclusions regarding this is given in the chapter.
Chapter 5 describes three possible scenarios for increased recycling of water. They are expected to result in a controllable biological growth with the possibility of reducing the use of biocides and water.
In chapter 6 an environmental valuation of the contents in wastepaper and the used raw materials and chemicals are made. Furthermore, a statement has been made for the mass-streams for the contents in waste paper and chemicals, which however is mostly based on estimations.
In chapter 7 the three scenarios are environmentally valued in accordance with the LCA-method. Thereby it appears that it is a reduction of the usage of biocide alone, which can defend further water purification and recycling at Brdr. Hartmann’s. In return it will be beneficial to introduce water-purifying technologies, which will be able to reduce the use of biocides.
Chapter 8 concludes that biofiltration is a suitable technology to control the microbial growth in the re-circulated water used in the paper- and cardboard making industry and that ultrafiltration of the re-circulated water produces water of a high quality. Furthermore, it can be concluded that any reduction in the use of biocides will, all in all, lead to an improvement of the environment. To document the reductions in the use of biocides it is recommended to test the upgrading techniques used in a production-like scale. Apart from this, other suggestions are made for the use of the various filters.
Author/ institution
Sven-Erik Jepsen, Vandkvalitetsinstituttet
Hans Henrik Knudsen, Instituttet for Produktudvikling
This report is subsidised by the National Council for Recycling and Cleaner Technology
ISSN no. 0908-9195
ISBN no. 87-7810-693-1