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Graphic element Research > Growth > Research projects > Cross-disciplinary projects > Combined technologies slash paper-mill water waste
Graphic element Combined technologies slash paper-mill water waste
    25-09-2001
 

Confronted with aggressive global competition and tightening environmental legislation, paper mills are being obliged to improve product quality while reducing energy and water consumption, and minimising undesirable emissions. A European Commission funded project enabled a group of European SMEs (small- and medium-sized enterprises) to develop affordable technologies that cut production costs and bring the industry closer to its goal of processing with zero liquid effluent (ZLE).

Without the introduction of new treatment methodology, the build-up of suspended solids, colloidal matter and dissolved contaminants makes it increasingly problematic to raise the levels of process water recycling in paper and board mills. To permit a further closure of the water loop, all such 'accumulants' must either be controlled or eliminated.

Balancing economy and environment
 

In the eighteen-month FP4 CRAFT (co-operative research) project, partners drawn from four European countries pooled their expertise to combine complementary technologies into a chained process offering an optimal balance of production economics and environmental benefit. The consortium was supported under the BRITE-EURAM programme and included paper mills from Germany, Italy and the Netherlands, together with five specialised systems suppliers. The co-ordinator and prime RTD performer was the TNO research institute in the Netherlands with the support of UMIST in the UK. The collaborative effort targeted a 50% reduction in water usage, plus energy savings of 35% and a similar decrease in the volume of chemical inputs. It was envisaged that the application of 'clean' processes would also bring improvements in paper machine runnability, accompanied by an upgrading of the finished product quality.

 
Successful outcomes
 

In the event, considerable progress was made in achieving these objectives. Actual process water characteristics and levels of microbial activity were determined in the participating paper mills, and specifications drawn up for the acceptable minimum water quality standards. This enabled boundary conditions to be set for process improvements whereby contaminants concentrations could be controlled at set points below the critical values. A four-component regime comprising pre-treatment, membrane bioreaction, electrodialysis and electrochemical activation was extensively tested at laboratory and pilot scale, and some redesign has already been implemented in the mills. A settle-plate clarifier for the collection of suspended solids proved considerably superior to the conventional industry system, known as a 'save all'. Removal efficiency was more than 97%, and the solids content of the effluent was more stable. Similarly, pilot-scale investigation of biological digestion indicated that 90 to 95% of the chemical nitrogen demand (CZV) and a high proportion of the chemical oxygen demand (COD) could be eliminated in this way. The membrane bioreactor provided by Dutch partner Triqua also proved capable of destroying biodegradable dyes and colorants. The extraction of dissolved salts by electrodialysis was again highly effective, with removal rates exceeding 70%. Finally, it was shown in laboratory trials that electrochemical activation could be used to produce bleaching agents. Overall, the long-term performance of the technology combination confirmed that this is a valid concept for industrial exploitation. However, the experiments showed that, in some cases, it might be preferable to treat the water as separated streams rather than as a single total effluent. Further research is also considered necessary to verify the commercial potential of electrochemical activation.

 
   Cutting the cost of quality
 

Based on work to date, WA Sanders Papierfabriek Coldenhove has made significant reductions in chemical dosage at its plant in the Netherlands. Modesto Cardella in Italy and Papierfabrik Niederauer Mühle in Germany expect consumption of fresh water to be lowered by at least 30 to 50%, without any loss of product quality. This lower water consumption, together with energy savings, a 10% productivity rise from improved runnability and the possibility to recover and reuse process chemicals, could cut production costs by more than € 10/tonne - worth over € 1 million/year for the participating mills alone.
The project has provided the equipment-manufacturing partners with knowledge and experience that can be turned to the benefit of the European paper industry as a whole, and could also lead to increased market share in export areas.
Ultimately, the results will be applicable to other sectors, such as textiles and foodstuffs, where water plays an essential role in the primary production processes. Meanwhile, by bringing greater understanding of integrated water management and demonstrating the feasibility of clean industrial practices, it is contributing to the health and quality of life for all citizens.

 
See also
Community research on pulp and paper
and

Towards a sustainable future for Europe
   
Balancing economy and environment
Successful outcomes
Cutting the cost of quality
   

Key data

In line with the objectives of the Growth programme's Innovative products, processes and organisation key action, a CRAFT project has enabled a group of paper industry SMEs to enlist expert research support in exploring new techniques that can dramatically reduce water usage and effluent output

Projects

A competitive concept for the paper industry towards zero liquid effluent (BRST 985399)

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