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Graphic element Research > Growth > Research projects > Cross-disciplinary projects > Paper mill shows the way in environmental care
Graphic element Paper mill shows the way in environmental care
    25-09-2001
 

The European pulp and paper industry is committed to maximising the environmental friendliness of its production practices, as reflected in efforts made at the paper mill of Oudegem Papier in Belgium. A notable feature of the facility is its sophisticated water treatment system, which draws on innovative research carried out in the European Commission funded PAPER KIDNEY project.

Oudegem Papier is part of the VPK Packaging Group , one of the leading western European suppliers of paper-based packaging materials. The paper mill in Dendermonde specialises in production of cardboard, test liner and fluting based on recycled fibre.
Locally collected recovered paper is processed at the mill to produce papers for corrugated board, solid board, tubes and cores. The facility is centrally located in a densely populated area of Flanders, northern Belgium, which generates an inexhaustible supply of raw material. In 2000, its three specialised paper machines produced a total output of 320,000 tonnes, consuming more than half of all the recycled paper collected in the Flanders region.

Essential resource
 

Water is a key resource in paper manufacture. To achieve its current production, Oudegem Papier pumps 1,000,000 m³/year of water from the River Dender. Although a large volume, this level of consumption is among the lowest in Europe for such processes. Every effort is made to reuse as much water as possible, and to keep effluent discharges to a minimum. To this end, Oudegem Papier has an ultra-modern water purification installation that is constantly being optimised and refined.
The site was equipped with a modern anaerobic and aerobic effluent treatment system in 1994, capable of handling up to 150 m³/h of effluent. However, this had developed problems with calcium carbonate (CaCO3) precipitation in the water treatment plant, due to a gradual increase of calcium levels by the restricted effluent volume allowed.
The anaerobic sludge lost activity due to the participation of CaCO3 on the pallets, and the aerobic sludge was tending to accumulate so much CaCO3 that it settled to form a thick layer of sediment on the bottom of the aeration tanks.
In addition, VPK planned to increase production to over 450,000 tonnes/year. It therefore decided to invest an additional € 4 million in an extended system for the mill, which would improve the internal water quality by reducing the COD (chemical oxygen demand - a measure of pollution) in the circuit from above 10,000 to below 5,000 mg/l in order to avoid calcium precipitation. The ultimate objective is to reach a quasi-complete closure of the water cycles, so that no more water needs to be discharged into the river.

 
Innovative techniques
 

The new equipment employs innovative purification processes developed under the European Commission FP5 Growth project PAPER KIDNEY (advanced water treatment technologies for kidney operating of zero effluent water systems for paper and board production), of which VPK was a consortium member.
The major breakthrough for PAPER KIDNEY was the idea of cleaning up the internal water loops by an anaerobic thermophilic internal circulation reactor (ICR) instead of investing in an extension of the existing water treatment plant.
An initial advantage of this technology is the cultivation of thermo-tolerant bacteria, which could digest the pollutants under anaerobic conditions at around 55ºC: the actual temperature of the process water. Previously, it had been necessary to cool the water before treatment, resulting in a considerable waste of energy. Another benefit is the ability to use a vertical design for the reactor tanks, with a smaller footprint that reduces the risk of calcium precipitation. And, by cleaning up the internal water system, biogas is produced that is reused as a reliable and renewable fuel supply with high energy efficiency for the steam production.
Commissioned in 1999, the system takes 385 m³/h of non-cooled clarified water and returns it to the mill circuit after purification. With this improved internal water quality, the previously existing treatment plant can function well within its capabilities.

 
See also
Community research on pulp and paper
and

Towards a sustainable future for Europe
   
Essential resource
Innovative techniques
   

Key data

Under the Innovative products, processes and organisation key action, PAPER KIDNEY is determining the feasibility of minimising paper mills' water consumption without compromising product quality.

Projects

PAPER KIDNEY Advanced water treatment technologies for kidney operating of zero effluent water systems for paper and board production (BRPR988002)

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