| Process Modifications Reduced Discharge at a French Pulp and Paper Plant | France | 1993 | Full scale |
MANUFACTURE OF PAPER AND PAPER PRODUCTS # 43
Background
LA CELLULOSE DU RHONE ET D AQUITAINE decided in 1990 to increase their production of white kraft pulp by 130 000 tons a year, bringing it up to 320 000 tons. In order to respect the quality requirements of the River Garonne, (which supplies more than 600 000 inhabitants with drinking water) they had to reduce the discharge water by half.
Cleaner Production Principle
Process modification
Cleaner Production Application
CDRA chose to build one chain to treat both types of wood alternately instead of doubling the existing chain of broad - leaved trees.
The work was carried out in several steps so as not to interrupt the production.
The new line consists of an extended firing partly carried out against the current; the end of firing ensured by a new white liquor without lignin. The re-precipitation of lignin is avoided in a portion of the firing liquor. At the end of firing, the pulp contains 2.5% of lignin rather than 4% using a classical process, for broad leaved trees. The lignin extracted is in the black liquor incinerated in the boiler.
The pulp is then purified in a rotary vacuum filter, washed and concentrated at 12%. The purified waste is recycled at the treatment plant inlet. The content in oxidisable matter of the effluent is thus reduced to under 10 kg/ton of pulp.
| Extended firing, washing under pressure. |
| Lignin removal using oxygen. |
| Chlorine dioxide - bleaching. |
| Evaporation of black liquors for incinerating in the boiler. |
| Recirculation of bleaching effluents into the black liquors. |
Material/energy balance and substitution
| Average 1992 | Average 1993 | After biological treatment plant | |
| Production t/d | 600 | 653 | 800 |
| COD flow t/d | 32.8 | 15.9 | 11.0 |
| BOD flow t/d | 8.4 | 6.2 | 1.4 |
| Colored flow t/d | 40 | 16.6 | 12 |
| Organo chlorinated products t/d | 0.5 | 0.2 | 0.05 |
Environmental and Economic Benefits
| The industry improved productivity and could diversify products to customers interested in the coniferous trees pulp, within a context of pulp price fall (5100 F/t in 1989, against 2 200 F/t in 1993). |
| The reduction in the effluents load of this new line made possible the building of a treatment plant common to CDRA and St-Gaudens city. |
| This modern line reduces the risks of accidental pollution. |
Cost of direct investment
| Extended firing, extensive washing | 57 000 000 |
| Oxygen-bleaching | 108 000 000 |
| Total | 165 000 000 FF (1992) |
Constraints
None reported.
Contacts
Review Status
This case study was submitted to UNEP IE in 1994 by the French Office International de l'Eau.
Subsequently the case study has undergone a technical review by Dr Prasad Modak at Environmental Management Centre, Mumbai, India, in September 1998.