Abstract

The European paper industry produces 70 million tonnes of paper annually and at the same time uses an average of 20 m³/t (1.4 billions m³ of water annually). Paper and board production therefore is one of the most water intensive industrial processes. The reduction of wastewater has already led to a re-circulation rate of more than 90% of the water and some mills even produce paper in a closed cycle. This results in severe quality deterioration and a drop of productivity (machine failures, slime formation, odour), which often force paper makers to reopen their system again. Existing treatment technologies for closed loop operation show significant limitations. The objective of the proposed research work is to develop a suitable treatment technology (kidney technology) for closed cycle operation in order to realise effluent free paper production.

Two different approaches to integrated treatment are to be investigated:

• Pressurised thermophilic aerobic treatment with integrated biomass separation via membrane or flotation and;
• Thermophilic anaerobic treatment combined with ultrafiltration.

The technology to develop is to be operated at increased temperatures enabling paper production at 55 to 60 degrees C with significant positive effects on productivity (+5 %) and energy consumption (>-5 %). Due to high biomass concentrations (20-25g/l), high temperatures and the use of membranes the treatment technology will require less space in installation. Waste production can be reduced sharply in relation to existing technologies (40 to -90%). The specific COD loading rate of the biological stage will be increased (> +50%) compared to conventional (mesophilic) treatment.

The kidney technology should be able to be operated with little energy consumption or should even produce energy. This process will significantly improve the quality of recycled water due to the use of membrane technology. The technology will be developed for systems producing packaging grades from 100% waste paper. The results should also be able to be used to develop kidney technologies for higher paper grades and other branches of industry with high organic loads in waste waters (e.g. food etc.) and extensive water use. Lab scale tests for process development and pilot scale tests (in 2 paper mills) will be carried out for both technologies.

A detailed mill scale implementation study will be conducted in the participating paper mills.

The consortium comprises two research institutes with specific know how on paper production and biological degradation, three suppliers of wastewater treatment and two paper mills as end users of kidney technology producing packaging grades of paper.

Contacts

Coordinator

• Dieter PAULY / PTS Munich GERMANY

Participant

• Fidel IGNACIO PLAZA / Cadagua SA Departamento I + D / SPAIN
• Luis LARRERA / Centro de Estudios e Investigaciones Técnicas de Guipuzcoa / SPAIN
• Hans NOHLES / John Zink International Luxembourg Sarl LUXEMBOURG
• Ann DESCHILDRE / Oudegem Papier NV BELGIUM
• Leo HABETS / Paques BV NETHERLANDS
• Miguel AZNAR / Sociedad Anonima Industrias Celulosa Aragonesa Departamento de Medio Ambiente / SPAIN