製紙業界における嫌気性排水・用水処理の適用

抄録

Since the beginning of the eighties, anaerobic effluent treatment plants have been applied in the paper industry. The UASB reactor has become the most popular reactor. It is operating on almost all types of paper industry effluents, but the largest numbers can be found in the paper recycling industry. When acid paper sizing was abandoned, circumstances for fresh water reduction im-proved considerably, so that process waters and resulting effluents became much more concentrated in COD.
Increased water hardness, due to CaCO₃ in the waste paper, causes heavy biomass flocs and granules. Mixing problems are overcome by the application of a new generation of reactors (IC reactors).
Paper manufacturing often takes place at temperatures of 55°C, due to better dewatering in the press section and subsequent steam savings in the drying section. The high temperatures can he best achieved in closed water circuit. Biological process water treatment remain necessary in the closed circuit, due to contamination problems (odours).
In order not to loose too much energy for cooling the water before the biological treatment, extensive research has been started for thermophilic treatment. This process could he quite attractive for several reasons. The first indications are quite positive. For the future, it is expected that many recycle/packaging grade mills will move to effluent-free operation with new cost-efficient in-line biological treatment concepts.