Research Developments for Zero Effluent Kraft Bleach Plants, 1995 Environmental Conference Proceedings

B.J. Fuhr, Ph.D. and D. Henry

Alberta Research Council

D.R. Manolescu

Zerotech Technologies Inc.

T. W.K. Lee, PEng.

Zerotech Technologies Inc.

Zerotech and Alberta Research Council set up a joint research venture to apply the zero effluent technology to kraft bleach plants. The evaporation based water recovery system was first successfully demonstrated at a northern Saskatchewan BCTMP mill in Canada. As part of this program, bleachery effluents from a number of participating kraft mills were characterized. Filtrate samples from acid and alkaline stages were analyzed separately, then mixed and re-analyzed. Distillations were carried out for combined samples to assess effects on the proposed treatment system. To determine the significance of physical and chemical pre-treatment on fouling and scaling propensities as well as distillate quality, the combined sample from one mill was analyzed further. Results indicated that all effluents evaluated to date showed an excellent capture of AOX in the concentrate, with less than 1% of the total AOX in the feed carried over to the distillates. Precipitation of CaCO3 , along with miscellaneous inorganic and organics, was observed during mixing, pre-treatment, and evaporation of the samples. The distillates had low levels of conductivity, TOC, and COD, the latter being mainly due to the presence of volatile compounds such as methanol.