SEQUENTIAL TREATMENT OF E1 STAGE KRAFT BLEACH PLANT EFFLUENT

The effluent discharge from a kraft bleach plant contains large amounts of chlorinated organics. These chlorinated organics, termed chlorolignins, are produced by chlorine addition to residual lignin in the unbleached pulp. They can be problematic in the environment, and the paper industry would prefer they not be discharged. However, effective means to destroy chlorinated organics from the bleach plant have not been developed. The objective of this study was to evaluate two flowsheets for the destruction of these chlorinated organics. The first flowsheet consisted of an RBC, on which a white rot fungus had been immobilized, followed by an anaerobic digester. The second flowsheet consisted of an aerated lagoon followed by an anaerobic digester. It was found that the fungal/anaerobic digester sequential treatment was more effective than the other treatment scheme because the fungus was able to metabolize the chlorinated organics and attack the chlorolignins thereby making them more amenable to degradation by bacteria.