EFFLUENT QUALITY IN DIFFERENT COMBINATIONS OF BLEACHING SEQUENCES AT ARACRUZ

The pulping processes of Aracruz Celulose were optimized and the modif ications allowed a significant improvement in the effluent quality. A strong col relation between kappa number and effluent characteristics was observed. Trials with different combinations of four simultaneous bleaching sequences were carried out using conventional (60% ClO2 in c hlorination stage), ECF and TCF bleaching. Results showed reductions o f color, AOX, COD and BOD, indicating that the right bleaching combina tion could be a tool used to optimize effluent quality.