Aerobic moving bed bioreactor performance: a comparative study of removal efficiencies of kraft mill effluents from Pinus radiata and Eucalyptus globulus as raw material.

A Moving Bed Bioreactor (MBBR) was operated during 333 days. Two different effluents were fed in six different phases. Phases I and II were fed with effluent where Pinus radiata was used as raw material, while phases III to VI were fed with effluent where Eucalyptus globulus was used as raw material. The HRT was reduced from 85 to 4 h, and the BOD(5):N:P ratio (100:5:1, 100:3:1 and 100:1:1) was also simultaneously evaluated as an operation strategy. When MBBR was operated with Pinus radiata influent, the performance presents a high BOD(5) removal level (above 95%), although COD removal is below 60%. Most of the recalcitrant COD contained in the effluent has a molecular weight higher than 10,000 Da. When MBBR was operated with Eucalyptus globulus influent, the performance is around 97.9-97.6% and 68.6-65.1% for BOD(5) and COD, respectively (with HRT up to 17 h). In the Pinus radiata and Eucalyptus globus effluents, the color was mainly found in the molecular weight fraction up to 10,000 Daltons.