Microbial population in an aerated thermophilic reactor that treats recycled cardboard plant wastewater

Aerated thermophilic reactors may have advantages for treating industrial effluents discharged at high temperatures. In this study, the wastewater from a recycled packaging cardboard plant was treated at 55 °C in a moving bed aerated reactor. It was observed that, although the overall dissolved oxygen was maintained at 2–3 mg L−1, several anaerobic microorganisms are found either in the mixed liquor or in the attached biofilm. This result indicates that both aerobic and anaerobic mechanisms participate in pollutant removal in this reactor, which confers advantages when recalcitrant compounds are found. The median COD removal efficiency of 84% for 36 h of HRT observed in this experiment is expected for non-optimized activated sludge treatment of high temperatures industrial wastewater.