Aerated Facultative Lagoons Performance Bioaugmented With Bacillus Thuringiensis Immobilized On Rice Husks for Treatment of Cellulose Effluents

Abstract

Abstract This study evaluated the performance of bench and pilot-scale facultative aerated lagoons (FAL) treating Kraft pulp effluents subjected to organic load shocks, with bioaugmentation of Bacillus thuringiensis NR114581.1 immobilized on rice husks. The effluents from the treatments were characterized in terms of chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ), specific lignin compounds, color, and turbidity. Batch tests were performed to optimize the bioproduct dosage and evaluate its removal performance. During bioaugmentation in the bench-scale FAL, the average removal reached 72% for BOD 5 and 36% for COD, while the removal of specific compounds was low or zero. In the pilot system, a consistent performance under shock conditions was observed, with removals of 60% for BOD 5 and 54% for COD, with limited removal of specific compounds. The biotransformation of organic matter was evaluated using fluorescence excitation-emission matrix (FEEM) analysis, revealing reductions and increases related to fluorophores associated with protein-like and humic compounds. The microfauna presented typical ecological succession, with predominance of crawling ciliates and metazoans in both systems. Variations in abundance indicated the sensitivity of the systems when subjected to disturbances. The immobilization of bacteria on rice husks with biofilm formation was associated with system performance under the evaluated conditions. The results support the use of FEEM analysis and microfauna monitoring as diagnostic tools for evaluating the performance and resilience of FAL applied to load shocks and bioaugmentation.