Microbial community evolution in the biofilm attached to sponge carriers in pulp mill effluent treatment

This study investigates the evolution of the biofilm matrix responsible for treating effluent from a pulp mill and identifies the microbial community by 16S rRNA gene sequencing. In addition, a biocarrier promising a functional structure with better specific features for biofilm formation than traditional polyurethane carriers was explored. The average removal efficiencies were 43.7% for chemical oxygen demand (COD) and 62.7% for biochemical oxygen demand (BOD5). The color increased during the treatment, indicating anoxic zones being formed in the inner part of this type of carrier. Periodic micrographs showed the evolution of extracellular polymeric substances and materials like fungi and bacteria adhered to the carriers. Genetic sequencing confirmed the presence of Bacillus sp. and Paenibacillus glucanolyticus, species with the potential to degrade and discolor pulp industrial effluents. Results offer a potential basis to enhance treatment facilities of pulp and paper mills based on microbial activities.