Avaliação do tratamento de efluente de indústria de celulose kraft por processo de bioaumentação com bactérias isoladas de lagoa aerada facultativa para remoção de compostos específicos

Abstract

In this study, the treatment of Kraft effluent was evaluated by a bioaugmentation process with isolated, selected and cultured bacteria capable of removing specific compounds based on an aerated facultative lagoon (AFL) treatment system. The AFL were operated with organic load rate (OLR) of 0.2 and 0.6 kg COD m­3 d­1, called Phase I and Phase II respectively, for a period of 120 days. The efficiency was assessed by the removal of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total organic carbon (TOC), color, turbidity, total phenolic compounds (TPC) and compounds derived from lignin. Analyses of fluorescence excitation­emission matrix (EEM), biomass development through total and volatile suspended solids (TSS and VSS), acute ecotoxicity of the affluent and effluent of the treatment and microbiology diversity were performed. It was possible to observe that the removal of organic matter in terms of BOD5, COD and TOC were efficient in both phases, reaching a total of 94%, 51% and 49% (Phase I) and 80%, 44% and 41% (Phase II) respectively. Color and TPC were not significantly removed during biological treatment. Turbidity was removed by 94% in Phase I and 87% in Phase II. However, compounds derived from lignin had an average removal of 13% in Phase I and 27% in Phase II. From the EEM analysis, it was observed a decrease in the intensity of emission of fluorogenic compounds present in the treated effluent samples. The biomass reached an VSS/TSS ratio of 0.67 in Phase I and 0.62 in Phase II after 60 days of operation of each AFL. No acute toxicity was observed in industrial samples before or after treatment. Nine bacterial species were identified in Phase I and 12 species in Phase II due to statistical similarity. Of the microorganisms identified, isolated or combined ones (Bacillus cereus, Bacillus thuringiensis and Paenibacillus glucanolyticus), both associated with biomass, proved to be efficient with color removal in 69%, 48%, 38% and 45% respectively and TPC by 37%, 21%, 8% and 13% respectively. This performance surpassed that exclusive to biomass, indicating that the species Bacillus cereus, Bacillus thuringiensis and Paenibacillus glucanolyticus were effective in the treatment of specific cellulose effluent compounds.