New application of Orchis mascula as a biocarrier for immobilization of mixed cells for biodegradation and detoxification of reactive azo dyes

In this study, the application of novel biocarrier Orchis mascula plant for immobilization of non-adapted mixed cells biodegrade reactive azo dyes in aqueous solution was investigated via a sequential anaerobic-aerobic process. Three reactive azo dyes including red (RR2), blue (RB4), and yellow (RY15) were individually used as the target pollutants. Results revealed that the immobilized biocatalysts had a potential degrading efficiency, targeting the initial structure and the formed aromatic/aliphatic compounds, respectively. Complete decolorization (100%) of RR2, RB4, and RY15 was observed in the anaerobic phase with significant COD removal which has been enhanced during the subsequent aerobic phase. Results demonstrated that COD removals at 10, 20, and 40 mg/L were 100 ± 0.13%, 95 ± 0.05%, and 90 ± 0.03% for RR2; 90 ± 0.11%, 85 ± 0.9%, and 81 ± 0.18% for RB4; and 100 ± 0.08%, 92 ± 0.16%, and 86 ± 0.06% for RY15, respectively. Immobilized cells exhibited better performance compared with free cells, particularly for high dye concentration up to 100 mg/L.

Keywords: Biocarriers; Biodegradation; Detoxification; Reactive azo dyes; Textile wastewater.