Bioremoval of an azo dye by Azolla filiculoides: Study of growth, photosynthetic pigments and antioxidant enzymes status

In the present study, Azolla filiculoides showed to be able to remove C.I. Basic Red 46 (BR46) from contaminated water up to 99%. The effect of main variables such as reaction time, fern fresh weight, initial dye concentration, pH and temperature were investigated on dye bioremoval efficiency. Reusability experiments confirmed the biodegradation process and six intermediate compounds produced during this process were identified by GC-MS technique. The effects of BR46 concentrations (10 and 20 mg L^-1) on growth, chlorophyll and carotenoide content and activity of antioxidant enzymes including superoxide dismutase, peroxidase and catalase were studied. BR46 treatments resulted in reduction of fern growth. The chlorophylls and total carotenoids content in the treated ferns were not significantly different from the control ones. However, a significant induction in the antioxidant enzymes activity was observed during dye removal process, showing their role in plant protection against the produced free radicals under chemical stress.