Degradation of an azo dye using the green macroalga Enteromorpha sp.

This paper documents the biological treatment of C.I. Basic Red 46 (BR46) solution using the green macroalga Enteromorpha sp. A central composite design (CCD) was used for optimisation of the biological decolourisation process. The investigated variables were reaction time, temperature, algal biomass and initial dye concentration. Predicted values were found to be in good agreement with experimental values (R² = 0.988, Adj R² = 0.978), which indicated the suitability of the CCD model for optimising this process. The predicted results from CCD indicated that 83.45% biological dye removal was achieved under optimum conditions with a reaction time of 5 h, a temperature of 25 °C, alga biomass of 2 g and initial dye concentration of 15 mg/L. Biological degradation of BR46 was revealed on the basis of repeated-batch operations and gas chromatography-mass spectrometry analysis. Seven compounds were successfully identified as the biological degradation compounds formed in this process.