Removal of BB9 textile dye by biological, physical, chemical, and electrochemical treatments

Abstract The presence of synthetic azo dyes in water can affect human health and the environment. Conventional treatments are not suitable to remove these synthetic dyes, as most of them have complex structures. In this work, the removal of Basic Blue 9 (BB9) dye was evaluated by using four different wastewater treatments. Biological treatment consisted of a process with microorganisms immobilized in sodium alginate. Chemical treatment was evaluated using ozone. Electrochemical treatment was carried out by electro-Fenton (EF) process using a parallel plate reactor and a carbon cathode. A reactor packed with activated carbon was used as a physical treatment. For each process, BB9 concentration was adjusted based on the removal capacity of the wastewater treatment used. Efficiency was evaluated using absorbance. Immobilized microorganisms degraded 6.61 mg/L within 120 min with an efficiency of 99%. Ozone oxidation degraded a BB9 concentration of 914.7 mg/L with an efficiency of 99% in 100 min. In the electrochemical process, the electrolysis lasted 180 min, where 5.3 mM H2O2 was electrogenerated and a concentration of 29.26 mg/L was degraded in 40 min with a removal efficiency of 97.7%. The physical treatment (adsorption) removed 7.85 mg/L of BB9 with an efficiency of 83.26%. According to the results, all the treatments provided high removal of BB9. Considering that the selection of wastewater treatment is highly dependent on operating expenses, a cost analysis is also presented for the wastewater treatments used.