Sequential batch reactors for aerobic and anaerobic dye removal: A mini-review

Abstract

One of the most challenging aspects of environmental conservation is the treatment of dye wastewater. Thus, this mini-review discussed the issues and major advances in the application and performance assessment of the aerobic, anaerobic, anaerobic-aerobic, aerobic-anaerobic, and anoxic–aerobic REACT-operated SBR systems with regards to bio-decolorization and COD removal rates. In SBRs run in aerobic modes, it is possible to cultivate aerobic granular sludge for color removal. To be precise, SBR has a higher COD removal efficiency with a lower color removal efficiency. Under anaerobic conditions, lesser COD removal was observed for several dyes studied in this chapter. In an alternating anaerobic-aerobic SBR system, color removal tends to occur during the anaerobic phase, while the aerobic phase is required to further reduce the effluent COD concentration. However, molecular oxygen drastically reduced color removal in SBR during dye wastewater treatment. This chapter discusses the aerobic-SBR treatment process for dye removal. The discussion focused on dye wastewater treatment using aerobic granules, granular activated carbon, adsorbents, biocarrier white rot fungi, varying dye mixtures, dye concentrations and SBR operational parameters. Adsorbents, membranes, biocarriers, exported microbial cultures, and various operational conditions have also been used in sequential anaerobic/aerobic batch reactors to enhance system performance. This chapter assessed the different treatment mechanisms and dynamics and concluded that combining two treatment methods significantly yields better color, DOC, and BOD5 removal than a single biological or chemical treatment.