Performance evaluation of SBR for the treatment of dyeing wastewater by simultaneous biological and adsorption processes

In this work, a combination of physical and biological process was employed for the treatment of dyeing wastewater in a sequencing batch reactor (SBR). Mixed culture comprising of white rot fungus (WRFs), Pleurotus floridanus, Ganoderma lucidum and Trametes pubescens, was used as microorganisms in the reactor. Various sorbents were screened for their ability to decolourize the dyeing wastewater. From the results, tamarind seed was found to be the most efficient sorbent and hence it was used in the SBR along with the microorganisms. Statistical design was employed for the optimization of process variables like air flow rate, sludge retention time (SRT) and sorbent dosage. The effects of these variables on decolourization, chemical oxygen demand (COD) reduction and sludge volume index (SVI) were studied. The optimum conditions were: air flow rate – 13 LPH, SRT – 17 d and sorbent dosage – 11 g/L. At the optimized conditions, the performance of SBR was studied at various organic loading rates by changing the initial substrate concentration and HRT. At an organic loading rate of 0.165 kgCOD/m3 d, a maximum decolourization and COD reduction of 86.6% and 96% respectively was achieved. SEM analysis confirms the sorption of dye molecules onto the sorbent.