Decolorization of congo red dye in a continuously operated rotating biological contactor reactor

A continuous study in a rotating biological contactor (RBC) reactor was carried out using poly-urethane foam (PU) surface-immobilized with live fungal biomass of Neurospora crassa with wheat bran adsorbent/substrate for the removal of color from synthetic Congo red (CR) dye wastewater. The experiments were conducted at 303 K, pH 6, to study the effect of various operational para-meters on the CR dye decolorization process. Experimental data confirmed that the amount of biomass produced and % color removal of CR increased with the increase in the number of discs, disc rotation speed, % disc submergence in the liquid medium, wheat bran dosage, and air flow rate. The maximum color removal of 90.15% was obtained using 50 mg L^–1 inlet dyestuff concentration, 20 discs, 16 rpm, 40% disc submergence, 1.5 L min^–1 air flow rate, 1 mL min^–1 dye solution flow rate and 12.5 g L^–1 wheat bran dosage. The activities of various extracellular enzymes of the fungus were measured during the decolorization of synthetic dye wastewater. The results reveal that the cellulase enzyme has a significant role in the decolorization process with its maximum activity and chemical oxygen demand removal being 1,284 U L^–1 and 93.34%, respectively at the end of 240 h.