Preparation and characterization of sulfide: Quinone oxidoreductase immobilized carbon matrix for the treatment of sulphide rich post-tanning wastewater

Abstract

Abstract The sulphide present in the Up flow anaerobic sludge blanket reactor treating sulphate rich post tanning wastewater was treated further using Sulfide: Quinone oxidoreductase (SQR) immobilized Carbon- Silica Matrix (CSM) and Functionalized Carbon- Silica Matrix (FCSM) packed bed reactors. The production of SQR from Exiguobacterium aurantiacum was optimized using response surface methodology and it was characterized using FT-IR, XRD and SDS-PAGE analyses. The CSM and FCSM prepared from rice husk were characterized using SEM-EDAX, FT-IR and XRD. The optimum conditions for immobilization of SQR onto CSM were found to be time, 300 min; pH 7.0; temperature 40 °C and enzyme concentration 7 mg g−1. The optimum conditions for immobilization of SQR onto FCSM were time, 240 min; pH 7.0; temperature, 40 °C and enzyme concentration 10 mg g−1 respectively. The immobilization of SQR onto CSM obeyed the Freundlich isotherm model and onto FCSM obeyed the Langmuir isotherm model. The immobilization of SQR onto CSM and FCSM was confirmed by SEM, FT-IR and XRD analysis. The CSM-SQR and FCSM-SQR packed bed reactors were operated separately under continuous mode. The CSM-SQR packed bed reactor eliminated sulphide by 99 ± 0.2% with residual sulphide of 3 ± 1 mg L−1 at the optimum HRT of 15 h. The FCSM-SQR packed bed reactor removed sulphide by 99 ± 0.1% with residual sulphide of 2.5 ± 0.5 mg L−1 at the optimum HRT of 9 h.