SIMULTANEOUS REMOVAL OF COD AND NITRATE FROM MUNICIPAL WASTEWATER: ENHANCING TREATMENT EFFICIENCY WITH A SPOUTED BED REACTOR UTILIZING GRANULAR ACTIVATED CARBON AS BIOFILM SUPPORT MEDIUM

This study investigated the performance of a spouted bed reactor for simultaneous removal of chemical oxygen demand (COD) and nitrate from wastewater using granular activated carbon (GAC) as a biofilm support medium. The reactor had a cylindrical column with a central draft tube made of polyvinyl chloride and was run continuously for 8 hours a day. The experimental wastewater had an initial concentration of 600 mg/L total COD and 40 mg/L nitrate, similar to the higher average composition of municipal wastewater. Compressed air was used to spout the solids in the draft tube, and the experiments were carried out at four different dilution rates (1.2/h, and 1.8/h) with 10 g, 20 g and 30 g loading of GAC. Effluent samples were collected at appropriate time intervals for further analysis. COD removal occurred in the riser through oxidation using air as the oxygen source, while in the annular section, carbon was used as an electron donor for the denitrification process. The results showed that the spouted bed reactor achieved COD and nitrate removal efficiencies of up to 92.5% and 96.7%, respectively, at a dilution rate of 1.2 L/h. with 30 loading. The study demonstrates the potential of spouted bed reactors with GAC as a biofilm support medium for simultaneous removal of COD and nitrate from wastewater.