Biodegradation of Nicotine Using Aerobic Granules in Sequence Batch Reactor

Nicotine is a substance widely consumed globally as a drug. Due to its toxic nature and high solubility in water, it poses a significant threat to water quality. This study aimed to investigate the feasibility of forming aerobic granules from nicotine-acclimated activated sludge and examine the capability of these aerobic granules for nicotine degradation. The acclimation process led to the complete degradation of 500 mg/L of nicotine. Ultimately, the effluent concentrations of nicotine and COD were 3.4 mg/L and 53 mg/L, respectively, with the system achieving removal efficiencies of 99.14% for nicotine and 89.16% for COD. Additionally, a 6-hour cycle (1 minute filling, 10-1 minute settling, 1 minute discharge, and the remaining time for aeration) resulted in the formation of granules with diameters ranging from 2-4 millimeters and a round shape, exhibiting high strength. After 60 days, the SVI30/SVI5 ratio reached 1.0. The granular sludge showed higher extracellular polymeric substances and protein content compared to flocculent sludge, with a protein-to-polysaccharide ratio of 2.64. Furthermore, to assess the aerobic granules' ability to degrade and tolerate nicotine toxicity, the nicotine concentration was increased to twice the adapted concentration (1000 mg/L), resulting in a COD removal efficiency of 90.2% in the aerobic granular sequencing batch reactor.