Optimization by uniform design U8(83) approach for enhanced caffeine degradation in synthetic wastewater in bioreactor

Coffee wastewater contains large amounts of caffeine which affects microflora and seed development to great extent. Although several physio‐chemical methods available for caffeine degradation, they are not preferred for large‐scale treatment. In this study, we optimized induced cell concentration, aeration and agitation rate for maximizing caffeine degradation rate in bioreactor using Uniform design. Maximum caffeine degradation rate of 23·59 mg L−1 h−1 was achieved. The reduction in chemical oxygen demand, biological oxygen demand and total organic carbon removal were found to be 72, 78 and 72% respectively. Mathematical model was developed through regression analysis and predicted maximum caffeine degradation rate of 24·2 mg L−1 h−1 under optimal conditions of 0·35 g L−1 biomass, 395 rev min−1 and 1·62 vvm. Experimental validation at optimum condition resulted in 22 mg L−1 h−1 of caffeine degradation rate. This is the first‐ever bioreactor study showing highest caffeine degradation rate in synthetic coffee wastewater with limited experimental runs. Significance and Impact of the Study: Caffeine degradation in coffee wastewater is crucial but less explored area in current treatment strategies. This research focus on the caffeine degradation in a reactor where we used uniform design methodology and mathematical model derived from its data. Experimental design yielded a highest caffeine degradation of 23·59 mg L−1 h−1 at 0·3 g L−1 biomass, 200 rev min−1 and 1·8 vvm which is highest ever reported along with reduction of critical parameters like COD, BOD and TOC. Regression model developed from experimental data predicted an optimum caffeine degradation rate of 24·2 mg L−1 h−1 at 0·35 g L−1, 395 rev min−1 and 1·62 vvm which was confirmed experimentally.