Optimization of propylene glycol removal in a fixed bed activated sludge bioreactor by Taguchi method

Introduction: Taguchi method is an experimental design approach based on, we can predicate theeffect of factors and optimum levels of operational factors with a minimum number of experiments.Propylene glycol is a synthetic organic which can release to the environment and cause health andenvironmental effects. The objective of this study was to determine the optimum conditions of propyleneglycol removal in a fixed bed activated sludge bioreactor by Taguchi method.Materials and Methods: Following the adaptation of microorganisms, which were obtained from amunicipal wastewater treatment plant to different concentrations of propylene glycol in a fixed bedactivated sludge reactor, optimum conditions of operational parameters of bioreactor such as hydraulicretention time, influent COD, source of nitrogen and volume of fixed bed of aeration basin with packingwere determined in three levels by Taguchi method.Results: COD removal efficiency of synthetic wastewater containing N and P based on C:N:P ratio of100:5:1 in the fixed bed activated sludge reactor with HRT of 14 h and influent COD of 500, 700, 900,1100, 1300 and 1500 mg/L was 95%, 92%, 91%, 86%, 81 and 77% respectively. Optimization of theprocess by Taguchi method showed that HRT of 6 hours, influent COD of 1000 mg/L, fixed bed volumeof 30% and NH4Cl as the source of nitrogen with importance priority of 47.96%, 29.927%, 13.25% and8.857% were determined as optimum conditions of operational parameters of the fixed bed activatedsludge rector for propylene glycol biodegradation respectively.Conclusion: Results of this study indicate that by the use of Taguchi method, optimum operationalconditions of fixed bed activated sludge reactor for propylene glycol can be predicted.