title: Evaluation of trickle-bed air biofilter performance under periodic stressed operating conditions as a function of styrene loading.
abstract: Trickle-bed air biofilters (TBABs) are suitable for treating volatile organic compounds (VOCs) at a significantly high practical loading because of their controlled environmental conditions. The application of TBAB for treating styrene-contaminated air under periodic backwashing and cyclical nonuse periods at a styrene loading of 0.64-3.17 kg chemical oxygen demand (COD)/m3 x day was the main focus of this study. Consistent long-term efficient performance of TBAB strongly depended on biomass control. A periodic in situ upflow with nutrient solution under media fluidization, that is, backwashing, was approached in this study. Two different nonuse periods were employed to simulate a shutdown for equipment repair or during weekends and holidays. The first is a starvation period without styrene loading, and the second is a stagnant period, which reflects no flow passing through the biofilter. For styrene loadings up to 1.9 kg COD/m3 x day, removal efficiencies consistently above 99% were achieved by conducting a coordinated biomass control strategy, that is, backwashing for 1 hr once per week. Under cyclical nonuse periods for styrene loadings up to 1.27 kg COD/m3 x day, stable long-term performance of the biofilter was maintained at more than 99% removal without employing backwashing. No substantial impact of nonuse periods on the biofilter performance was revealed. However, a coordinated biomass control by backwashing subsequently was unavoidable for attaining consistently high removal efficiency at a styrene loading of 3.17 kg COD/m3 x day. As styrene loading was increased, reacclimation of the biofilter to reach the 99% removal efficiency following backwashing or the nonuse periods was delayed. After the non-use periods, the response of the biofilter was a strong function of the biomass in the bed. No significant difference between the effects of the two different nonuse periods on TBAB performance was observed during the study period.
authors.affiliation: Department of Civil and Environmental Engineering at the University of Cincinnati, Cincinnati, OH 45221-0071, USA.
authors.forename: Daekeun
authors.initials: D
authors.lastname: Kim
authors.forename: Zhangli
authors.initials: Z
authors.lastname: Cai
authors.forename: George A
authors.initials: GA
authors.lastname: Sorial
mesh_terms: D000392:Air Movements; D000397:Air Pollution / Q000517:prevention & control*; D001673:Biodegradation, Environmental; D018533:Biomass; D005374:Filtration; D007700:Kinetics; D020058:Styrene / Q000302:isolation & purification*; D014835:Volatilization
chemical_list: D020058:Styrene