EVALUATION OF TRICKLE-BED AIR BIOFILTER PERFORMANCE FOR STYRENE REMOVAL

A pilot-scale trickle-bed air biofilter (TBAB) was evaluated for the r emoval of styrene from a waste gas stream. Six-millimeter (6-mm) Celit e pellets (R-635) were used as the biological attachment medium. The o perating parameters considered in the study included the styrene volum etric loading, the empty-bed residence time (EBRT), the frequency End duration of backwashing, and nutrient-phosphorous (nutrient-P) managem ent as a biomass control strategy. The aim of the study was to demonst rate that high removal efficiencies could be sustained over a long per iod. Periodic backwashing of the biofilter with full-medium fluidizati on was necessary for removing excess biomass and attaining stable, lon gterm high removal efficiencies. Styrene removal efficiencies in the 9 9% + level were achieved for volumetric loading rates up to 2.93 kg CO D/m(3).day and a 1-min EBRT. With a COD volumetric loading rate of 4.2 6 kg COD/m(3).day and a 0.67-min EBRT, removal efficiencies in the 97- 99% level were achieved. Evaluations of pseudo steady-state performanc e data, 1 day following backwashing, yielded first order removal rate constants that were dependent on EBRT. Nutrient-phosphorus (nutrient-P ) limitations Failed to provide a strategy for biomass control while a t the same time maintaining acceptable performance. (C) 1998 Elsevier Science Ltd. All rights reserved.