Effects of nitrogen source and empty bed residence time on the removal of styrene gaseous emissions by biotrickling filtration.

The removal of styrene-polluted air emissions by biotrickling filtration was performed to evaluate the influence of using nitrate and urea as a nitrogen source in the nutrient solution supplied to two bioreactors run in parallel under the same operational conditions for 3 months. The use of urea resulted in less biomass content along the packed bed and better performance of the process, with a maximum elimination capacity (EC) of 57.6 g C m(-3 )h(-1) (removal efficiency (RE) of 88.3% and empty bed residence time (EBRT) of 60 s), which was around 54% higher than when using nitrate. EBRTs of 60, 30 and 15 s were evaluated with a urea-based nutrient supply. By decreasing the EBRT from 60 to 30 s the styrene concentration that could be treated with REs above 80% was almost the half, from 1,100 to 600 mg C m(-3), resulting in ECs of 52.8 g C m(-3) h(-1). Working at 15 s was not possible to obtain REs higher than 40% with a maximum EC of 28.5 g C m(-3) h(-1).