A pilot-study on treatment of a waste gas containing butyl acetate, n-butyl alcohol and phenylacetic acid from pharmaceutical factory by bio-trickling filter

A bio-trickling filter packed with fibrous balls, ZX02, packing material was tested to treat a mixed waste gas containing butyl acetate (BA), n-butyl alcohol (n-BA) and phenylacetic acid (PA), which were discharged from penicillin workshop in a pharmaceutical factory. In order to investigate the effect of various factors such as inlet loading and spray water flow rate on the removal rate of these three volatile pollutants, a field experiment was carried out continuously for more than 3 months using a pilot bio-trickling filter and effluent from a wastewater treatment plant was used as spray water during the pilot experiment. The removal rates of BA, n-BA and PA was 95%, 92% and nearly 100%, when their inlet concentration was lower than 2200, 2400 and 370 mg m−3, respectively. To maintain 90% removal of BA, n-BA and PA, acceptable maximum inlet loadings cannot exceed 373.4, 317.2 and 209.5 g m−3 h−1, respectively. The effluent from the secondary sedimentation tank of the pharmaceutical wastewater treatment plant can be used as spray water, and its optimal flow rate was determined to be 9.5–10.5 L h−1. The bio-trickling filter had significant ability to resist shock of high inlet loading while maintaining low resistances to air flow. Therefore, it can be operated for long-term without frequent backwashing.