Biodegradation of gaseous toluene with mixed microbial consortium in a biofilter: steady state and transient...

Petroleum oil refineries are massive emitters of risky volatile organic compounds (VOCs). Among the VOCs, toluene is taken into account as a significant pollutant. In the present study, a compost biofilter is used to treat the toluene vapor. However, an elimination capacity and removal efficiency of the biofilter was investigated for a wide range of toluene concentrations (0.29-3.8 g m^-3) and operated for 54 days effectively. Elimination capacity of 93 g m^-3 h^-1 was recorded as maximum value at a toluene inlet concentration of 114 g m^-3 h^-1. An elimination capacity was perpetually better at the lower section of the biofilter, and therefore, the value was around 40-60 g m^-3 h^-1. The high removal efficiency of 97% was obtained at inlet toluene load of 60.55 g m^-3 h^-1. Hence, the biofilm was quite sensitive to handling transient loading conditions. The pressure drop had no vital impact on the biofilter performance. An Ottengraf model was applied to all phase of biofilter operation in each of the diffusion limiting region and reaction limiting region. The parameters of the model K ₁ (75.95 g^1/2 m^-3/2 h^-1) and K ₀ (90.51 g m^-3 h^-1) were obtained from diffusion and reaction limiting region severally. However, K ₁ was used to calculate the theoretical elimination capacities, and therefore, K ₀ was used to discover the biofilm thickness. By the way, the average biofilm thickness was found to be 0.98 mm from reaction limiting region.