Optimization of the performance of a thermophilic biotrickling filter for α-pinene removal from polluted air

Abstract

Biodegradation of α-pinene was investigated in a biological thermophilic trickling filter, using a lava rock and polymer beads mixture as packing material. Partition coefficient (PC) between α-pinene and the polymeric material (Hytrel G3548 L) was measured at 50°C. PCs of 57 and 846 were obtained between the polymer and either the water or the gas phase, respectively. BTF experiments were conducted under continuous load feeding. The effect of yeast extract (YE) addition in the recirculating nutrient medium was evaluated. There was a positive relationship between α-pinene biodegradation, CO₂ production and YE addition. A maximum elimination capacity (EC_max) of 98.9 g m⁻³ h⁻¹ was obtained for an α-pinene loading rate of about 121 g m⁻³ h⁻¹ in the presence of 1 g L⁻¹ YE. The EC_max was reduced by half in the absence of YE. It was also found that a decrease in the liquid flow rate enhances α-pinene biodegradation by increasing the EC_max up to 103 g m⁻³ h⁻¹ with a removal efficiency close to 90%. The impact of short-term shock-loads (6 h) was tested under different process conditions. Increasing the pollutant load either 10- or 20-fold resulted in a sudden drop in the BTF's removal capacity, although this effect was attenuated in the presence of YE.

Keywords:

• biotrickling filter
• polymer beads
• thermophilic
• waste-gas
• yeast extract