Removal of Styrene from Waste Gas Using a Biological Trickling Filter

Abstract

Biodegradation of styrene in a biological trickling filter on lava stones was investigated, firstly, with the addition of silicon oil and, secondly, without the addition of silicon oil. After 400 days of trial runs the experimental results revealed that the biodegradation capacity of styrene in the trickling filter reached 537 g/m 3 x h with a degradation yield of 96.8 % at an air inlet concentration of 1.06 g/m 3 of styrene and a space velocity of 157 m/h in the presence of silicon oil. A removal of styrene up to 2.9 kg/m 3 x h was obtained when the styrene input concentration in a constant inlet air flow of 0.78 m 3 /h was increased up to 6.6 g/m3. Interestingly, it was observed that after a period of 400 days, the seven dominant strains were completely different from those present in the inoculum. Surprisingly, this population was able to grow in an aqueous liquid phase without silicon oil on a styrene concentration of 45.5 g/L. In the biological trickling filter with lava stones but without silicon oil, the biodegradation capacity of styrene was 464 g/m 3 x h with a removal yield of 98.3 % at an air inlet concentration of 1.03 g/m 3 of styrene and a space velocity of 137 m/h. As in the presence of silicon oil, a removal of styrene of up to 2.375 kg/m 3 x h was achieved when the air flow rate was kept constant and the styrene input concentration was increased. These experiments suggested that the biphasic medium could be very efficiently used for the selection of adapted strains for the removal of insoluble or poorly soluble organic compounds, rather than being used for long-term degradation under industrial conditions.