Biological deodorization of hydrogen sulfide using porous lava as a carrier of thiobacillus thiooxidans

Biological deodorization of hydrogen sulfide (H₂S) was studied using porous lava as a carrier of Thiobacillus thiooxidans in a laboratory-scale biofilter. Three different samples of porous lava, A, B, and C, which were obtained from Cheju Island in Korea, were used. The water-holding capacities of samples A, B and C were 0.38, 0.25, and 0.47 g-H₂O/g-lava, respectively. The pHs and densities of the lava samples ranged from 8.25-9.24 and 920-1190 kg/m³, respectively. The buffering capacities, expressed as the amount of sulfate added to lower the pH to 4, were 60 g-SO₄^2-/kg-lava for sample A, 50 g-SO₄^2-/kg-lava for B, and 90 g-SO₄^2-/kg-lava for C. To investigate the removal characteristics of H₂S by the lava biofilters, T. thiooxidans was immobilized on the lava samples. Biofilters A and C showed a removal capacity of 428 g-S·m^-3·h^-1 when H₂S was supplied with 428 g-S·m^-3·h^-1 of inlet load at a space velocity (SV) of 300 h^-1. At the same inlet load and SV, the removal capacity of biofilter B was 396 g-S·m^-3·h^-1. The H₂S critical loads of biofilters A, B and C at a SV of 400 h^-1 were 396, 157 and 342 g-S·m^-3·h^-1, respectively. It is suggested that natural, porous lava is a promising candidate as a carrier of microorganisms in biofiltration.