Thesis (M.Sc.)--Chulalongkorn University, 2008

Removal of hydrogen sulfide (H₂S) was investigate in a laboratory-biofilter packed with selected activated sludge cultures immobilized on plastic cap and ceramic as packing materials. The results showed that relatively higher amounts of microorganisms from the activated sludge treating tofu wastewater were observed on the media having only thiosulfate as the energy source (TSA medium) compared to those from the activated sludge treating domestic wastewater. The cell numbers up to 2.8×10¹¹ cfu/L of packing material were achieved on ceramic. Results from the study of effects of factors on H2S removal found that space velocity (SV) significantly affected H₂S removal. Nearly complete H₂S removal was achieved at low SV (10 h⁻¹). Possible interaction effects were also observed, e.g. between type of packing materials and rate of sprayed water. Microorganisms growing in the high H₂S removing biofilter were shown to function at higher kinetic activity (2.7×10⁻¹⁴- 8.4×10⁻¹² mg H₂S removed/ cfu.min). The maximum removal capacity achieved in this study was 132 g H₂S/m³.h for plastic cap at H₂S loading rate of 183 g/m³.h and 118 g H₂S /m³.h for ceramic at H₂S loading rate of 124 g/m³.h. The main end products of H₂S oxidation were SO₄²⁻ and S⁰.