Removal of hydrogen sulfide and methyl mercaptan by a packed tower with immobilized micro-organism beads

To develop a more effective process for removing H2S and methyl mercaptan (MeSH), which are the important odorous components emitted from wastewater treatment facilities, a packed bed filled with immobilized micro-organism beads was studied. This study encompassed bacteria enrichment, evaluation of bacteria immobilization methods, determination of optimum operation parameters, such as environmental conditions for bacteria growth, removal rate of the packed bed etc. The experimental results are shown as follows: (1) the cultures able to metabolize H2S and MeSH can be enriched from activated sludge and the enrichment periods are 1-2 days and 7-10 days for H2S and MeSH, respectively; (2) the key environmental parameter influencing the cultures is pH value, the suitable ranges are 2-3 and 6-8 for H2S and MeSH, respectively; (3) the maximum removal rate for H2S and MeSH are 6500 g/m3 bed d and 4 g/m3 bed d, respectively; (4) the superficial M-M kinetics parameters are Vm: 11.2 g S/kg dry beads h and Ks: 95.8 mg/m3 for H2S, and Vm: 0.052 g S/kg dry beads and Ks: 2.1 mg/m3 for MeSH; (5) a two-stage biofilter operated in series under different pH values is recommended, which can remove the H2S and MeSH effectively.