Operation of Biofilter with Mixed Agricultural Residue as Filter Material: Effects of Humidification and Inlet Hydrogen Sulfide Volume fraction on the Performance

Mixed agricultural residue, inoculated with aerobic sulfide oxidizing microbial consortium, was used as biofilter media to study the removal efficiency (,R) of hydrogen sulfide (H2S). The effect of humidification and inlet H2S volume fraction on the performance of biofilter was also investigated. A 3.9 l bench scale biofilter was continuously operated to treat air containing H2S gas in the range of = 275 to 2833 · 10–6 for 150 days. ,R of 99 % was obtained at = 2020 · 10–6 of inlet H2S volume fraction during continuous operation with humidification. However, ,R dropped to 51 % when the inlet H2S fraction increased beyond = 2020 · 10–6. A maximum elimination productivity of 91 g m–3 H2S of filter bed h-1 and inlet mass loading rate of 91 g m-3 H2S of filter bed h-1 was achieved when the tEBRT was in the range of 15 – 155 s. The filter was operated without the humidifier at the inlet H2S fraction of = 2020 · 10–6 and observed that ,R dropped to 51 % due to the drop in moisture of the filter material. However, R could be recovered up to 83 % upon reintroduction of humidifier into the circuit of biofiltration process indicating, that humidification of the waste gas was essential to achieve the highest possible ,R at particular inlet H2S fraction. The filter recorded ,R above 99 % even in the acidic phase at = 2020 ·10–6 of inlet H2S fraction without intermittent washing. The gas dispersion characteristics were comparable to the previously tested bed materials, offering low-pressure drop across the biofilter in the range of 21 – 74mm of H2O per meter height of packing material

SULFIDE OXIDATION IN A BATCH FLUIDIZED BED BIOREACTOR USING IMMOBILIZED CELLS OF ISOLATED THIOBACILLUS SP. (IICT-SOB-DAIRY-201) AS BIOCATALYST

A study is conducted to test the biological conversion of sulfides using immobilized cells of Thiobacillus sp. in fluidized bed bioreactor. The Thiobacillus sp are isolated from aerobic sludge of distillery and dairy effluent treatment plant using standard methods of isolation and enrichment. Experiments were conducted in a batch fluidized bed bioreactor using calcium alginate immobilized cells of isolated Thiobacillus sp. The batch fluidized bed bioreactor is operated for 168 hours with an initial sulfide concentration of 150 mg/l, at the end of 168 hours 100% sulfide oxidation is achieved by the continuous supply of sterile air as oxidant. During the operational period, biomass concentration, pH, sulfate formation is recorded

Isolation of Thiobacillus sp from aerobic sludge of distillery and dairy effluent treatment plants and its sulfide oxidation activity at different concentrations

Abstract: In the present study two strains of Thiobacillus sp were isolated from aerobic sludge of distillery and dairy effluent treatment plant using standard methods of isolation and enrichment. Experiments were conducted using isolated cultures in batch bioreactor with initial sulfide concentration of 75 and 150 mg/l. The effect of initial sulfide concentration on the activity of isolated Thiobacillus sp was studied. Sulfide oxidizing capacity was also determined at different initial sulfide concentrations. The results from the study indicate the possible isolation of Thiobacillus cultures from native source and application in the full-scale reactor