An Influence of Temperature on Microbial Removal of Hydrogen Sulphide from Biogas

Hydrogen sulfide (H2S) is a very toxic and dangerous, especially to living organisms, gas. Its other disadvantages are habitual "rotten egg" odor, a corrosivity to concrete and steel and a possibility to cause an atmosphere pollution with sulfur oxides, which are formed during a combustion of the biogas as a fuel. H2S removing (desulfurization) is required for reasons of safety, health, corrosion prevention and atmosphere pollution minimalisation. Hydrogen sulfide removal can be conducted via physical, chemical and biological methods. The main disadvantages of physical and chemical processes are high operating costs, chemicals prices and problems with chemical waste disposal. Biological processes seem to be the most attractive methods for H2S removing from contaminated gases, because of their low required capitals and no significant negative influence on atmosphere. The most popular biological methods of gases purification are biofiltration, bioscrubbing and biotrickling filtration. Biofiltration is a method, which is used especially for odours elimination. There are many factors influencing the biofiltration. One of them is temperature. The influence of temperature on H2S biofiltration process was examined in the paper. The examination was carried out in the organic base POKON. The organic base is a popular artificial substrate for plant cultivation, accessible in a trade. POKON was taken to the experiment without special preparing. Gaseous hydrogen sulfide was produced from concentrated liquid H2SO4 and sodium sulfide in Kipp's apparatus. The substrate samples (in three repetitions) were incubated within 2 weeks in two temperatures: 6 and 28 degrees C, before proper experiment was started. A gaseous hydrogen sulfide was introduced to the headspaces using a syringe till the concentration of H2S reached the values about 48% v/v. The 150 mu l headspace gas samples were then taken from the vials by gas tight syringe through the rubber plugs and analyzed chromatographically (GC Shimadzu 14B). Changes in H2S concentrations, dependent on time, were the basis for the H2S removal rate calculation. Results of a laboratory research on hydrogen sulfide biofiltration using the organic substrate POKON in two temperatures: 6 and 28 degrees C, were presented in the paper. The initial concentration of H2S was up to 48% v/v. The maximum value of hydrogen sulfide removal rate noticed at the temperature of 28 degrees C was 0.19 cm(3) g(-1) (ww) min(-1), while the highest value at the temperature of 6 degrees C was 0.13 cm(3) g(-1) (ww) min(-1), and was 30% lower.