Biological Treatment Of Wastewater By Adsorbing Hydrogen Sulfide Gas In The Biogas

H₂S is toxic to biological and crosive to equipment, the presence of H₂S in biogas hinder the use of biogas. To eliminate the H₂S in the biogas has a certain significance to expand the use of biogas. This thesis deals with a development of a new process to use liquid adsorb H₂S in the biogas, and convert sulfide to sulfur by colorless bacteria, thereby reclaiming of sulfur and reducing sulfide contamination. Two types of reactor were investigated its effect of sulfide removal, and possible conditional factor of desulfurization reactor such as: the gas absorbing solution, nutrient, temperature, pH etc, final sum up optimal conditional factor. The sulfur of effluent is difficult to settle down and pose a problem to reclaim the sulfur, we have tested some floccutant's flocculation of effluent.The reactor used in the experiment is self-made up of synthetic glass, which volume is 3 L, and D=12 cm,H=40 cm. The difference between two reactors is whether added Rascing ring paking (D=1 cm,H=0.8 cm). By control DO and temperature of the reactor, when influent sulfide concentration is 200 mg/L and 250 mg/L, the sulfide removal rate of effluent of all-mixed reactor and paking reactor is 95% and 99%, and the load is 4.5⁵ kg/m³·d, 12 kg/m³·d. the paking reactor's SO₄^2- production rate is higher than all-mixed reactor 2³ percentage point.We find that it's better to use river water as adsorbing liqud than the anaerobic effluent of creamers. We select four kinds of nitrogenous nutrients (Urea, potassium nitrate, ammonium chloride and calcium ammonium nitrate), and find it have no effect on desulfurization, there's only slight difference of SO₄^2- production rate among reactor which add in Urea, , ammonium chloride and potassium nitrate, calcium ammonium nitrate. The most suitable temperature for reactor is 20³5℃, at high temperature (above 41℃) the impact of sulfur bacteria is not reversible, low temperature (less than 10℃) inhibit the activity of bacteria, but the slow recovery of temperature bacteria can restore activity. The acid envirment is suitable for SO₄^2- conversion bacteria, and alkaline environment is adverse to both sulfur and sulphate conversion bacteria. The situable pH is 7⁸.5. The low DO is necessary condition to transfer sulfide to sulfur, keeping DO below 2.5 mg/L, can reduce SO₄^2- concentration of effluent.In flocculation experiment, we have tested 2 coagulant and 3 ion types PAM, and we find that PFS is better than PAC in speed up settle velocity and addition proportion, and APAM is better than NPAM. When the addition ratio of PFS, APAM, CPAM is 400 ppm, 250 ppm, 430 ppm can reduce water turbidity under 20 NTU. The cost of 3 selected agent (PFS, APAM, CPAM) is 0.198,0.077,0.105 yuan/m³.