HYDROGEN SULFIDE (H2S)
Hydrogen Sulfide (H2S) Removal Gas Upgrading Systems
Since the average H2S concentrations is >400 ppm, a biological H2S removal system has been proposed to reduce most the H2S. Biogas is first processed through a continuously-operating bioscrubber with microorganisms that reduce H2S to sulfuric acid. These sulfur-metabolizing microorganisms grow on media inside a FRP tank. After passing the biological scrubbing tower, the H2S concentration of the landfill gas is reduced to less than 50 ppm. The system requires only fresh water and standard commercial fertilizer (nitrate, potassium, phosphorus).
For the additional H2S polishing of biogas, it is heated to a temperature of approximately 140° and fed through two vessels (lead/lag) filled with catalytic- active activated carbon to adsorb hydrogen sulfide and produce sulfur and water through a reaction with oxygen, as shown below:
2 H2S + O2 → ¼ S8 + 2 H2O
While water evaporates, the sulfur remains irreversibly in the activated carbon.
• No chemicals (i.e. NaOH, H2O2 or iron) required, therefore, no associated disposal cost
• Biological desulfurization requires only fertilizer and water
• Optimized operation cost due to bulk H2S removal with biological scrubber1
• Highly reliable even in case of H2S peaks exceeding a multiple of the average value
• Sulfur-free landfill gas upstream of PSA upgrading system increases lifetime of the adsorbent2