Removing Hydrogen Sulfide from the Gas Stream using Biofiltration and Bacterial species Chemolithotrophic – a Review

A major concern among the environmental agencies is the emission of sulfurous gas into the environment. Hydrogen sulfide (H2S) removal from natural gas is particularly required for reasons of health, odour problems, safety and corrosion problems. H2S causes an irritating, rotten egg like smell in concentrations above 1ppm, and at concentrations above 10ppm the toxicological exposure limits are exceeded. One of the technologies commonly used is the hydrodesulfurization (HDS), but this is an expensive process that also requires high temperature and pressure. A complementary alternative to HDS is biodesulfurization (BDS) involving the use of specific microorganisms to the removal of sulfur. Biological desulfurization methods are currently promoted to abiotic methods because they are less expensive and do not produce undesirable materials which must be disposed of. Biofiltration is a process in which microorganisms growing and immobilised on an organic porous material utilise biodegradable compounds. The microorganisms capable of oxidizing H2S are present in a large variety of environment and play an important role in global sulfur cycle. Thus, Biofiltration is a low-cost and highly effective air pollution control technology and an environmental amicable method.