Islamic Republic of Iran is the second largest natural gas (NG) owner in the world (after Russia), possessing around 16% of the global NG reserves (near 975 TCF). It also occupies the third rank among the greatest oil owners (after Saudi Arabia and Canada) by controlling about 11 percent of the global crud oil reserves (around 136 billion barrels of recoverable oil). Since most of these oil and gases are contaminated with hydrogen sulfide, therefore the production of near five thousand tones of elemental sulfur per day from hydrogen sulfide plays an essential role in Iranian natural gas and oil industry. All existing sulfur recovery units (SRU\'s) are using various varieties of Claus processes. Such relatively old units require expensive catalysts while providing low recovery efficiencies (as low as 90 percent or even less). Furthermore, the Iranian officials plan to construct more than 5 SRUs in the next 10 years to produce around 4000 tons of elemental sulfur per day from the south Pars sour gas reserve (the largest NG reservoir in the entire world). This article investigates various environmental aspects of conventional Claus processes and emphasizes on the importance of using novel sulfur recovery technologies such as biotechnology (microbial degradation) and thermal decomposition of hydrogen sulfide (known as thermolysis) to avoid further air pollution of the Persian gulf region. Fortunately, these new technologies not only provide higher sulfur recovery efficiencies (more than 99.4 percent) at relatively low temperatures, but also they produce huge amounts of hydrogen gas which is one of the cleanest sources of energy. Although, the purity of produced hydrogen still does not meet the allowable required criteria, however, it is predicted that the new metallic membranes will provide sufficient means for hydrogen purification in the next few years

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