There are different technologies for natural gas sweetening in the industry. Natural gas may contain CO2 and H2S, called acid gas. Acid gases are toxic and harmful to human beings. They also cause severe corrosion within the equipment and piping. The process of removing acid gases from natural gas is called sweetening. Acid gases should then be disposed of safely. H2S is converted to elemental sulfur in a sulfur recovery unit. And the remained trace of acid gas is either treated in a tail gas cleanup unit or being incinerated. Choosing the best technology for each of these processes, which suits the specific needs of the projects is a required knowledge for chemical engineers. Getting familiar with the Amine Treating Units and know their operational problems and special design considerations are also necessary for someone who works in the Oil & Gas industry as a design engineer or an operator.