Acid gases have an anthropic origin: in other words, they are generated by human activity. Most of these emissions are generated by fossil fuel industries, in which compounds containing sulfur or chlorine are burned.
When these fuels are burned, they generate molecules, which combine with water in the atmosphere to form acid rain. As a result, they are very dangerous for the environment.
Since they are acidic in nature, they are treated with dry, semi-wet and wet systems.
- Dry systems: these systems use lime or baking soda in the form of dry powder to react with acid compounds. Then, bag filters can be used to remove solid particles.
- Semi-wet systems: these systems are based on absorption by spraying. The absorbent agent is injected, in the form of a suspension, into the gas to be treated into a contact reactor. A subsequent filtering phase is also required.
- Wet systems: these systems commonly use scrubbers with a basic solution (usually with caustic soda, NaOH) to neutralize acid gases.