Sulfuric acid is a highly corrosive, colorless to slightly yellow liquid that is soluble in water. It is one of the most important industrial chemicals, used mainly in fertilizer production. It is manufactured through two main processes - the contact process and the lead chamber process. The contact process involves burning sulfur to produce sulfur dioxide, catalytically oxidizing the sulfur dioxide to sulfur trioxide, and hydrating the sulfur trioxide to produce sulfuric acid. Wastewater treatment uses sulfuric acid to neutralize pH and remove particles, odors, and pathogens.