Sewage treatment plants (STPs) use various chemicals to ensure efficient wastewater treatment. These include coagulants and flocculants, like alum or ferric chloride, to help remove suspended solids, and disinfectants such as chlorine or ozone to kill harmful pathogens. Additionally, neutralizers are used to adjust pH levels, and odor control chemicals help mitigate unpleasant smells.... https://www.watertreatmentplants.in/what-chemicals-does-sewage-treatment-plant-use/