On average, each person in the U.S. contributes 50 to 100 gallons of wastewater everyday. Wastewater is also made up of water that collects in street drains during storms, as well as groundwater that enters through cracks in sewers. A wastewater treatment plant removes solids, like sticks and sand, from water. It reduces organic matter and pollutants using helpful bacteria and other microorganisms which consume organic matter in wastewater and are then separated from the water. Treatment plants then restore oxygen to the water to ensure that it can support life in the oceans, lakes, and rivers it is released into.
Wastewater treatment is accomplished in two phases, primary and secondary treatment.
Bar screens let water pass through but filter out trash which is collected and disposed of. A grit chamber slows down the flow of water, allowing sand, grit, and other heavy solids to settle out. A primary sedimentation tank collects the smaller particles. Oxygen speeds the growth of these helpful organisms which consume harmful organic matter. A secondary sedimentation tank allows the microorganisms and solid waste to settle out.