The Carolina Wastewater Treatment plant, constructed in Loiza, Puerto Rico, services the inland municipality of Carolina. Pictured here is effluent discharge through a diffuser into shallow tropical waters. The extension, made by the Environmental Protection Agency , gives the Puerto Rico Aqueduct and Sewage Authority's Aguadilla treatment plant a 20-year waiver for the discharge of primary treated sewage into coastal waters. Five other applications for waivers are pending in Puerto Rico and approval is expected.
Primary treatment uses a physical process to separate solid materials from sewage.
Advanced primary treatment enhances this process. According to the EPA, primary or advanced primary treatment can provide the required level of environmental protection, but secondary treatment, which uses bacteria and aceration to further break down the sewage, significantly reduces pollutants entering the ocean. A boulder-brain coral thrives in the waters of Culebra, Puerto Rico. Related Sites Learn more about the Clean Water Act at the Environmental Protection Agency .