We also support the Region's community and watershed-based priorities, and actively seek integration of Metal Finishing Common Sense Initiative and pollution prevention concepts and activities into the Pretreatment Program. Finally, the Team works with EPA Headquarters and regions and other stakeholders to develop and implement national policy, ensure national consistency, and to support the National Pretreatment Excellence Awards Program. Treatment plants remove harmful organisms and other contaminants from the sewage so it can be discharged safely into receiving streams. Without treatment, sewage contaminates water supplies and spreads disease. Generally, POTWs are designed to treat domestic sewage only, typically through primary and secondary treatment, and some form of solids handling.
Primary treatment is designed to remove large solids and smaller inorganic grit.
Secondary treatment removes organic contaminants using microorganisms to consume biodegradable organics. In general, however, POTWs are not designed to treat toxic pollutants from industrial or commercial dischargers. Part 403, provides the regulatory basis to require non-domestic dischargers to comply with pretreatment standards to ensure the goals of the Clean Water Act are attained. Categorical pretreatment standards are national, uniform, technology-based standards that apply to discharges to POTWs from specific industrial categories and limit the discharge of specific pollutants. These standards are located at 40 CFR, Chapter I, Subchapter N, Parts 405 - 471.