The document discusses wastewater treatment package plants that offer pre-engineered solutions for treating wastewater using aerobic biological processes. They can be customized to handle different flow rates and pollution levels to safely treat wastewater for discharge or reuse. The plants utilize extended aeration and activated sludge processes similar to nature, employing microorganisms to break down organic waste over several treatment stages including screening, aeration, clarification, and disinfection. They provide a low-cost, easy to operate method for treating wastewater at a variety of industrial, commercial and municipal sites.