There are several factors affecting the cost of cleaning wastewater, including energy, chemicals, and reinvestment in the collection and treatment systems. Pollutants in the wastewater must be removed to ensure the protection of public health, aquatic life and the environment before returning it to the environment. The cleaned water must meet water quality requirements.
The treatment process not only eliminates disease-causing bacteria to protect the environment for human and aquatic life, but also removes other elements such as ammonia, which can be harmful to fish, as well as nitrogen and phosphorus. These nutrients can cause excessive algae growth in streams, rivers and lakes.