Fact Sheet - Wastewater

The Wastewater Treatment Process
1. Pump stations collect wastewater and transfer it to the MCUA's Wastewater Treatment Facility.

2. The wastewater is first placed into primary treatment settling tanks to remove solids by gravity, which filters approximately 70% of the particles in the water, leaving mostly dissolved materials.

3. During the secondary treatment process, the wastewater is sent to the aeration tanks. Inside the tanks, the wastewater is further purified by organisms that consume the dissolved materials as a food source. These organisms are naturally occurring, aerobic organisms, which require oxygen. Within these tanks, the organisms are provided an environment in which they can live in a greater concentration than in nature.

4. The filtered and purified water is transferred into final settling tanks, where the organisms are removed by gravity. The majority of the organisms are returned to the reactor. However, each day a percentage has to be removed from the system to keep it in equilibrium. These biosolids and the particles from the primary settling tanks are sent to gravity thickeners and are further concentrated using belt filter presses. The resulting solids are then stabilized by mixing with quicklime and lime kiln dust.

5. After secondary treatment, the water is disinfected with sodium hypochlorite (bleach), tested, and reintroduced into the environment. Approximately 10% of the treated water is used within the plant as cooling water for the power generating facility and other process uses thereby reducing the quantity of clean potable water required for plant operation.

6. The wastewater treatment process is the same that occurs in nature; however the purification that is done in the wastewater treatment plant is completed within 8-12 hours. The entire wastewater treatment plant is powered by energy made from the landfill gas.