Primary Treatment - The first stage of the wastewater treatment process at the facility in which mechanical procedures are used to remove pollutants.

Secondary Treatment - The second stage in wastewater treatment in which microorganisms consume the organic parts of the waste.

Effluent - Water that flows from a treatment facility after the wastewater has been treated.

Microorganisms - Small living organisms, including bacteria. Some species consume the organic part of sewage.

Sewer - A system of underground pipes that collect and deliver wastewater to treatment facilities.

Wastewater - Polluted water that has been used in homes, schools, businesses, and industries that is not suitable for reuse prior to treatment.

Wastewater-treatment facility - A facility with a series of tanks, screens, filters, and other processes used to clean wastewater before it is returned to the environment.

Lagoon - A treatment pond that uses sunlight, algae, microorganisms, and oxygen to remove organic matter and nutrients from wastewater.

Wetland - A naturally occurring filtering system that improves water quality by reducing nutrients while providing wildlife habitat.

Sludge Treatment - Sludge is that part of wastewater that settles to the bottom. Sludge is removed from the bottom of tanks and filters. Prior to use or disposal, sludge is treated with chemicals and heat to kill disease-causing organisms and decrease the water content.

Clarifier - A structure that lets solids in wastewater settle to the bottom and make sludge.