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In the United States, the partially treated waste store in a septic tank is called septage. It generally consists of all the household wastes that are disposed of through a home's plumbing system that neither drain out into the soil nor are converted to gases by the bacteria in the tank.
Disposing of septage in the United States is becoming an increasing problem as people build homes outside of city sewer systems. Septage waste can be transported to local waste water treatment centers, used by farmers for fertilizer, or stored in large septage waste storage facilities for later treatment or use on crops.
Septage is generally split into three parts in a septic tank:
- Scum, which floats to the top and is generally where the bacteria live that treat the waste.
- Effluent, which is the semi-treated liquid that comprises the majority of the material in the septic tank
- Sludge, the solids which collect at the bottom of the tank
Sources of septage
Septage is the material pumped out of a septage tank or onsite sewage facility. Septic tanks can be residential or non-residential. Non-residential sources can include wastewater from commercial/industrial development, grease interceptor as well as other sources such as portable toilet, RV, and boat wastes.
Septage waste is periodically removed (with a frequency depending on tank capacity, system efficiency, and usage level, but typically less often than annually) from these septage tanks by specialized vehicles known as septage, pumper, or "honey" trucks. They pump the septage out of the tank, and transport it to a treatment facility.