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Growing with oxygen, as in aerobic bacteria and anaerobic bacteria.

Growing without oxygen, as in anaerobic bacteria in a septic tank.

Biochemical Oxygen Demand (BOD):
A standard test that measures the strength of wastewater by determining the quantity of oxygen that is naturally consumed by the wastewater under standard conditions. Generally, it is measured in mg/l.

Chemical Oxygen Demand (COD):
A standard test that measures the amount of the organic matter in wastewater that can be oxidized (burned up) by a very strong chemical oxidant.

The process of destroying pathogenic organisms in water and wastewater.

Dissolved Oxygen:
The concentration of oxygen (normally aged gas) dissolved in water. It is a function of temperature and pressure. The colder the water, the more oxygen it will hold. In general, fish require 5.0 mg/l in a stream.

Domestic Wastewater:
Is limited to that which is generated from sanitary fixtures and appliances, food handling, etc.

Is what receives the wastewater as it exits the septic tank. The drainfield allows for further treatment of the partially treated wastewater as it is pushed along the drainfield by new wastewater entering the field.

The process by which a water body becomes over-enriched with nutrients. While this is a naturally occurring process, it generally results in a less-diversified and less-desirable water body.

An outflow or discharge of waste.

Fecal Coliform:
Indicator bacteria common to the digestive systems of warm-blooded animals that is cultured in standard tests to indicate contamination from sewage or level of disinfection. Generally, measured as colonies/100ml.

Flow Rate (or Discharge or “Q”):
Minimum design pumping rate required to deliver effluent in a timely fashion to gravity system and to pressurize a pressure manifold or LPP laterals.

Industrial Wastewater:
Is wastewater from industrial processes or contaminated with wastewater from industrial processes.

Ground water seeping into a collection system.

Direct rainflow, such as rooftop drains, into a collection system.

The minerals, salts, etc. present in wastewater not attributed to carbon molecules of the organic. Examples, include iron, silver, lead, sodium, etc.

Low Pressure Pipe (LPP):
Lateral 1”-2” pipe with small orifices (5/32”-1/4”) through which effluent is distributed to trench under low pressure (2 to 5 feet).

The minerals and other materials that provide food for living organisms. Traditionally, nitrogen, phosphorus and potassium are thought of as the most important elemental nutrients for streams and lakes.

Onsite Decentralized Wastewater Treatment System:
Individual wastewater treatment systems used to treat and dispose of relatively small volumes of wastewater.

The molecules, cells, etc. in wastewater from living organisms based on elemental carbon.

Discharge hole in a low pressure lateral or pressure manifold.

Organisms that cause disease. Examples in wastewater include Salmonella, Vibro Cholera, Entamoeba histolytica, etc.

A measure of acid or base quality of water that is the negative log of the hydrogen ion concentration. A pH of 7.0 is neutral with 13.0 being very basic and 1.0 being very acidic.

Pressure Manifolds:
3” to 8” pipe with larger orifices (1/2”-1”) through which effluent is distributed to gravity supply lines that in turn feed conventional gravity trenches.

Reserve Drainfield:
Required by many states, an area on your property suitable for a new drainfield system were the current drainfield to fail. This designated area should be treated with the same care as the drainfield itself.

Septic Tanks:
Is a buried, watertight container typically made of concrete, fiberglass or polyethylene. The tank holds the wastewater long enough for the solids to settle out (sludge) and oil and grease to float to the surface (scum). The tank allows partial decomposition of the solid materials. The sludge and scum stay in the tank and compartments and a T-shaped outlet prevents them from leaving the tank.

Total Solids:
The minerals, cells, etc. left in wastewater after evaporation of the water fraction at 103 degrees Celsius. Usually measured in mg/l.

Total Suspended Solids:
The mineral, cells, etc. in wastewater retained on a standard filter paper after filtration, followed by drying at 103 degrees Celsius. Usually measured in mg/l.

The liquids generated from industrial processes; sanitary fixtures and appliances; food handling, etc.

Please Note:
If you are in need of a more extensive glossary or resource of Wastewater Terms, we refer you to the EPA and/or NCDENR Website. Both EPA and NCDENR have a catalog of terms by letter for easy access.

Works Cited
Hoover, Michael T., et al. North Carolina Subsurface Wastewater System Operators Training School Manual. Raleigh, NC: Soil Science Department, College of Agriculture and Life Sciences, North Carolina State University, Raleigh, NC and North Carolina Department of Environment, Health, and Natural Resources, Raleigh, NC, 1996. 3-5-3-6.

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