Activated Sludge -- term given to a method of wastewater treatment that uses aerobic and facultative bacteria in suspension to remove wastes. Activated sludge is a popular method of treatment, and dozens of variations on the basic process exist.
Aerobic bacteria -- bacteria that require the presence of free or dissolved oxygen in their environment for survival and reproduction.
Alabama Department of Environmental Management (ADEM) -- State of Alabama agency tasked with, among other duties, ensuring that wastewater treatment plants perform adequately and with enforcement when they do not.
Anaerobic bacteria -- bacteria that live and reproduce in an environment that contains no free or dissolved oxygen. They get their required oxygen by breaking down chemical compounds that contain oxygen such as sulfate (SO4) or nitrate (NO3).
Bar Screen -- preliminary treatment apparatus used to remove large pieces of trash -- sticks, rags, and the like -- from raw wastewater.
DMR (Discharge Monitoring Report) -- report required by the NPDES program that lists a plant's permit limits for wastewater treatment. This report is filled out monthly by a treatment plant, which records observed data, and is sent to ADEM.
Detention Time -- time a theoretical particle/water drop will remain in a tank or basin. The product of capacity divided by flow.
Dissolved Oxygen (DO) -- the amount of free oxygen available in water or other liquid solution for use by bacteria. Measured in ppm (parts per million) or mg/l (milligrams per liter).
Facultative bacteria -- bacteria that function equally well whether free or dissolved oxygen is available in their environment or not.
Force Main -- sewer line fed by a lift station; carries pumped wastewater to a point where other pumps or gravity can take over.
Gravity Sewer -- sewer line that uses a declining grade to induce the flow of wastewater. This is the most common type of sewer line in existence.
Lift Station -- an assembly of a wet well, a level control, and one or more pumps designed to take the flow from a gravity sewer system and boost it over a hill or up some other grade where the installation of gravity sewer lines is impossible or impractical.
MGD (Million Gallons per Day) -- common unit of flow measurement in a wastewater treatment plant. 1,000,000 gallons over a 24-hour period of time.
mg/l (milligrams per liter) -- a measurement of concentration in a solution; i.e. how many milligrams of what is being measured per one liter of solution. Functionally equivalent to ppm.
Mixed Liquor -- term used to describe the mixture of wastewater and activated sludge in a treatment plant.
NPDES -- Acronym for "National Pollutant Discharge Elimination System. Permitting system set up by Federal law in 1972 with the intended purpose of protecting the waters of the United States,
PPM (Parts per Million) -- a measurement of concentration in a solution; i.e. how many "parts" of what is being measured for every one million equivalent "parts" of the solution. Example -- one red sand grain mixed in among 999,999 other white sand grains yields a red sand grain measurement of 1 ppm. Functionally equivalent to mg/l.
Pathogens -- bacteria or other things (virii, et. al) that cause disease in a host.
"Raw" wastewater -- wastewater that has not been treated by any means at all.
Septic -- A condition produced by the presence of anaerobic bacteria. Severe septic conditions are revealed by black, odorous water with little or no dissolved oxygen present.
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