n environment containing no “free” or dissolved oxygen.
Wastewater solids, usually at 5% solids, that are decomposed by bacteria in the absence of dissolved oxygen.
An ionic type of cleaning product that contains a negatively charge surface-active agent.
A sterile or germ free environment.
An abbreviation for the term, Biochemical Oxygen Demand. It is the rate at which microorganisms’ use dissolved oxygen in water or wastewater for the conversion of dissolved organics into cellular material.
A laboratory procedure that measures the rate of oxygen use under controlled conditions of time and temperature.
A mass or clump of living organisms feeding on wastes, dead organisms or debris in wastewater.
Clouds of billowing sludge usually associated with algae or bacteria in secondary clarifiers when the sludge becomes too light to settle properly.
A mechanical device that uses gravitational forces at high speed to separate solids from liquids.
A measure of the rate of oxygen consumption by organic and inorganic compounds in wastewater.
Any process or combination of processes whose major purpose is reducing the concentration of suspended matter in a liquid phase.
Any chemical or substance used to assist coagulation.
The use of chemicals to cause small particles to agglomerate into larger particles, thus making separation of solids from liquid easier.
Very finely divided particles that remain dispersed in a liquid phase for long periods of time due to their electrical charge and small size.
In contact stabilization, which is a modification of the conventional activated sludge process, two (2) aeration tanks are used. One tank is used for separate re-aeration of return sludge, usually for at least four (4) hours, before it flows into the other tank where it is mixed with raw primary wastewater.
A condition in which nitrite or nitrate ions are reduce to nitrogen gas. The resulting bubbles often cause floating sludge in secondary clarifiers or gravity thickeners.
A tank in which sludge is placed to allow decomposition by microorganisms.
A mechanical device which facilitates the separation of solids from the liquid phase be use of super-saturated air to generate floatation bubbles.
Molecular oxygen dissolved in water or wastewater and is usually abbreviates as DO.
Wastewater or other liquid flowing from a tank, process or container.
A holding basin in which variations in flow or concentration are averaged.
Bacteria that can live under aerobic or anaerobic conditions.
The gathering together of finer particles to form larger particles.
GRAS means generally recognized as safe. It is the designation given to substances that are considered safe for direct or indirect additives to foods. For a substance to be considered GRAS it had to meet certain criteria. There are two basic ways for a substance to be designated as GRAS. The criteria for this process is given in detail in the Code of Federal Regulations Title 21, Volume 3, Parts 170.30. The Federal code is searchable from: http://www.gpoaccess.gov/cfr/retrieve.html
Wastewater or other liquid flowing into a tank, container or process.
A laboratory procedure for estimation of the amount of chemical that will be needed to achieve selected water quality standards.
Material Safety Data Sheet – an MSDS provide important product information for proper handling, storage, shipping and other areas that employees dealing with said product should know.
The mixing of activated sludge with raw wastewater and return sludge in an aeration tank. Mixed liquor may also refer to the contents of aerobic and anaerobic digesters.
The suspendedsolids in the mixed liquor of an aeration tank. Comprised of volatile and non-volatile suspended solids.
The organic or volatile suspended solids in the mixed liquor of an aeration tank. Commonly used to indicate viable bacteria content when compared to MLLS.
Organisms that exhibit or are capable of movement.
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