Definitions Flashcards
Activated Sludge Process
A wastewater treatment process that speeds up the decomposition of wasted in the wastewater being treated. Activated Sludge is added to wastewater and the mixture (mixed liquor) is aerated and agitated. After some time in the aeration tank, the activated sludge is allowed to settle out by sedimentation and is disposed of (wasted) or reused (returned to the aeration tank) as needed. The remaining wastewater then undergoes more treatment.
Aeration Tank
The tank where raw or settled wastewater is mixed with return sludge and aerated. The same as aeration bay, aerator, or reactor.
Aerobic Bacteria
Bacteria that will live and reproduce only in an environment containing oxygen that is available for their respiration(breathing), namely atmospheric oxygen or oxygen dissolved in water. Oxygen combined chemically, such as in water molecules cannot be used for respiration by aerobic bacteria.
Algae
Microscopic plants containing chlorophyll that live floating or suspended in water. They may also be attached to structures, rocks, or other submerged surfaces. Excess algal growths can impart tastes and odors to potable water. Algae produce oxygen during sunlight hours and use oxygen during the night hours. Their biological activities appreciably affect the PH, alkalinity and DO of the water.
Anaerobic Bacteria
Bacteria that live and reproduce in an environment containing no free or dissolved oxygen. Anaerobic bacteria obtain their oxygen supply by breaking down chemical compounds that contain oxygen, such as sulfate (SO42-)
BOD
Biochemical Oxygen Demand. The rate at which organisms use the oxygen in water or wastewater while stabilizing decompostable organic matter under aerobic conditions. In decomposition, organic matter served as food for the bacteria and energy results from its oxidation. BOD measurements are used as a surrogate measure of the organic strength of wastes in water.
Biomass
A mass or clump of organic material consisting of living organisms feeding on the wastes in wastewater, dead organisms, ad other debris. Also see ZOOGEAL MASS.
Coliform
A group of bacteria found in the intestines of warm blooded animals (including humans) and alps in plants, soil, air and water. The presence of coliform bacteria is an indication that the water is polluted and may contain pathogenic organisms. Fecal coliforms are those coliforms found in the feces of warm-blooded animals, whereas the term coliform also includes other environmental sources.
Comminution
A mechanical treatment process that cuts large pieces of wastes into smaller pieces so they will not plug pipes or damage equipment. Comminution and shredding usually mean the same thing.
Decomposition or Decay
The conversion of chemically unstable materials to more stable forms by chemical or biological action.
Detention Time
The time required to fill a tank at a given flow or the theoretical time required for a given flow of wastewater to pass through a tank. In septic tanks, this detention time will decrease as volumes of sludge or scum increases.
Dewater
1) To remove or separate a portion of the water present in a sludge or slurry. To dry sludge so it can be handled and disposed of.
2) To remove or drain the water from a tank or a trench. A structure may be dewatered so that it can be inspected or repaired.
Disinfection
The process designed to kill or inactivate most microorganisms in water or wastewater, including essentially all pathogenic bacteria. There are several ways to disinfect, with chlorination being the most frequently used in water and wastewater treatment plants. Compare with STERILIZATION.
Effluent
Water or other liquid - raw(untreated), partially treated, or completely treated - flowing from a reservoir, basin, treatment process or treatment plant.
Entrain
To trap bubbles in water, either mechanically through turbulence or chemically through a reaction.
