Evaporation The process by which water changes from a liquid to a gas or vapor.
Evapotranspiration (a) The combined process of evaporation from the Earth’s
surface and transpiration from vegetation. (b) The process by which water vapor
passes into the atmosphere from living plants, also called transpiration. (c) The
total water removed from an area by transpiration (living plants) and by evaporation from soil, snow, and water surfaces.
Excessive heat When heat index values meet or exceed daytime highs of
105–110
F (depending on local climate).
Excreta It is a waste matter discharged from the body, especially feces and urine.
Exercise A way to train for, assess, practice, and improve performance in prevention, protection, response, and recovery capabilities in a risk-free environment.
Exercises can be used for testing and validating policies, plans, procedures,
training, equipment, and interagency agreements; clarifying and training personnel in roles and responsibilities; improving interagency coordination and communications; identifying gaps in resources; improving individual performance;
and identifying opportunities for improvement.
Extended aeration activated sludge process A long aeration time (over 18 hours
DT) is employed in an extended aeration system. It is applicable only to small
wastewater treatment plants of less than 3785 m
3 /day or 1.0 MGD. Normally, no
primary clarifier is provided and no exercise of optimum return sludge control is
attempted although the return activated sludge (RAS) flow is about 75% to 100%
of plant flow. The objective is to simplify the process both in construction and in
operation. Sludge production is very small because of prolonged endogenous
oxidation, which minimizes the problem of sludge treatment and disposal. The
aeration effluent’s sludge normally has an inferior settling characteristic. Therefore, a secondary flotation clarifier is better for an extended aeration plant.
Fallow It is an area (of farmland) plowed and harrowed but left unsown for a period
in order to restore its fertility as part of a crop rotation or to avoid surplus
production
F-Cell Dissolved air flotation cell or DAF.
Feedback mechanisms Factors that increase or amplify (positive feedback) or
decrease (negative feedback) the rate of a process. An example of positive
climatic feedback is the ice-albedo feedback.
FEMA The Federal Emergency Management Agency is the USA’s lead emergency
management and preparedness agency.
Fermentation The process in which bacteria degrade organic matter under anaerobic conditions, such as in a collection system, primary clarifier, anaerobic
selector, or fermenter tank
FF-Cell Dissolved air flotation and filtration cell or DAFF.
Field margins It is generally the least productive areas of a field and just a 1-metre
grass strip between the outer edge of the hedges, and the crop edge can benefit
wildlife in many ways.
Filamentous organism (a) Microorganisms, such as bacterial, algal, or fungal
species, that grow in thread-like colonies, or a biological mass that may interfere
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449
Evapotranspiration (a) The combined process of evaporation from the Earth’s
surface and transpiration from vegetation. (b) The process by which water vapor
passes into the atmosphere from living plants, also called transpiration. (c) The
total water removed from an area by transpiration (living plants) and by evaporation from soil, snow, and water surfaces.
Excessive heat When heat index values meet or exceed daytime highs of
105–110
F (depending on local climate).
Excreta It is a waste matter discharged from the body, especially feces and urine.
Exercise A way to train for, assess, practice, and improve performance in prevention, protection, response, and recovery capabilities in a risk-free environment.
Exercises can be used for testing and validating policies, plans, procedures,
training, equipment, and interagency agreements; clarifying and training personnel in roles and responsibilities; improving interagency coordination and communications; identifying gaps in resources; improving individual performance;
and identifying opportunities for improvement.
Extended aeration activated sludge process A long aeration time (over 18 hours
DT) is employed in an extended aeration system. It is applicable only to small
wastewater treatment plants of less than 3785 m
3 /day or 1.0 MGD. Normally, no
primary clarifier is provided and no exercise of optimum return sludge control is
attempted although the return activated sludge (RAS) flow is about 75% to 100%
of plant flow. The objective is to simplify the process both in construction and in
operation. Sludge production is very small because of prolonged endogenous
oxidation, which minimizes the problem of sludge treatment and disposal. The
aeration effluent’s sludge normally has an inferior settling characteristic. Therefore, a secondary flotation clarifier is better for an extended aeration plant.
Fallow It is an area (of farmland) plowed and harrowed but left unsown for a period
in order to restore its fertility as part of a crop rotation or to avoid surplus
production
F-Cell Dissolved air flotation cell or DAF.
Feedback mechanisms Factors that increase or amplify (positive feedback) or
decrease (negative feedback) the rate of a process. An example of positive
climatic feedback is the ice-albedo feedback.
FEMA The Federal Emergency Management Agency is the USA’s lead emergency
management and preparedness agency.
Fermentation The process in which bacteria degrade organic matter under anaerobic conditions, such as in a collection system, primary clarifier, anaerobic
selector, or fermenter tank
FF-Cell Dissolved air flotation and filtration cell or DAFF.
Field margins It is generally the least productive areas of a field and just a 1-metre
grass strip between the outer edge of the hedges, and the crop edge can benefit
wildlife in many ways.
Filamentous organism (a) Microorganisms, such as bacterial, algal, or fungal
species, that grow in thread-like colonies, or a biological mass that may interfere
12 Glossary of Natural Resources and Environmental Pollution Control
449