Acinetobacter A common heterotrophic bacteria that functions as a phosphorusaccumulating organism (PAO) in biological phosphorus removal process.
Activated carbon adsorption, granular Granular activated carbon (GAC) is used
in both water and wastewater treatment. GAC systems generally consist of
vessels in which the carbon is placed, forming a “filter” bed. These systems can
also include carbon storage vessels and thermal regeneration facilities. Vessels
are usually circular for pressure systems or rectangular for gravity flow systems.
Once the carbon adsorptive capacity has been fully utilized, it must be disposed of
or regenerated. Usually multiple carbon vessels are used to allow continuous
operation. Columns can be operated in series or parallel modes. All vessels must
be equipped with carbon removal and loading mechanisms to allow for the
removal of spent carbon and the addition of new material. Flow can be either
upward or downward through the carbon bed. Vessels are backwashed periodically. Surface wash and air scour systems can also be used as part of the backwash
cycle. Small systems usually dispose of spent carbon or regenerate it offsite.
Systems above about 3 to 5 MGD (million gallons per day) usually provide
on-site regeneration of carbon for economic reasons.
Activated carbon adsorption, powdered Powdered activated carbon (PAC) is
used in both water and wastewater treatment. For water treatment, PAC systems
generally involve dosing powdered activated carbons in slurry form to rapid
mixers and flocculators (for mixing and flocculation, and adsorption) before
reaching clarifiers for PAC-floc separation and clarifier effluent discharge. For
wastewater treatment, powdered activated carbon in slurry form is dosed to either
mixing/flocculation chambers (if they exist), or to an aeration basin directly to be
mixed with mixed liquor for adsorption reactions. The spent PAC again is
recovered or removed by a subsequent clarifier (either sedimentation clarifier or
flotation clarifier). When PAC is used in conjunction with a flotation clarifier, it is
also called “adsorption flotation.”
Activated carbon It is a porous carbon adsorbent with many micropores,
microchannels, and high surface area for adsorption (removal) of mainly soluble
organic substances, color, odor, and some inorganic heavy metals from water or
air. There are three kinds of activated carbons: (a) powdered activated carbon;
(b) granular activated carbon; and (c) cloth or fiber-type activated carbon.
Activated sludge They are sludge particles produced in raw or settled wastewater
(primarily effluent) by the growth of organisms (including zoogleal bacteria) in
aeration tanks in the presence of dissolved oxygen. The term “activated” comes
from the fact that the particles are teeming with bacteria, fungi, and protozoa.
Activated sludge is different from primary sludge in that the sludge particles
contain many living organisms, which can feed on the incoming wastewater.
Activated sludge process (a) It is a continuous flow, biological treatment process
characterized by a suspension of aerobic microorganisms, maintained in a relatively homogeneous state by the mixing and turbulence induced by aeration. The
microorganisms are used to oxidize soluble and colloidal organics to carbon
dioxide and water in the presence of molecular oxygen. The process is generally,
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Activated carbon adsorption, granular Granular activated carbon (GAC) is used
in both water and wastewater treatment. GAC systems generally consist of
vessels in which the carbon is placed, forming a “filter” bed. These systems can
also include carbon storage vessels and thermal regeneration facilities. Vessels
are usually circular for pressure systems or rectangular for gravity flow systems.
Once the carbon adsorptive capacity has been fully utilized, it must be disposed of
or regenerated. Usually multiple carbon vessels are used to allow continuous
operation. Columns can be operated in series or parallel modes. All vessels must
be equipped with carbon removal and loading mechanisms to allow for the
removal of spent carbon and the addition of new material. Flow can be either
upward or downward through the carbon bed. Vessels are backwashed periodically. Surface wash and air scour systems can also be used as part of the backwash
cycle. Small systems usually dispose of spent carbon or regenerate it offsite.
Systems above about 3 to 5 MGD (million gallons per day) usually provide
on-site regeneration of carbon for economic reasons.
Activated carbon adsorption, powdered Powdered activated carbon (PAC) is
used in both water and wastewater treatment. For water treatment, PAC systems
generally involve dosing powdered activated carbons in slurry form to rapid
mixers and flocculators (for mixing and flocculation, and adsorption) before
reaching clarifiers for PAC-floc separation and clarifier effluent discharge. For
wastewater treatment, powdered activated carbon in slurry form is dosed to either
mixing/flocculation chambers (if they exist), or to an aeration basin directly to be
mixed with mixed liquor for adsorption reactions. The spent PAC again is
recovered or removed by a subsequent clarifier (either sedimentation clarifier or
flotation clarifier). When PAC is used in conjunction with a flotation clarifier, it is
also called “adsorption flotation.”
Activated carbon It is a porous carbon adsorbent with many micropores,
microchannels, and high surface area for adsorption (removal) of mainly soluble
organic substances, color, odor, and some inorganic heavy metals from water or
air. There are three kinds of activated carbons: (a) powdered activated carbon;
(b) granular activated carbon; and (c) cloth or fiber-type activated carbon.
Activated sludge They are sludge particles produced in raw or settled wastewater
(primarily effluent) by the growth of organisms (including zoogleal bacteria) in
aeration tanks in the presence of dissolved oxygen. The term “activated” comes
from the fact that the particles are teeming with bacteria, fungi, and protozoa.
Activated sludge is different from primary sludge in that the sludge particles
contain many living organisms, which can feed on the incoming wastewater.
Activated sludge process (a) It is a continuous flow, biological treatment process
characterized by a suspension of aerobic microorganisms, maintained in a relatively homogeneous state by the mixing and turbulence induced by aeration. The
microorganisms are used to oxidize soluble and colloidal organics to carbon
dioxide and water in the presence of molecular oxygen. The process is generally,
424
M.-H. S. Wang and L. K. Wang