sludge dewatering. The process reduces volatile solids and thereby reduces the
overall mass of the sludge, lowering subsequent land disposal costs.
Anaerobic: An environmental condition in which free, dissolved, and combined
oxygen is unavailable in an aqueous environment.
Anoxic: A environmental condition in which oxygen is almost only available in a
combined form, such as nitrate (NO 3 ), nitrite (NO 2 ), or sulfate (SO 4 ), in an
aqueous environment. Dissolved oxygen (DO) concentration is in the range of
0 to 0.1 mg/L.
AquaDAF: It is a rectangular dissolved air flotation (DAF) clarifier commercially
available from SUEZ Water Technologies and Solutions, Richmond, VA 23229,
USA.
Assimilation: The biological or microbiological process in which nitrogen is taken
in by cells to be used for growth and reproduction.
Attached-growth biological processes: In an attached-growth biological process
system, the biomass responsible for biochemical reactions are attached on the
surface of rocks, sands, woods, disks, screens, etc. where the wastewater pass
through, and the organic pollutants and nutrients are removed. They include
trickling filters, denitrification filter using coarse media, denitrification filter
using fine media, slow sand filters, rotating biological contactors, etc. The effluent
from an attached-growth bioreactor discharges to a water-solid separator (sedimentation clarifier, or flotation clarifier, or membrane filter) for further
processing.
Autotrophic organisms: Organisms that use carbon dioxide, sunlight, or other
inorganic substances for their cell growth (nitrifying bacteria are autotrophic).
Bar screens: There are two types of bar screens (or racks). The most commonly
used, and oldest technology, consists of hand-cleaned bar racks. These are
generally used in smaller wastewater treatment plants (WWP). The second type
of bar screen is the type that is mechanically cleaned, which is commonly used in
larger facilities.
Biochemical oxygen demand (BOD): A biochemical quantitative measure of the
amount of oxygen used in the biochemical oxidation of organic matter in a
specified time period (usually 5 days), at a specified temperature (usually
20
C), and under specified conditions (in the dark).
Biological nutrient removal (BNR): The removal of nitrogen and/or phosphorus
by the use of proliferation and selection of certain microbiological populations.
Biological phosphorus removal (BPR): The biological process of phosphorus
removal in wastewater that relies on the proliferation and selection of a microbiological population capable of storing phosphorus in excess of their normal
growth requirements. Also called biological nutrient removal (BNR) or enhanced
biological phosphorus removal (EBPR).
Biosolids: It is a general term for any organic solids containing carbon, such as
activated sludge, septic tank sludge, manure, etc.
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141
overall mass of the sludge, lowering subsequent land disposal costs.
Anaerobic: An environmental condition in which free, dissolved, and combined
oxygen is unavailable in an aqueous environment.
Anoxic: A environmental condition in which oxygen is almost only available in a
combined form, such as nitrate (NO 3 ), nitrite (NO 2 ), or sulfate (SO 4 ), in an
aqueous environment. Dissolved oxygen (DO) concentration is in the range of
0 to 0.1 mg/L.
AquaDAF: It is a rectangular dissolved air flotation (DAF) clarifier commercially
available from SUEZ Water Technologies and Solutions, Richmond, VA 23229,
USA.
Assimilation: The biological or microbiological process in which nitrogen is taken
in by cells to be used for growth and reproduction.
Attached-growth biological processes: In an attached-growth biological process
system, the biomass responsible for biochemical reactions are attached on the
surface of rocks, sands, woods, disks, screens, etc. where the wastewater pass
through, and the organic pollutants and nutrients are removed. They include
trickling filters, denitrification filter using coarse media, denitrification filter
using fine media, slow sand filters, rotating biological contactors, etc. The effluent
from an attached-growth bioreactor discharges to a water-solid separator (sedimentation clarifier, or flotation clarifier, or membrane filter) for further
processing.
Autotrophic organisms: Organisms that use carbon dioxide, sunlight, or other
inorganic substances for their cell growth (nitrifying bacteria are autotrophic).
Bar screens: There are two types of bar screens (or racks). The most commonly
used, and oldest technology, consists of hand-cleaned bar racks. These are
generally used in smaller wastewater treatment plants (WWP). The second type
of bar screen is the type that is mechanically cleaned, which is commonly used in
larger facilities.
Biochemical oxygen demand (BOD): A biochemical quantitative measure of the
amount of oxygen used in the biochemical oxidation of organic matter in a
specified time period (usually 5 days), at a specified temperature (usually
20
C), and under specified conditions (in the dark).
Biological nutrient removal (BNR): The removal of nitrogen and/or phosphorus
by the use of proliferation and selection of certain microbiological populations.
Biological phosphorus removal (BPR): The biological process of phosphorus
removal in wastewater that relies on the proliferation and selection of a microbiological population capable of storing phosphorus in excess of their normal
growth requirements. Also called biological nutrient removal (BNR) or enhanced
biological phosphorus removal (EBPR).
Biosolids: It is a general term for any organic solids containing carbon, such as
activated sludge, septic tank sludge, manure, etc.
3 Biological Processes
141