(b) high rate digestion mode: one stage, heated, and mixed; (c) two-stage digestion mode; and (d) anaerobic contact process. Anaerobic digestion can occur in
two temperature ranges: mesophilic (80–110
F) and thermophilic (113–149
F).
Mesophilic range operation is more stable, while thermophilic range operation
offers improved sludge dewatering. The process reduces volatile solids and
thereby reduces the overall mass of the sludge, lowering subsequent land disposal
costs. Wastewater solids and water (about 5% solids, 95% water) are placed in a
large tank where bacteria decompose the solids in the absence of dissolved
oxygen.
Analysis (chemical) The determination of the qualitative and/or quantitative composition of a substance.
Analytical reagent (AR) The American Chemical Society’s designation for the
highest purity of certain chemical reagents and solvents.
Anchor booms They are parts fitted on some dredges for handling and placing the
swing anchors from the dredge without the need of a support vessel, or mounted
at the bow and suspended from a gantry or gallows frame.
Anionic polymer (or anionic polyelectrolyte) A negatively charged electrolyte
used as a coagulant to aid in separating (settling or floating) solids in water or
wastewater.
Anionic surfactant A negatively charged surface active agent, such as ABS and
LAS, that lowers the surface tension in water, and usually used as a cleaning
agent, or as a collector in a flotation process system.
Annual plant It is a plant that completes its life cycle from germination to the
production of seed within one year and then dies.
Anoxic (a) An environmental condition in which oxygen is only available in a
combined form, such as nitrate (NO 3 ), nitrite (NO 2 ), or sulfate (SO 4 ) in an
aqueous environment; (b) oxygen deficient or lacking sufficient oxygen, and
dissolved oxygen ¼ 0.0 to 0.1 mg/L.
Anthropogenic Made by people or resulting from human activities. Usually used in
the context of emissions that are produced as a result of human activities.
Apiary It is a bee year or area when/where colonies, hives, and other equipment
assembled in one location for beekeeping operations, also known as a bee yard.
Apiculture It is a career, or business, or hobby of beekeeping; the keeping of bees,
particularly on a commercial scale.
Approach The difference in temperatures of water temperature exiting the tower
versus the dry bulb temperature of the air entering the tower.
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.
Atmosphere The gaseous envelope surrounding the Earth. The dry atmosphere
consists almost entirely of nitrogen (78.1% volume mixing ratio) and oxygen
(20.9% volume mixing ratio), together with a number of trace gases, such as
428
M.-H. S. Wang and L. K. Wang
two temperature ranges: mesophilic (80–110
F) and thermophilic (113–149
F).
Mesophilic range operation is more stable, while thermophilic range operation
offers improved sludge dewatering. The process reduces volatile solids and
thereby reduces the overall mass of the sludge, lowering subsequent land disposal
costs. Wastewater solids and water (about 5% solids, 95% water) are placed in a
large tank where bacteria decompose the solids in the absence of dissolved
oxygen.
Analysis (chemical) The determination of the qualitative and/or quantitative composition of a substance.
Analytical reagent (AR) The American Chemical Society’s designation for the
highest purity of certain chemical reagents and solvents.
Anchor booms They are parts fitted on some dredges for handling and placing the
swing anchors from the dredge without the need of a support vessel, or mounted
at the bow and suspended from a gantry or gallows frame.
Anionic polymer (or anionic polyelectrolyte) A negatively charged electrolyte
used as a coagulant to aid in separating (settling or floating) solids in water or
wastewater.
Anionic surfactant A negatively charged surface active agent, such as ABS and
LAS, that lowers the surface tension in water, and usually used as a cleaning
agent, or as a collector in a flotation process system.
Annual plant It is a plant that completes its life cycle from germination to the
production of seed within one year and then dies.
Anoxic (a) An environmental condition in which oxygen is only available in a
combined form, such as nitrate (NO 3 ), nitrite (NO 2 ), or sulfate (SO 4 ) in an
aqueous environment; (b) oxygen deficient or lacking sufficient oxygen, and
dissolved oxygen ¼ 0.0 to 0.1 mg/L.
Anthropogenic Made by people or resulting from human activities. Usually used in
the context of emissions that are produced as a result of human activities.
Apiary It is a bee year or area when/where colonies, hives, and other equipment
assembled in one location for beekeeping operations, also known as a bee yard.
Apiculture It is a career, or business, or hobby of beekeeping; the keeping of bees,
particularly on a commercial scale.
Approach The difference in temperatures of water temperature exiting the tower
versus the dry bulb temperature of the air entering the tower.
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.
Atmosphere The gaseous envelope surrounding the Earth. The dry atmosphere
consists almost entirely of nitrogen (78.1% volume mixing ratio) and oxygen
(20.9% volume mixing ratio), together with a number of trace gases, such as
428
M.-H. S. Wang and L. K. Wang