Carbonaceous biochemical oxygen demand (CBOD): A chemical quantitative
measure of the amount of dissolved oxygen required for the biological oxidation
of carbon-containing compounds in a sample.
Chemical oxygen demand (COD): An environmental chemical test used to measure indirectly organic compounds in water or wastewater.
Chlorination: One of the disinfection processes involving the use of chlorine gas.
Disinfection with chlorine is accomplished by adding chlorine gas to the water or
wastewater. Sometimes application of sodium hypochlorite (liquid) for disinfection is also called chlorination. Academically disinfection using sodium hypochlorite should be called hypochlorination.
Clari-DAF: It is rectangular dissolved air flotation (DAF) clarifier commercially
available from Xylem Water and Wastewater, Zelienople, PA 16063, USA.
Comminuting: It is a grinding or shredding operation for reducing the particle size
of objects or debris in the influent wastewater. They are installed with a screen
directly in the influent wastewater flow’s channel, with the shredded particles
returned to the flow downstream of the screen. The influent flow is channeled to
and through these units. The debris is collected against the screen, or outside
drum, and the teeth which penetrate this screen cut up the solids. When the solids
are reduced to the size of the screen or drum openings, they pass through and on
for additional downstream wastewater treatment. The barminutor is a comminuting device that incorporates revolving cutters that move up and down the
upstream face of a bar screen, shredding and cutting whatever debris has accumulated against the screen. The screenings are transported to the cutting device,
shredded, and then allowed to fall back into the influent channel downstream of
the bar screen.
Complete mix activated sludge process: It is an activated process in which
aeration tank (with about 3–5 hours DT) is usually circular and the influent
wastewater and the mixed liquor are completely mixed during aeration operation.
It is most useful for treating wastewater with fluctuating organic strength because
it is least susceptible to shock loads among all activated sludge processes. A
mechanically stirred reactor best simulates a complete mix condition. When
diffused aeration in a rectangular aeration tank is used, the mixture of wastewater
influent and the return sludge should enter the aeration tank at several points in a
central location with the effluent going into channels on the sides of the
aeration tank.
Contact stabilization process: It is a modification of the activated sludge process.
In this modification, the adsorptive capacity of the floc is utilized in the contact
tank to adsorb suspended, colloidal, and some dissolved organics. The hydraulic
detention time in the contact tank is only about 30–60 minutes (based on average
daily flow). After the biological sludge is separated from the wastewater in the
secondary clarifier (either secondary sedimentation clarifier or secondary flotation
clarifier), the concentrated sludge is separately aerated in the stabilization tank
with a detention time of 2–6 hours (based on sludge recycle flow). The adsorbed
organics undergo oxidation in the stabilization tank and are synthesized into
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L. K. Wang et al.
measure of the amount of dissolved oxygen required for the biological oxidation
of carbon-containing compounds in a sample.
Chemical oxygen demand (COD): An environmental chemical test used to measure indirectly organic compounds in water or wastewater.
Chlorination: One of the disinfection processes involving the use of chlorine gas.
Disinfection with chlorine is accomplished by adding chlorine gas to the water or
wastewater. Sometimes application of sodium hypochlorite (liquid) for disinfection is also called chlorination. Academically disinfection using sodium hypochlorite should be called hypochlorination.
Clari-DAF: It is rectangular dissolved air flotation (DAF) clarifier commercially
available from Xylem Water and Wastewater, Zelienople, PA 16063, USA.
Comminuting: It is a grinding or shredding operation for reducing the particle size
of objects or debris in the influent wastewater. They are installed with a screen
directly in the influent wastewater flow’s channel, with the shredded particles
returned to the flow downstream of the screen. The influent flow is channeled to
and through these units. The debris is collected against the screen, or outside
drum, and the teeth which penetrate this screen cut up the solids. When the solids
are reduced to the size of the screen or drum openings, they pass through and on
for additional downstream wastewater treatment. The barminutor is a comminuting device that incorporates revolving cutters that move up and down the
upstream face of a bar screen, shredding and cutting whatever debris has accumulated against the screen. The screenings are transported to the cutting device,
shredded, and then allowed to fall back into the influent channel downstream of
the bar screen.
Complete mix activated sludge process: It is an activated process in which
aeration tank (with about 3–5 hours DT) is usually circular and the influent
wastewater and the mixed liquor are completely mixed during aeration operation.
It is most useful for treating wastewater with fluctuating organic strength because
it is least susceptible to shock loads among all activated sludge processes. A
mechanically stirred reactor best simulates a complete mix condition. When
diffused aeration in a rectangular aeration tank is used, the mixture of wastewater
influent and the return sludge should enter the aeration tank at several points in a
central location with the effluent going into channels on the sides of the
aeration tank.
Contact stabilization process: It is a modification of the activated sludge process.
In this modification, the adsorptive capacity of the floc is utilized in the contact
tank to adsorb suspended, colloidal, and some dissolved organics. The hydraulic
detention time in the contact tank is only about 30–60 minutes (based on average
daily flow). After the biological sludge is separated from the wastewater in the
secondary clarifier (either secondary sedimentation clarifier or secondary flotation
clarifier), the concentrated sludge is separately aerated in the stabilization tank
with a detention time of 2–6 hours (based on sludge recycle flow). The adsorbed
organics undergo oxidation in the stabilization tank and are synthesized into
142
L. K. Wang et al.