WASTEWATER GRADE 1 TEST PREP
COURSEWORK SCRIPT STUDY SHEET 2026
GRADED A+.
⫸ Methane ch4. Answer: Anaerobic digester have 62-70% methane
vol basis. Lel is 5% and uel is 15%.flammable/ explosive. Odorless,
not toxic but can asphyxiate at high conc, lighter than air.
⫸ Anaerobic digester gas. Answer: 65% methane, 34% carbon
dioxide, 1% other inert gases. Contains less than 1% h2s
⫸ Parshall flume. Answer: Open channel device that constricts the
flow in such away that the depth of flow upstream of the flume is
directly related to the flow rate passing through the flume. Does not
measure velocity.
⫸ Carbon dioxide. Answer: Aerobic bacteria exhale carbon dioxide.
Anaerobic bacteria produce carbon dioxide. Non flammable, odorless,
not toxic but can asphyxiate at high conc, heavier than air.
⫸ Grit. Answer: Sand, coffee grounds, seeds, small pieces of gravel
and metals, eggshells. Removed by velocity controlled grit chambers
or aerated grit chambers. Flow is slowed to 1 f/s
⫸ Objectives of primary treatment. Answer: Remove TSSset and the
BOD associated with TSSset, remove floatable material(scum)
, ⫸ Performance of primary clarifiers. Answer: >95% SS removal, 40-
60% TSS removal, 25-40% BOD removal, detention time 1.5 to 2.5
hrs, weir over flow 10000 to 15000 gal/d ft, hydraulic loading 600 to
1200 gal/d ft2
⫸ Hydraulic loading. Answer: Gal/d ft2 (Surface loading or surface
over flow rate) how many gallons of water per day are passing
through each square foot of clarifier surface area. Performance is
directly related to hydraulic loading .
⫸ Weir overflow rate. Answer: Gal/d ft. Divide flow in gal/ day by
weir length in units of feet.
⫸ Detention time. Answer: Generally 1 hr minimum. If too long(2.5 -
3hrs) then odors may be a problem in a primary clarifier and BOD
removal may be compromised due to solubilization of BOD in the
sludge blanket. Divide vol by influential flow rate.
⫸ Primary clarifier performance. Answer: The BOD and TSS tests
should be run on 24hr, flow weighted primary influent and primary
effluent composite samples. SS test should always be a grab sample.
⫸ Anaerobic digestion. Answer: Stabilization of raw sludge solids is
the key. VS, pathogen, and volume reduction and gas production are
the process objectives.
COURSEWORK SCRIPT STUDY SHEET 2026
GRADED A+.
⫸ Methane ch4. Answer: Anaerobic digester have 62-70% methane
vol basis. Lel is 5% and uel is 15%.flammable/ explosive. Odorless,
not toxic but can asphyxiate at high conc, lighter than air.
⫸ Anaerobic digester gas. Answer: 65% methane, 34% carbon
dioxide, 1% other inert gases. Contains less than 1% h2s
⫸ Parshall flume. Answer: Open channel device that constricts the
flow in such away that the depth of flow upstream of the flume is
directly related to the flow rate passing through the flume. Does not
measure velocity.
⫸ Carbon dioxide. Answer: Aerobic bacteria exhale carbon dioxide.
Anaerobic bacteria produce carbon dioxide. Non flammable, odorless,
not toxic but can asphyxiate at high conc, heavier than air.
⫸ Grit. Answer: Sand, coffee grounds, seeds, small pieces of gravel
and metals, eggshells. Removed by velocity controlled grit chambers
or aerated grit chambers. Flow is slowed to 1 f/s
⫸ Objectives of primary treatment. Answer: Remove TSSset and the
BOD associated with TSSset, remove floatable material(scum)
, ⫸ Performance of primary clarifiers. Answer: >95% SS removal, 40-
60% TSS removal, 25-40% BOD removal, detention time 1.5 to 2.5
hrs, weir over flow 10000 to 15000 gal/d ft, hydraulic loading 600 to
1200 gal/d ft2
⫸ Hydraulic loading. Answer: Gal/d ft2 (Surface loading or surface
over flow rate) how many gallons of water per day are passing
through each square foot of clarifier surface area. Performance is
directly related to hydraulic loading .
⫸ Weir overflow rate. Answer: Gal/d ft. Divide flow in gal/ day by
weir length in units of feet.
⫸ Detention time. Answer: Generally 1 hr minimum. If too long(2.5 -
3hrs) then odors may be a problem in a primary clarifier and BOD
removal may be compromised due to solubilization of BOD in the
sludge blanket. Divide vol by influential flow rate.
⫸ Primary clarifier performance. Answer: The BOD and TSS tests
should be run on 24hr, flow weighted primary influent and primary
effluent composite samples. SS test should always be a grab sample.
⫸ Anaerobic digestion. Answer: Stabilization of raw sludge solids is
the key. VS, pathogen, and volume reduction and gas production are
the process objectives.
