WASTEWATER OPERATOR CLASS 3
PRACTICE TRAINING REVIEW SCRIPT 2026
FULL ANSWERS GRADED A+
⩥ Settleable solids (SS)
Answer: suspended solids, heavy enough to settle.
⩥ settleable solids test
Answer: use one liter of solids from end of AB, to represent what is
going into the clarifier, and let suspended solids settle over 30 minute or
1 hour time.
Milliliters of solids equals gallons of sludge for each 1000 gallons of
wastewater. This is equal to 1000 gallons of sludge per million gallons
of wastewater.
⩥ Inorganic solids (ash)
Answer: suspended or dissolved, include sand, grit, and minerals (such
as chlorides, sulfates, nitrates, metals, etc.)
The ash that remains after a sample goes through a muffle furnace is
representative of the inorganic or fixed solids.
⩥ Organic solids (volatiles)
,Answer: material that comes from plants, animals and humans, living or
once living. Consists of carbohydrates, proteins, and greases.
⩥ carbohydrates
Answer: decompose first due to simplicity. Decay by aerobic bacteria
produces CO2 and water. Anaerobic decay produces hydrogen sulfide,
ammonia, methane, CO2 or organic acids.
⩥ Protein
Answer: Slow to decompose due to complexity. Protein aerobically
decays into nitrates, CO2, and water.
Anaerobically decomposes into ammonia and methane.
Fecal matter is 85% protein
Urine is 35% protein
⩥ saponifiable Grease
Answer: organic and slowly stabilizes. EX is soap. Bacterial
decomposition of organic grease produces CO2, water and methane.
⩥ Non-saponifiable grease
Answer: Inorganic grease. It cannot make soap and is harmful to
bacteria.
⩥ Relationship between DO, Temp and pressure
, Answer: DO goes up; temp and pressure go down.
DO goes down; temp and pressure go up
⩥ oxygen demand
Answer: A measure of oxidizable material in the water. DOB and COD
⩥ BOD (Biological Oxygen Demand)
Answer: Wastewater strength. Measures the oxygen consumed as
organics are oxidized biologically and chemically during 5 days of
incubation at 20C (68F). can determine treatment efficiency.
⩥ Raw WW typically has a BOD of
Answer: 100 to 300 mg/L
⩥ COD (Chemical Oxygen Demand)
Answer: A measure of the oxygen-consuming capacity of organic matter
present in wastewater.
⩥ pH
Answer: Potential hydrogen ion concentration.
Measuring free H+ concentration in solution being measured.
PRACTICE TRAINING REVIEW SCRIPT 2026
FULL ANSWERS GRADED A+
⩥ Settleable solids (SS)
Answer: suspended solids, heavy enough to settle.
⩥ settleable solids test
Answer: use one liter of solids from end of AB, to represent what is
going into the clarifier, and let suspended solids settle over 30 minute or
1 hour time.
Milliliters of solids equals gallons of sludge for each 1000 gallons of
wastewater. This is equal to 1000 gallons of sludge per million gallons
of wastewater.
⩥ Inorganic solids (ash)
Answer: suspended or dissolved, include sand, grit, and minerals (such
as chlorides, sulfates, nitrates, metals, etc.)
The ash that remains after a sample goes through a muffle furnace is
representative of the inorganic or fixed solids.
⩥ Organic solids (volatiles)
,Answer: material that comes from plants, animals and humans, living or
once living. Consists of carbohydrates, proteins, and greases.
⩥ carbohydrates
Answer: decompose first due to simplicity. Decay by aerobic bacteria
produces CO2 and water. Anaerobic decay produces hydrogen sulfide,
ammonia, methane, CO2 or organic acids.
⩥ Protein
Answer: Slow to decompose due to complexity. Protein aerobically
decays into nitrates, CO2, and water.
Anaerobically decomposes into ammonia and methane.
Fecal matter is 85% protein
Urine is 35% protein
⩥ saponifiable Grease
Answer: organic and slowly stabilizes. EX is soap. Bacterial
decomposition of organic grease produces CO2, water and methane.
⩥ Non-saponifiable grease
Answer: Inorganic grease. It cannot make soap and is harmful to
bacteria.
⩥ Relationship between DO, Temp and pressure
, Answer: DO goes up; temp and pressure go down.
DO goes down; temp and pressure go up
⩥ oxygen demand
Answer: A measure of oxidizable material in the water. DOB and COD
⩥ BOD (Biological Oxygen Demand)
Answer: Wastewater strength. Measures the oxygen consumed as
organics are oxidized biologically and chemically during 5 days of
incubation at 20C (68F). can determine treatment efficiency.
⩥ Raw WW typically has a BOD of
Answer: 100 to 300 mg/L
⩥ COD (Chemical Oxygen Demand)
Answer: A measure of the oxygen-consuming capacity of organic matter
present in wastewater.
⩥ pH
Answer: Potential hydrogen ion concentration.
Measuring free H+ concentration in solution being measured.
