CWEA Environmental Compliance
Inspector Grade 1
1. Floatable solids are easy to measure.
Answer: False
2. Barminutors and comminutors are installed for different purposes.
Answer: False
3. The principal difference between step-feed aeration and conventional aeration is
that in step-feed aeration the incoming waste load is introduced in slugs at the tank
entrance.
Answer: False
Fill in the Blank
1. A well-operated digester receives sludge at about 70-75% volatile solids and reduces it
to about 25-30%.
2. The population equivalent factor for BOD is 0.17 lb/day/BOD/person.
3. The fusible plug in chlorine containers should never be removed or tampered with.
4. Application for NPDES renewal must be submitted 180 days before expiry.
5. Typical detention time in a mesophilic digester is 28 days.
6. Mesophilic temperature range is 80 to 100°F.
7. Chlorine applied minus chlorine demand equals chlorine residual.
Multiple Choice (Selected Correct Answers Only)
• Lowest safe O₂ concentration (OSHA):
19.5%
• Microorganisms in good settling mixed liquor:
Rotifers, stalked ciliates, and free-swimming ciliates
• Most stringent heavy metal for land application:
Mercury
• Velocity for grit chamber design:
0.5 to 1.0 ft/sec
• Purpose of sodium thiosulfate in fecal coliform bottles:
Remove chlorine residual
• Wastewater type where settling occurs rapidly:
Strong wastewater
• Disadvantage of constant % RAS flow control:
Max solids loading on clarifier
, • Increase sludge wasting if:
Dark brown scummy foam appears
• Chlorinator ventilation outlet location:
Near the floor
• If pump packing not maintained:
Loss of suction from air entering
• Cause of turbidity in wastewater:
Finely divided suspended material
• Why exclude air from digester:
Avoid explosive mixture
• End products of aerobic reactions:
H₂O and CO₂
• Pump maintenance includes:
All of the above
• Pump packing should be:
Tightened down to a drip
• Pump for primary sludge:
Piston or diaphragm pump
• Pump not damaged by closed discharge valve:
Centrifugal pump
• Chemical to adjust pH to 8.4 for nitrification in RBC:
Soda ash
• Adding acids to chlorine causes:
Chlorine gas release
• Flow treatment before primary tank to remove grease:
Preaerate
• Waterborne diseases:
Typhoid, dysentery, cholera
• Oxygen depletion in water from waste caused by:
Bacteria
• Sludge wasting controls:
Aerator mixed liquor solids
• Safest sludge for soil conditioning:
Heat dried sludge
• Purpose of inlet baffle in settling tank:
Reduce velocity and disperse flow
• Purpose of forced draft ventilation in lift station:
Remove dangerous gases
• High-rate anaerobic digestion implies high:
Volumetric loading
• “Sour” digester conditions:
All of the above
• Volatile solids in sludge measure:
Food for bacteria
• White foam on aeration tank:
Underloaded organically
Inspector Grade 1
1. Floatable solids are easy to measure.
Answer: False
2. Barminutors and comminutors are installed for different purposes.
Answer: False
3. The principal difference between step-feed aeration and conventional aeration is
that in step-feed aeration the incoming waste load is introduced in slugs at the tank
entrance.
Answer: False
Fill in the Blank
1. A well-operated digester receives sludge at about 70-75% volatile solids and reduces it
to about 25-30%.
2. The population equivalent factor for BOD is 0.17 lb/day/BOD/person.
3. The fusible plug in chlorine containers should never be removed or tampered with.
4. Application for NPDES renewal must be submitted 180 days before expiry.
5. Typical detention time in a mesophilic digester is 28 days.
6. Mesophilic temperature range is 80 to 100°F.
7. Chlorine applied minus chlorine demand equals chlorine residual.
Multiple Choice (Selected Correct Answers Only)
• Lowest safe O₂ concentration (OSHA):
19.5%
• Microorganisms in good settling mixed liquor:
Rotifers, stalked ciliates, and free-swimming ciliates
• Most stringent heavy metal for land application:
Mercury
• Velocity for grit chamber design:
0.5 to 1.0 ft/sec
• Purpose of sodium thiosulfate in fecal coliform bottles:
Remove chlorine residual
• Wastewater type where settling occurs rapidly:
Strong wastewater
• Disadvantage of constant % RAS flow control:
Max solids loading on clarifier
, • Increase sludge wasting if:
Dark brown scummy foam appears
• Chlorinator ventilation outlet location:
Near the floor
• If pump packing not maintained:
Loss of suction from air entering
• Cause of turbidity in wastewater:
Finely divided suspended material
• Why exclude air from digester:
Avoid explosive mixture
• End products of aerobic reactions:
H₂O and CO₂
• Pump maintenance includes:
All of the above
• Pump packing should be:
Tightened down to a drip
• Pump for primary sludge:
Piston or diaphragm pump
• Pump not damaged by closed discharge valve:
Centrifugal pump
• Chemical to adjust pH to 8.4 for nitrification in RBC:
Soda ash
• Adding acids to chlorine causes:
Chlorine gas release
• Flow treatment before primary tank to remove grease:
Preaerate
• Waterborne diseases:
Typhoid, dysentery, cholera
• Oxygen depletion in water from waste caused by:
Bacteria
• Sludge wasting controls:
Aerator mixed liquor solids
• Safest sludge for soil conditioning:
Heat dried sludge
• Purpose of inlet baffle in settling tank:
Reduce velocity and disperse flow
• Purpose of forced draft ventilation in lift station:
Remove dangerous gases
• High-rate anaerobic digestion implies high:
Volumetric loading
• “Sour” digester conditions:
All of the above
• Volatile solids in sludge measure:
Food for bacteria
• White foam on aeration tank:
Underloaded organically
