NJ S1 WASTEWATER EXAM QUESTIONS
AND ANSWERS. VERIFIED 2025/2026.
What is the main purpose of a trickling filter? - ANS To oxidize organic material
What is a typically acceptable D.O. in an aerobic digester? - ANS 0.5 to 1.5 mg/l
Which chemical is used to identify a chlorine leak? - ANS Ammonia
When using the proper chemical to identify a chlorine leak, what color will the cloud of smoke
be? - ANS White
Why is flooding of trickling filter media sometimes recommended? - ANS To control filter flies
What is a common method of determining the quantity of chlorine used each day? -
ANS Read the chlorine scale weight
What is the principle concept of the gravity belt thickener? - ANS Thickens through gravity
drainage
What is the percent BOD5 removal efficiency in this plant?
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Influent CBOD5 is 250 mg/l
Effluent CBOD5 is 3.5 mg/l - ANS 98.6%
In - out / in * 100
250 - 3. * 100 = 98.6
What is the RAS flow rate, in mgd, in this activated sludge process?
• Influent Flow is 575,000 gpd
• RAS rate is 55% of Q - ANS 0.316mgd
Q(mgd) * RAS% of Q
575,000gpd = .575 mgd
.575 * .55 = .316
TSS - ANS Total Suspended Solids
What is the percent TSS removal efficiency in this plant?
• Influent TSS is 200 mg/l
• Effluent TSS is 2.5 mg/l - ANS 98.8%
200 - 2.5 = 197.5/200 * 100 = 98.8
What piece of equipment is used in the volatile solids test? - ANS muffle furnace for burning,
desiccator for cooling and moisture control, and analytical balance for weighing.
What is the detention time in the aeration tank? (not including RAS flow)
• Influent Flow is 575,000 gpd
• Aeration Tank Dimensions are 100 ft. Long, 25 ft. Wide, and 14 ft. Deep - ANS 10.93hrs
Detention Time, hrs = V/Q
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
AND ANSWERS. VERIFIED 2025/2026.
What is the main purpose of a trickling filter? - ANS To oxidize organic material
What is a typically acceptable D.O. in an aerobic digester? - ANS 0.5 to 1.5 mg/l
Which chemical is used to identify a chlorine leak? - ANS Ammonia
When using the proper chemical to identify a chlorine leak, what color will the cloud of smoke
be? - ANS White
Why is flooding of trickling filter media sometimes recommended? - ANS To control filter flies
What is a common method of determining the quantity of chlorine used each day? -
ANS Read the chlorine scale weight
What is the principle concept of the gravity belt thickener? - ANS Thickens through gravity
drainage
What is the percent BOD5 removal efficiency in this plant?
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Influent CBOD5 is 250 mg/l
Effluent CBOD5 is 3.5 mg/l - ANS 98.6%
In - out / in * 100
250 - 3. * 100 = 98.6
What is the RAS flow rate, in mgd, in this activated sludge process?
• Influent Flow is 575,000 gpd
• RAS rate is 55% of Q - ANS 0.316mgd
Q(mgd) * RAS% of Q
575,000gpd = .575 mgd
.575 * .55 = .316
TSS - ANS Total Suspended Solids
What is the percent TSS removal efficiency in this plant?
• Influent TSS is 200 mg/l
• Effluent TSS is 2.5 mg/l - ANS 98.8%
200 - 2.5 = 197.5/200 * 100 = 98.8
What piece of equipment is used in the volatile solids test? - ANS muffle furnace for burning,
desiccator for cooling and moisture control, and analytical balance for weighing.
What is the detention time in the aeration tank? (not including RAS flow)
• Influent Flow is 575,000 gpd
• Aeration Tank Dimensions are 100 ft. Long, 25 ft. Wide, and 14 ft. Deep - ANS 10.93hrs
Detention Time, hrs = V/Q
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
