27 Water & Wastewater Design questions from the Civil Design & Codes bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
B.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
C.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
D.Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
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2. Which term means: "CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water"?
Junior
A.Peak demand factors
B.Storm drain design
C.Per-capita water demand
D.Hazen-Williams formula
Answer + AI explanation with Pro
3. Which statement is correct?
Junior
A.Per-capita water demand — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
B.Per-capita water demand — fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
C.Per-capita water demand — rational method peak with runoff coefficient 0.9 for paved and 0.1 to 0.3 for lawns, using 2-year return period for residential and 5-year for commercial areas
D.Per-capita water demand — CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
Answer + AI explanation with Pro
4. What is Peak demand factors?
Junior
A.IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
B.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
C.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
D.Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
Answer + AI explanation with Pro
5. Which term means: "maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design"?
Junior
A.Activated sludge parameters
B.Peak demand factors
C.Storm drain design
D.Hazen-Williams formula
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.Peak demand factors — V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
B.Peak demand factors — maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
C.Peak demand factors — CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
D.Peak demand factors — aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
Answer + AI explanation with Pro
7. What is Hazen-Williams formula?
Junior
A.V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
B.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
C.conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge
D.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
Answer + AI explanation with Pro
8. Which term means: "V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE"?
Junior
A.Storm drain design
B.Hazen-Williams formula
C.Moving bed biofilm reactor
D.Sewer hydraulic design
Answer + AI explanation with Pro
9. Which statement is correct?
Junior
A.Hazen-Williams formula — IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
B.Hazen-Williams formula — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
C.Hazen-Williams formula — V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
D.Hazen-Williams formula — rational method peak with runoff coefficient 0.9 for paved and 0.1 to 0.3 for lawns, using 2-year return period for residential and 5-year for commercial areas
Answer + AI explanation with Pro
10. What is Sewer hydraulic design?
Mid
A.Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
B.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
C.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
D.V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
Answer + AI explanation with Pro
11. Which term means: "Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak"?
Mid
A.Peak demand factors
B.Sewer hydraulic design
C.Septic tank design
D.Sequencing batch reactor
Answer + AI explanation with Pro
12. Which statement is correct?
Mid
A.Sewer hydraulic design — fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
B.Sewer hydraulic design — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
C.Sewer hydraulic design — V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
D.Sewer hydraulic design — IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
Answer + AI explanation with Pro
13. What is Activated sludge parameters?
Mid
A.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
B.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
C.fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
D.conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge
Answer + AI explanation with Pro
14. Which term means: "conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge"?
Mid
A.Hazen-Williams formula
B.Sequencing batch reactor
C.Per-capita water demand
D.Activated sludge parameters
Answer + AI explanation with Pro
15. Which statement is correct?
Mid
A.Activated sludge parameters — conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge
B.Activated sludge parameters — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
C.Activated sludge parameters — fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
D.Activated sludge parameters — CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
Answer + AI explanation with Pro
16. What is Sequencing batch reactor?
Mid
A.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
B.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
C.fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
D.IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
Answer + AI explanation with Pro
17. Which term means: "fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs"?
Mid
A.Hazen-Williams formula
B.Activated sludge parameters
C.Sequencing batch reactor
D.Sewer hydraulic design
Answer + AI explanation with Pro
18. Which statement is correct?
Mid
A.Sequencing batch reactor — conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge
B.Sequencing batch reactor — fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
C.Sequencing batch reactor — maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
D.Sequencing batch reactor — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
Answer + AI explanation with Pro
19. What is Moving bed biofilm reactor?
Mid
A.CPHEEO recommends 135 lpcd for towns with piped sewerage, 150 for metropolitan cities and 70 where sewerage is absent, plus 15 percent unaccounted water
B.aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
C.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
D.IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
Answer + AI explanation with Pro
20. Which term means: "aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade"?
Mid
A.Peak demand factors
B.Sewer hydraulic design
C.Hazen-Williams formula
D.Moving bed biofilm reactor
Answer + AI explanation with Pro
21. Which statement is correct?
Mid
A.Moving bed biofilm reactor — IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
B.Moving bed biofilm reactor — conventional aeration at F/M 0.2 to 0.4, MLSS 1500 to 3000 mg/L, hydraulic retention 4 to 8 hours and sludge age 5 to 15 days with return sludge
C.Moving bed biofilm reactor — aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
D.Moving bed biofilm reactor — Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
Answer + AI explanation with Pro
22. What is Storm drain design?
Senior
A.rational method peak with runoff coefficient 0.9 for paved and 0.1 to 0.3 for lawns, using 2-year return period for residential and 5-year for commercial areas
B.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
C.fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
D.Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
Answer + AI explanation with Pro
23. Which term means: "rational method peak with runoff coefficient 0.9 for paved and 0.1 to 0.3 for lawns, using 2-year return period for residential and 5-year for commercial areas"?
Senior
A.Per-capita water demand
B.Hazen-Williams formula
C.Septic tank design
D.Storm drain design
Answer + AI explanation with Pro
24. Which statement is correct?
Senior
A.Storm drain design — rational method peak with runoff coefficient 0.9 for paved and 0.1 to 0.3 for lawns, using 2-year return period for residential and 5-year for commercial areas
B.Storm drain design — V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
C.Storm drain design — aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
D.Storm drain design — fill, react, settle, decant and idle phases run in one tank under timer control, removing the separate clarifier and suiting space-constrained STPs
Answer + AI explanation with Pro
25. What is Septic tank design?
Senior
A.maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
B.Manning n of 0.013 with self-cleansing velocity of 0.6 m/s at design flow and 3 m/s maximum, sewers up to 400 mm running half full at peak
C.IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
D.V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
Answer + AI explanation with Pro
26. Which term means: "IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench"?
Senior
A.Sequencing batch reactor
B.Activated sludge parameters
C.Peak demand factors
D.Septic tank design
Answer + AI explanation with Pro
27. Which statement is correct?
Senior
A.Septic tank design — IS 2470 sizes the tank for 24 hours detention plus sludge storage between desludging every 2 to 3 years, discharging to a soak pit or dispersion trench
B.Septic tank design — aeration tank with floating plastic carriers on which biofilm grows, giving compact treatment without sludge recirculation and easy capacity upgrade
C.Septic tank design — V = 0.849 C R^0.63 S^0.54 for pressure pipes, with C about 100 for old cast iron and 140 to 150 for new ductile iron and HDPE
D.Septic tank design — maximum daily demand is 1.8 times average and peak hourly is 1.5 times maximum daily, giving 2.7 times the average rate for distribution design
Answer + AI explanation with Pro
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