NPTEL Wastewater Treatment and Recycling Week 9 Assignment Answers 2024
1. Which of the following contaminants require advanced treatment of wastewater for their intended removal:
a. Emerging contaminants
b. Heavy metals
c. Recalcitrant organic compounds
d. All of the above
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2. In wastewater, alum flocculation or lime-based precipitation may be used to remove:
a. Ammonia
b. Phosphorous
c. Refractory organics
d. Salinity
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3.
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4. The removal spectrum of an UF membrane is:
a. Better than MF and NF membranes, but less than RO membranes
b. Better than MF membranes, but less than NF and RO membranes
c. Better than NF membranes, but less than MF and RO membranes
d. Better than RO membranes, but less than MF and NF membranes
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5. The most commonly used adsorbent for the tertiary treatment of wastewater is:
a. Alum
b. Sand
c. Activated carbon
d. Natural clay minerals
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6. In ion-exchange systems operating down-flow in normal service run, upflow regeneration is preferred over down-flow, as:
a. Reverse-flow regeneration prevents ion-leakage in next cycle
b. Up-flow regeneration is less expensive
c. Up-flow regeneration requires much less time than downflow regeneration
d. All of the above
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7. Which of the following treatment processes is used for mineralization of organic compounds:
a. Adsorption and ion-exchange
b. Anammox process
c. Electrodialysis
d. Advanced oxidation processes
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8. Ultrafiltration is a:
a. Concentration driven diffusion
b. Temperature driven distillation
c. Pressure driven operation
d. Electric potential driven filtration
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9.
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10. Addition of ozone to treat wastewater, provides:
a. Denitrification and coagulation
b. Chlorination and electrodialysis
c. Co-precipitation of metal ions
d. Advanced oxidation and disinfection
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11. An adsorbent column containing 8 Kg of granular activated carbon (GAC) is being used to treat 12 kL of secondary treated wastewater in each cycle before being regenerated. The treatment is able to reduce polycyclic aromatic hydrocarbons (PAHs) levels from 40 mg/L to 6 mg/L. The concentration of PAH on GAC after end of cycle would be:
a. 34 mg / g GAC
b. 51 mg / g GAC
c. 175 mg /g GAC
d. 408 mg /g GAC
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12. A RO membrane for advanced treatment of wastewater is able to reduce TDS from 1600 mg/L (in RO feed) to 280 mg/L (in RO permeate). The unit is generating 45 % permeate and remaining 55 % is going to reject line. The TDS in RO reject would be:
a. 1320 mg/L
b. 1474 mg/L
c. 2680 mg/L
d. 4850 mg/L
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13. Additional dose of alkalinity needed for complete conversion of ammonia to nitrate, is (in mg/L
as calcium carbonate):
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14. Assuming density of oxygen as 1.91 kg/m3, the daily amount of oxygen required for complete
conversion of ammonia to nitrate, is (in m3/d):
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15. The daily amount of sludge produced is (in Kg/d):
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