QUESTION BANK
PHE
Assignment questions.
MODULE -4
1. Draw a flow diagram of a municipal sewage treatment plant including sludge
digestion.
Give the removal of important polluting parameters by each of the treatment units.
2. Discribe the importance of screens and types of screens in the sewage treatment
process.
3. Explain the functioning of screens and Grit chamber in the treatment of municipal
wastewater.
4.What are skimming tanks? Explain with a neat sketch.
5. Design a rectangular sedimentation tank for a population of 90,000
thousand, with an assured water supply of 140 lpcd, 80% of which reaches
the treatment plant. Assume
peak factor as 1.2, flow velocity = 0.3 m/min. Check for over flow rate.
6. Design a grit chamber for a town having a population of 1 lakh. Assume
suitable data necessary.
7. What is meant by activated sludge? Describe with neat sketches the
treatment of sewage by activated sludge process.
8. Describe in detail the working principle of primary Sedimentation tank.
MODULE -5
1. What are HRTF’s? Explain importance of recirculations and its effect on the
efficiency of HRTF’s.
2. Explain with a neat sketch, the working of trickling filter.
3. Describe with a neat sketch the principle, construction and working of a conventional
trickling filter and high rate trickling filter. Explain the importance of recirculation and
its effect on the efficiency of HRTF’s.
4. Design a high rate trickling filter for a sewage flow of 4.5 MLD, recirculation ratio
1.5, BOD of raw sewage 250 mg/l, BOD removed in PST = 30%, Final effluent BOD
desired 30 mg/l.
5. Discuss the stages of sludge digestion process, indicating the duration as well as end
products of each phase.
6. Design an oxidation pond for treating sewage from a hot climate for a colony of 5000
people, contributing sewage at the rate of 120 lpcd. The 5 day BOD of sewage is 300
mg/l.
S
1. Underline the need and importance of a planned public water supply
scheme in daily life.
2. Elucidate the permissible limits for the following parameters and
explain the environmental significance of each with respect to water demand: MPN, Nitrate, Iron and
Fluorides.
3. Explain the term “fluctuations in water demand” with a neat sketch.
4. The census data of a town is given. Forecast the population for the next three decades using the
following methods.
i) Geometrical increase method.
ii) Incremental increase method.
iii) Decreasing rate of growth method.
Year 1980 1990 2000 2010 2020
Population 81,420 1,25,000 1,70,000 2,20,000 2,30,000
5. Identify the factors that influence per capita demand.
6. The population of a city in three consecutive years i.e.2002, 2012 &
2022 is 80,000, 2, 50,000 and 4, 80,000 respectively. Determine
i) The saturation population.
ii) Equation of Logistic curve.
iii) The expected population in 2032.
7. Explain the different types of water demand.
8. Write the permissible limits for the following parameters in demand of water. State their effects if in
excess or deficient.
i) Turbidity.
ii) Hardness.
iii) pH.
iv) Chlorides.
9. In two periods each of 20 years, the population of a town has grown
from 30,000 to 1,70,000 and then to 3,00,000. Determine
i) The saturation population.
ii) Equation of Logistic curve.
The expected population after next 20 years.
