# [Week-3] NPTEL Wastewater Treatment And Recycling Assignment Answer 2023

NPTEL Wastewater Treatment And Recycling Assignment Answers 2023

## NPTEL Wastewater Treatment And Recycling Week 3 Assignment Answer 2023

1. Turbidity in water is usually measured based on:

a. Measuring rate constant of chemical reactions
b. Gravimetric measurements (by weighing)
c. Detecting scattering of light passed through water
d. Detecting potential for conducting electric current

`Answer:-For Answer Click Here`

2. Spectrophotometers are typically used to measure:

a. Redox potential
b. Colour
c. Conductivity and TDS
d. All of the above

`Answer:-For Answer Click Here`

3. At 20 °C temperature, and atmospheric pressure, the saturation dissolved oxygen level in water is approximately:

a. 9 mg/L
b. 2 mg/L
c. 0.5 mg/L
d. Zero

`Answer:-For Answer Click Here`

4. DO vary with water temperature and altitude, as:

a. Cold water holds more oxygen than warm water, and water at lower altitudes holds less oxygen than water at higher altitudes
b. Cold water holds less oxygen than warm water, and water at lower altitudes holds less oxygen than water at higher altitudes
c. Cold water holds more oxygen than warm water, and water at lower altitudes holds more oxygen than water at higher altitudes
d. Cold water holds less oxygen than warm water, and water at lower altitudes holds more oxygen than water at higher altitudes

`Answer:-For Answer Click Here`

5. The pH of a water sample was measured as 6.4 unit. The measured total alkalinity and measured total acidity of water would be:

a. Total Alkalinity = 0; Total Acidity = 0
b. Total Alkalinity = 0; Total Acidity > 0
c. Total Alkalinity > 0; Total Acidity = 0
d. Total Alkalinity > 0; Total Acidity > 0

`Answer:- For Answer Click Here`

6. Among the given options, the likeliest value of BOD of a wastewater sample, having 450 mg/L COD, is:

a. Zero
b. 270 mg/L
c. 450 mg/L
d. 700 mg/L

`Answer:-For Answer Click Here`

7. Match the type of effects of improper wastewater management with the related examples:

Class of pollutants in wastewater
(i) Organic pollutants
(ii)Emerging Contaminants
(iii) Nutrients
Examples
A. BOD and COD
B. Orthophosphate and nitrate
C. Antibiotics and pesticides

a. (i)-B. (ii)-A .(ini)-C
b. (i)-C. (ii)-A. (iii)-B
c. (i)-C. (ii)-B. (iii)-A
d. (i)-A. (ii)-C. (iii)-B

`Answer:-For Answer Click Here`

8. The BODs values of two wastewater samples A and B were measured as 80 mg/L and 210 mg L, respectively. This signifies that:

a. Sample A has lesser biodegradable organic matter load than Sample B.
b. Sample A has higher biodegradable organic matter load than Sample B.
c. Sample A has less quantity of biomass present than that in Sample B
d. Sample A has more quantity of biomass present than that in Sample B

`Answer:-For Answer Click Here`

9. Identify the correct statements regarding emerging contaminants, or contaminants of emerging concern: Statement

I: Emerging contaminants are generally bioaccumulative, but are non- persistent, and have very less toxicity. Statement
II: Emerging contaminants have become relatively easily identifiable with the new techniques for chemicals identification and separation.

a. Statement I is correct, while statement II is incorrect
b. Statement II is correct. while statement I is incorrect
c. Both, statements I and II are correct
d. Both, statements I and II are incorrect

`Answer:-For Answer Click Here`

10. A wastewater contains 180 mg L acetic acid (CH;COOH). The contribution of acetic acid to the theoretical COD of this wastewater is [Governing oxidation reaction: CH&COOH + 202 = 2H20 + 2C02]

a. 76 mg/L
b. 180 mg/L
c. 192 mg/L
d. 360 mg/L

`Answer:-For Answer Click Here`

11. 5 mL of a wastewater sample was diluted with aerated distilled water, made up to 300 mL in a BOD bottle. The initial DO was measured as 8.2 mg L, which dropped to 1.8 mg/L in 5 days’ time. BODs of the sample is:

a. 384 mg/L
b. 256 mg/L
c. 180 mg/L
d. 64 mg/L

`Answer:-For Answer Click Here`

12. In a MPN Test, 10 mL, 1 mL, and 0.1 mL of wastewater was inoculated in 5 replicates in nutrient broth, and resulted in 5, 2 and 0 positives tests, respectively, after 48 hrs of incubation. The MPN index / 100 mL of the wastewater would be (use the 5-replicates MPN table):

a. 20
b. 49
c. 70
d. 112

`Answer:-For Answer Click Here`

Question Statement (1315): A 100 mL wastewater sample was filtered using a GF/C filter paper of weight 1.750 g and the filtrate collected in a silica crucible of weight 24.802 g. Both, crucible and filter paper were dried for 24 hr in an oven at 104 °C. Post drying, the weight of the filter paper and crucible was measured as 1.924 g. and 24.928 g. respectively. Thereafter, both crucible and filter paper were placed in muffle furnace for 20 mins at 550 °C. Post ignition, the weight of the filter paper and crucible was measured as 1.842 g, and 24.866 g. respectively. Bases on the data, answer the followings:

13. The Total Suspended Solids (TSS) concentration in the wastewater is (in mg L)

`Answer:-For Answer Click Here`

14. The Volatile Suspended Solids (VSS) concentration in the wastewater is (in mg/L)

`Answer:- For Answer Click Here`

15. The Total Solids (TS) concentration in the wastewater is (in mg/L):

`Answer:- For Answer Click Here`

## NPTEL Wastewater Treatment And Recycling Week 2 Assignment Answer 2023

1. The quantity of municipal wastewater generated from a city depends on:

a. Population of the city
b. Water consumption pattern of the inhabitants
c. Both, population and water consumption pattern
d. Neither population nor the water consumption pattern

`Answer :- c`

2. Dry Weather Flow is:

a. The actual flow of sanitary sewage
b. The stormwater contribution to sewers in dry season
c. Combined stormwater flow plus sanitary sewage flow
d. Quantity of sanitary sewage flow subtracted from stormwater flow

`Answer :- a`

3. Identify the correct statements regarding design capacity of sewer systems:
Statement I:
Incorrect estimation of the quantity of sewage generated may lead to
inadequate or hydraulically inefficient sewer system design.
Statement II: Under-estimation of the design sewage flow will make the system uneconomical.

a. Statement I is correct, while statement II is incorrect
b. Statement II is correct, while statement I is incorrect
C. Both, statements I and II are correct
d. Both, statements I and II are incorrect

`Answer :- a`

4. Design period of various sewerage components are usually based on:

a. Availability of funds for design
b. Useful life of the specific components
c. The duration of the sewerage services required
d. Average life of the sewerage facility

`Answer :- b`

5. Which of these population forecasting method is likely to overestimate the forecasted population for a city of moderate size and age:

a. Arithmetic Increase Method
b. Incremental Increase Method
c. Geometric Increase Method
d. Logistic Growth Method

`Answer :- c`

6. Using Growth Composition Analysis Method (Demographic Method), population is estimated based on annual birth rate, death rate and migration rates. Which of these is relatively the most difficult to estimate:

a. Birth rate
b. Death rate
c. Migration rate
d. All of the above

`Answer :- c`

7. The peak factor is used to estimate peak for sewer designs. The correct relation between peak factor for sewage flow estimation with the increase in population, is:

a. Peak factors have large fluctuations for highly populated cities
b. Peak factor is independent of population increase
c. Peak factor typically increased with the increase in population.
d. Peak factor typically decreases with the increase in population.

`Answer :- d`

8. Population forecast in a logistic growth model is limited by the:

a. Availability of the master plan of the region
b. Exponential growth rate of the population
c. Migration rate of the population
d. Population carrying capacity of region

`Answer :- d`

9. As per CPHEEO Manual (20212), the conventional sewers shall be designed for a minimum sewage flow of:

a. 30 litres per capita per day
b. 55 litres per capita per day
c. 100 litres per capita per day
d. 250 litres per capita per day

`Answer :- c`

10. Which of the these may lead to additional inflow to sewer lines?

a. Water used from unaccounted private water supplies
b. Water used for gardening and horticulture
c. Water losses from water supply systems
d. All of the above

`Answer :- a`

Question Statement (11-13):
The population of a city was recorded as 2.5 lakhs, 3.2 lakhs, 4.1 lakhs, and 5.2 lakhs in
1991, 2001, 2011, and 2021, respectively. Based on the data, answer the following:

11. The forecasted population in 2041 using arithmetic increase method, would be (in Lakhs)

`Answer :-  6.6,7.4`

12. The forecasted population in 2041 using arithmetic increase method, would be (in Lakhs)

`Answer :- 8,9`

13. The forecasted population in 2041 using arithmetic increase method, would be (in Lakhs)

`Answer :- 7.2,8`

14. A city with 12 lakh populations receives 150 lped water supply. Assuming that 80% of the water used is received as municipal sewage, the maximum daily flow of sewage from the city, assuming a daily peak factor of 2, would be:

a. 360 MLD
b. 288 MID
c. 180 MLD
d. 72 MLD

`Answer :- b`

15. The average daily sewage flow from city is 16 MLD. Assuming daily and hourly peak factor as 2 and 1.5, respectively, the maximum (peak) hourly flow of the sewage would be:

a. 172 m°/h
b. 768 m3д
c. 1240 m’h
d. 2000 m3д

`Answer :- d`

## NPTEL Wastewater Treatment And Recycling Week 1 Assignment Answer 2023

1. Which of the following component of wastewater is often not considered as a resource?

a. Water
b. Nutrient
c. Organic matters
d. Pathogens

```Answer :- d. Pathogens

Pathogens are microorganisms, such as bacteria, viruses, and parasites, that can cause diseases. While other components of wastewater like water, nutrients, and organic matter can be treated and potentially reused or recycled, pathogens are typically not considered a resource due to their potential to pose health risks if not properly treated and removed from wastewater. The focus is on eliminating or reducing pathogens to prevent the spread of diseases rather than utilizing them as resources.```

2. Wastewater generated from laundry and showers are typically referred as:

a. Brown water
b. Greywater
c. Black water
d. Stormwater

```Answer :- b. Greywater

Wastewater generated from laundry and showers is typically referred to as greywater. Greywater is the relatively clean wastewater that comes from non-toilet fixtures, such as sinks, showers, bathtubs, and laundry machines. It contains fewer contaminants compared to "black water" (toilet wastewater), and it can be treated and reused for purposes like irrigation, flushing toilets, and other non-potable uses.```

3. Identify the correct statements regarding non-point sources of pollution:

Statement I: Non-point pollution sources are usually difficult to monitor and control
in comparison to point sources
Statement II: The individual as well as collective contributions of the non-point
sources are always small.

a. Statement I is correct. while statement Il is incorrect
b. Statement II is correct, while statement I is incorrect
c. Both, statements I and II are correct
d. Both, statements I and II are incorrect

`Answer :- a`

4. Sort the following in Point and Non-Point sources of pollution:

i. Industrial Effluent
ii. Urban runoff
iii. Discharge from sewage treatment plant
iv. Atmospheric deposition

a. Point Sources – i, iv; Non-Point Sources – ii, iii
b. Point Sources – i. iii: Non-Point Sources – ii. iv
c. Point Sources – ii. iii: Non-Point Sources – i. iv
d. Point Sources – ii, iv; Non-Point Sources – i. iii

`Answer :- b`

5. Adequate wastewater treatment may result in the recovery of:

a. Reclaimed water
b. Nitrogen and Phosphorous
c. Energy
d. All of the above

`Answer :- d`

6. Which of these is included in greywater:

a. Toilet flush
b. Urine
c. Kitchen drain
d. All of the above

`Answer :- c`

7. Identify the correct statements regarding contaminants and pollutants:

Statement I: A pollutant always has harmful effects on the surroundings while a contaminant may or may not have the same.
Statement II: A pollutant may be a component of the system while a contaminant is usually introduced from the outside.

a. Statement I is correct. while statement II is incorrect
b. Statement II is correct, while statement I is incorrect
c. Both, statements I and II are correct
d. Both, statements I and II are incorrect

`Answer :- c`

8. An example of the direct impact of inadequately managed wastewater on the ecosystem is

a. Eutrophication
b. Climate Change
c. Acid Rain
d. All of the above

`Answer :- a`

9. Which of this is not a technique for the wastewater treatment?

a. Septic Tank
b. Settling and filtration
c. Dilution with freshwater
d. Biological processing for organic contaminants breakdown

`Answer :- c`

10. Match the type of effects of improper wastewater management with the related examples:

a. (1)-B, (ii)-A (in1)-C
b. (i)-C. (ii)-A. (iii)-B
c. (i)-C. (ii)-B. (iii)-A
d. (i)-A. (ii)-C. (ini)-B

`Answer :- b`

11. Which of the following wastewater types are relatively easiest to treat for reuse applications?

a. Municipal sewage
b. Black water
c. Greywater
d. Industrial effluent

`Answer :- c`

12. Which of the following is more adequate as an example of wastewater reuse in environmental sector?

a. Discharge of treated sewage to agricultural fields
b. Discharge of untreated sewage to a river
c. Treated wastewater recycling for toilet flushing
d. Artificial groundwater recharge with treated sewage

`Answer :- d`

13. Typically, pollution load is considered highest in:

a. Municipal Wastewater
b. Industrial Wastewater
c. Agricultural Wastewater
d. Stormwater

`Answer :- b`

14. Which of the following is India’s central government programme does include wastewater or greywater management as one of their components?

a. Swachh Bharat Mission
b. National Mission for Clean Ganga
c. Jal Jeevan Mission
d. All of the above

`Answer :- d`

15. Identify the CORRECT statements regarding decentralized wastewater management:

a. Recycling of wastewater is comparatively easier
b. Disposal or treatment location may be far away from the origin point
c. Large wastewater treatment plant is needed
d. Long-distances transport of sewage is needed

`Answer :- a`