# NPTEL Wastewater Treatment And Recycling Week 3 Assignment Answer 2023

NPTEL Wastewater Treatment And Recycling Week 3 Assignment Answer 2023:- All the Answers provided below to help the students as a reference, You must submit your assignment at your own knowledge.

## 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

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2. Spectrophotometers are typically used to measure:

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Question Statement (13-15): 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)

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

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

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