Here is the continuation of the multiple-choice questions asked in JKSSB Field assistant Question paper held on 21 May 2026 from question 43.
JKSSB Field Assistant Question Paper 2026 by Home Academy
43. Which of the following parameters measures both biodegradable and non-biodegradable organic matter in wastewater?
A) BOD
B) COD
C) Alkalinity
D) Total nitrogen
44. Coliform bacteria are used as indicator organisms because they:
A) Have very high treatment cost
B) Are present in human/animal faeces and are easy to detect
C) Are resistant to disinfectants
D) Indicate only physical pollution
45. The most common parameter used to assess the efficiency of a primary sedimentation tank is:
A) Removal of Suspended Solids (SS)
B) Reduction in COD
C) Reduction in BOD
D) Change in pH
46. For a given industrial wastewater sample, BOD is usually less than COD because:
A) COD measures only biodegradable organics
B) COD measures more organic compounds (including non-biodegradable) than BOD
C) BOD is determined at higher temperature
D) COD excludes toxic organics
47. The self-purification of a natural stream after discharge of sewage is retarded by:
A) Low dissolved oxygen and high organic load
B) High sunlight and temperature
C) Moderate temperature
D) High flow velocity
48. Which of the following is not a typical method of performance evaluation of a wastewater treatment plant?
A) Comparing design discharge with personal opinion
B) Checking percentage removal of BOD, COD, SS and nutrients
C) Monitoring effluent discharge against standards (e.g., CPCB)
D) Recording operating parameters (F/M ratio, SRT, DO, sludge volume index)
49. Which of the following is most closely related to the odour of sewage under anaerobic conditions?
A) Oxygen
B) Hydrogen sulfide (H_2S)
C) Carbon dioxide (CO_2)
D) Methane (CH_4)
50. The most widely used test for measuring dissolved oxygen consumed by microorganisms in 5 days at 20°C is:
A) COD test
B) \text{BOD}_5 test
C) TOD test
D) Residual chlorine test
51. Consider the following statements regarding physical characteristics of water and sewage:
I. Turbidity is a measure of light-scattering due to suspended solids.
II. Colour in water is mainly a biological characteristic related to algal blooms.
III. Temperature affects the solubility of gases and the rate of biochemical reactions.
Which of the statements given above is/are correct?
A) I only
B) I and III only
C) II and III only
D) I, II and III
52. Consider the following statements regarding chemical characteristics:
I. COD usually gives a higher value than BOD for the same wastewater sample.
II. High hardness in water is mainly due to dissolved \text{Ca}^{2+} and \text{Mg}^{2+} salts.
III. BOD is used to estimate the concentration of inorganic salts in water.
Which of the statements given above is/are correct?
A) I and II only
B) I and III only
C) II and III only
D) I, II and III
53. Consider the following statements regarding biological characteristics and performance evaluation:
I. Presence of coliforms in treated effluent indicates possible faecal contamination.
II. High Sludge Volume Index (SVI) indicates poor settling characteristics of secondary sludge.
III. Performance evaluation of a plant should be done only once, after construction.
Which of the statements given above is/are correct?
A) I and II only
B) I and III only
C) II and III only
D) I, II and III
54. Consider the following statements regarding self-purification and parameter interpretation:
I. Satisfying oxygen demand in a stream promotes self-purification.
II. High temperature always reduces the self-purification capacity of a stream.
III. Complete oxidation of organic matter by microorganisms produces CO_2, H_2O, and inorganic salts.
Which of the statements given above is/are correct?
A) I and II only
B) I and III only
C) II and III only
D) I, II and III
55. Match List-I (Parameter) with List-II (Type of Characteristic) and select the correct code:
List-I
i. Turbidity
ii. BOD
iii. Total coliforms
iv. COD
List-II
a. Total organic matter
b. Faecal contamination
c. Suspended solids
d. Biodegradable organics
Choose the correct match:
A) i-c, ii-d, iii-b, iv-a
B) i-d, ii-c, iii-b, iv-a
C) i-c, ii-a, iii-d, iv-b
D) i-b, ii-d, iii-c, iv-a
56. Match List-I (Performance Indicator) with List-II (Indication) and select the correct code:
List-I
i. BOD removal
ii. SS removal
iii. SVI
iv. F/M ratio
List-II
a. Settling properties
b. Organic-load efficiency
c. Solids-separation
d. Substrate/Biomass balance
Choose the correct match:
A) i-b, ii-c, iii-a, iv-d
B) i-c, ii-b, iii-d, iv-a
C) i-b, ii-a, iii-c, iv-d
D) i-d, ii-c, iii-b, iv-a
57. Match List-I (Test / Process) with List-II (Main outcome measured) and select the correct code:
List-I
i. \text{BOD}_5
ii. COD
iii. DO measurement
iv. SVI
List-II
a. Available Oxygen
b. Aerobic biodegradable load
c. Total COD
d. Settling ability
Choose the correct match:
A) i-b, ii-c, iii-a, iv-d
B) i-c, ii-b, iii-d, iv-a
C) i-b, ii-a, iii-c, iv-d
D) i-d, ii-c, iii-b, iv-a
58. Match List-I (Factor) with List-II (Effect on self-purification) and select the correct code:
List-I
i. High DO
ii. High organic load
iii. Sunlight
iv. Low temperature
List-II
a. Retards
b. Promotes
c. Enhances O_2 production
d. Slows reactions
Choose the correct match:
A) i-b, ii-a, iii-c, iv-d
B) i-a, ii-b, iii-d, iv-c
C) i-b, ii-d, iii-a, iv-c
D) i-c, ii-a, iii-b, iv-d
59. Arrange the following parameters in the order of increasing complexity (simplest first):
I. COD
II. Turbidity
III. BOD
IV. Total nitrogen and phosphorus
Choose the correct sequence:
A) II-I-III-IV
B) II-III-I-IV
C) I-II-III-IV
D) III-I-II-IV
60. Arrange the following steps in performance evaluation in logical order:
I. Compare effluent quality with standards
II. Collect and analyse samples
III. Calculate removal efficiencies (%)
IV. Identify operational issues
Choose the correct sequence:
A) II-III-I-IV
B) II-I-III-IV
C) III-II-IV-I
D) I-II-III-IV
61. Which of the following best defines Environmental Impact Assessment (EIA)?
A) A legal tax on polluting industries
B) A process of identifying, predicting, and evaluating environmental impacts of a proposed project and designing mitigation
C) Only a public-hearing mechanism for industrial projects
D) A method of financial auditing of environmental projects
62. An Environmental Impact Statement (EIS) is prepared:
A) Only after project completion
B) As a detailed written report summarizing the results of EIA, normally submitted with EIA notification
C) By the public, not by the consultant
D) Optionally, without any statutory backing
63. The Environment Management Plan (EMP) essentially:
A) Is only a financial plan for the project
B) Specifies mitigation, monitoring, and contingency measures to manage environmental impacts during construction and operation
C) Replaces the EIA process
D) Is prepared only for pollution control boards
Answer Key & Explanations (Q43 to Q63)
43. Which of the following parameters measures both biodegradable and non-biodegradable organic matter in wastewater?
- Correct Answer: B) COD
- Explanation: Chemical Oxygen Demand (COD) uses a strong chemical oxidizing agent (potassium dichromate) under acidic conditions to oxidize nearly all organic matter present in a water sample. This includes both complex compounds that microbes can easily eat (biodegradable) and tough synthetic structures that microbes cannot decompose (non-biodegradable).
- Why others are wrong: BOD explicitly measures only the organic fraction that can be broken down biologically by microorganisms.
44. Coliform bacteria are used as indicator organisms because they:
- Correct Answer: B) Are present in human/animal faeces and are easy to detect
- Explanation: Testing water directly for every single waterborne pathogen (like typhoid or cholera bacteria) is highly complex and dangerous. Instead, environmental engineers look for Coliforms (like E. coli). Since these bacteria reside in massive numbers within the intestinal tracts of warm-blooded animals, their presence in water serves as a reliable indicator of faecal contamination, and they are relatively simple and safe to culture in a laboratory.
45. The most common parameter used to assess the efficiency of a primary sedimentation tank is:
- Correct Answer: A) Removal of Suspended Solids (SS)
- Explanation: A primary sedimentation tank is a physical treatment unit designed to slow down wastewater flow so that heavy organic solids can settle to the bottom by gravity. Therefore, its performance is directly measured by how much Suspended Solids (SS) it successfully removes (typically around 50% to 70% efficiency).
- Why others are wrong: While settling solids removes some organic load (BOD/COD), that is a secondary effect. Major BOD and COD reductions happen downstream in secondary biological units.
46. For a given industrial wastewater sample, BOD is usually less than COD because:
- Correct Answer: B) COD measures more organic compounds (including non-biodegradable) than BOD
- Explanation: Since COD uses a harsh chemical process to break down almost everything (both biodegradable and non-biodegradable materials) while BOD only measures what living bacteria can digest over 5 days, the total oxygen required for chemical oxidation (COD) will always be greater than or equal to the biological oxygen requirement (BOD).
47. The self-purification of a natural stream after discharge of sewage is retarded by:
- Correct Answer: A) Low dissolved oxygen and high organic load
- Explanation: Self-purification relies heavily on aerobic microorganisms consuming organic waste and turning it into harmless byproducts. If a stream is overloaded with organic matter and lacks adequate Dissolved Oxygen (DO), anaerobic conditions take over. This drastically slows down (retards) the natural clean-up process and leads to foul smells and ecosystem collapse.
48. Which of the following is not a typical method of performance evaluation of a wastewater treatment plant?
- Correct Answer: A) Comparing design discharge with personal opinion
- Explanation: Performance evaluations must be entirely evidence-based, scientific, and quantitative. Relying on "personal opinion" to evaluate design discharge holds no standard engineering or regulatory value. Options B, C, and D list standard analytical protocols used globally to verify plant performance.
49. Which of the following is most closely related to the odour of sewage under anaerobic conditions?
- Correct Answer: B) Hydrogen sulfide (H_2S)
- Explanation: When dissolved oxygen is completely depleted in sewage, anaerobic bacteria break down sulfur compounds to get energy. This reduction process produces Hydrogen sulfide gas (H_2S), which is notoriously famous for its pungent, highly toxic, "rotten egg" smell.
50. The most widely used test for measuring dissolved oxygen consumed by microorganisms in 5 days at 20°C is:
- Correct Answer: B) \text{BOD}_5 test
- Explanation: The standard, globally accepted baseline parameter for measuring the biological strength of organic pollution is the 5-day Biochemical Oxygen Demand (\text{BOD}_5) test, incubated precisely at a standard environmental baseline temperature of 20°C.
51. Consider the following statements regarding physical characteristics of water and sewage:
- Correct Answer: B) I and III only
-
Explanation: * Statement I is correct: Turbidity is an optical property where suspended clay, silt, or organic particles scatter and absorb light passing through water.
- Statement II is incorrect: Colour itself is classified as a physical characteristic of water, not a biological one, even though biological events like algal blooms can alter it.
- Statement III is correct: Temperature has a massive physical and chemical impact; higher temperatures decrease the solubility of gases (like oxygen) but increase the speed of biochemical reaction rates.
52. Consider the following statements regarding chemical characteristics:
- Correct Answer: A) I and II only
-
Explanation: * Statement I is correct: As discussed in Q46, COD captures tough non-biodegradable organic matter that BOD misses, yielding a higher value for the same sample.
- Statement II is correct: Total hardness is chemically defined as the concentration of divalent metallic cations in water, predominantly Calcium (\text{Ca}^{2+}) and Magnesium (\text{Mg}^{2+}).
- Statement III is incorrect: BOD is exclusively used to measure organic pollution loading. It cannot detect or estimate stable, dissolved inorganic salts like sodium chloride or fluorides.
53. Consider the following statements regarding biological characteristics and performance evaluation:
- Correct Answer: A) I and II only
-
Explanation: * Statement I is correct: Finding coliforms in treated wastewater proves that pathogens from human or animal waste survived the treatment process, highlighting a breakdown in disinfection.
- Statement II is correct: Sludge Volume Index (SVI) measures how well activated sludge settles. A high SVI value means the sludge is light and fluffy (sludge bulking), indicating very poor settling characteristics.
- Statement III is incorrect: Performance evaluations must be conducted continuously or at regular operational intervals throughout a plant’s lifetime to track equipment wear, biological health, and regulatory compliance—not just once after construction.
54. Consider the following statements regarding self-purification and parameter interpretation:
- Correct Answer: B) I and III only
-
Explanation: * Statement I is correct: Meeting and satisfying the oxygen demand allows a stream to re-oxygenate and regain its healthy baseline state.
- Statement III is correct: When aerobic microbes completely oxidize organic waste, they convert it entirely into stable, oxidized end-products like carbon dioxide (CO_2), water (H_2O), and nitrates/phosphates (iningorganic salts).
- Statement II is incorrect: While high temperatures lower the maximum oxygen water can hold, they also speed up the biological activity of the bacteria cleaning the water. Therefore, high temperature doesn't always reduce self-purification capacity; it accelerates re-aeration rates up to a certain ecological threshold.
55. Match List-I (Parameter) with List-II (Type of Characteristic) and select the correct code:
- Correct Answer: A) i-c, ii-d, iii-b, iv-a
-
Explanation: * Turbidity is directly caused by suspended particulates blocking light \rightarrow Suspended solids (c).
- BOD represents the organic fraction that can be eaten by bacteria \rightarrow Biodegradable organics (d).
- Total coliforms signal potential pollution from fecal matter \rightarrow Faecal contamination (b).
- COD encompasses the entire oxidized organic footprint \rightarrow Total organic matter (a).
56. Match List-I (Performance Indicator) with List-II (Indication) and select the correct code:
- Correct Answer: A) i-b, ii-c, iii-a, iv-d
-
Explanation: * BOD removal measures the efficiency of eliminating dissolved organics \rightarrow Organic-load efficiency (b).
- SS removal tracks physical trapping units separating solids from water \rightarrow Solids-separation (c).
- SVI calculates the physical volume occupied by settled sludge \rightarrow Settling properties (a).
- F/M ratio balances incoming organic food (Food) against the active bacterial population (Microorganisms) \rightarrow Substrate/Biomass balance (d).
57. Match List-I (Test / Process) with List-II (Main outcome measured) and select the correct code:
- Correct Answer: A) i-b, ii-c, iii-a, iv-d
-
Explanation: This matches the essential purpose of each analytical test:
- \text{BOD}_5 measures the Aerobic biodegradable load (b).
- \text{COD} tracks the Total COD (c).
- \text{DO measurement} reads the Available Oxygen (a) currently in the water.
- \text{SVI} provides an index of the sludge's Settling ability (d).
58. Match List-I (Factor) with List-II (Effect on self-purification) and select the correct code:
- Correct Answer: A) i-b, ii-a, iii-c, iv-d
-
Explanation: * High DO fuels aerobic breakdown \rightarrow Promotes self-purification (b).
- High organic load exhausts oxygen supplies \rightarrow Retards clean-up (a).
- Sunlight triggers photosynthesis in aquatic plants \rightarrow Enhances O_2 production (c).
- Low temperature slows down bacterial metabolism \rightarrow Slows reactions (d).
59. Arrange the following parameters in the order of increasing complexity (simplest first):
- Correct Answer: A) II-I-III-IV
-
Explanation: * Turbidity (II) is the simplest and fastest to measure, requiring a simple optoelectronic meter slot.
- COD (I) requires chemical boiling but can be finished in about 2 to 3 hours.
- BOD (III) is more complex because it demands careful sample preparation, initial DO tracking, and a strict 5-day waiting period.
- Total nitrogen and phosphorus (IV) are the most complex, requiring advanced multi-step digestion processes, specialized reagents, and spectrophotometric instrumentation.
60. Arrange the following steps in performance evaluation in logical order:
- Correct Answer: A) II-III-I-IV
-
Explanation: The true scientific method for diagnosing a plant's performance follows this logical sequence:
- Go out into the field to Collect and analyse samples (II).
- Take that data and Calculate removal efficiencies (%) (III).
- Compare effluent quality with standards (I) to check for legal or regulatory violations.
- Use any gaps found to Identify operational issues (IV) and figure out what to fix inside the plant.
61. Which of the following best defines Environmental Impact Assessment (EIA)?
- Correct Answer: B) A process of identifying, predicting, and evaluating environmental impacts of a proposed project and designing mitigation
- Explanation: EIA is a formal management tool used to look ahead at the environmental consequences of a proposed development project before it is built. It maps out potential risks to air, water, and communities, and details mitigation steps to minimize those harms.
62. An Environmental Impact Statement (EIS) is prepared:
- Correct Answer: B) As a detailed written report summarizing the results of EIA, normally submitted with EIA notification
- Explanation: While EIA is the overarching structural process of study and analysis, the Environmental Impact Statement (EIS) is the actual, official document that compiles all those findings. It is submitted to regulatory bodies (like State or Central Environmental Authorities) to secure environmental clearance.
63. The Environment Management Plan (EMP) essentially:
- Correct Answer: B) Specifies mitigation, monitoring, and contingency measures to manage environmental impacts during construction and operation
- Explanation: The EMP is the actionable, practical playbook derived from an EIA. It outlines exactly who will execute, monitor, and enforce the promised mitigation measures, environmental safety protocols, and emergency responses throughout the project's construction and long-term daily operations.