ICAR AIEEA-PG: Dairy Science (group 16) and Dairy Technology (group 17) · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersCharacterising and treating dairy wastewater, sludge and emissions, and measuring the environmental footprint of milk.
In the exams: ICAR AICE subject 34 Unit 4 (BOD and COD in dairy waste) and subject 35b Unit 1 (EMS); ICAR AIEEA-PG group 16 (disposal of dairy waste)
How our questions for ICAR AIEEA-PG spread across the units of Dairy Effluent Treatment & Environmental Management. Difficulty: 17 easy, 31 medium, 0 hard.
| BOD, COD, fats-oil-grease and nutrient measurement | 10 | |
| Aerobic treatment: activated sludge and its variants | 6 | |
| Anaerobic treatment and biogas | 6 | |
| Sources and characteristics of dairy effluent | 5 | |
| Life-cycle assessment and carbon footprint of dairy products | 5 | |
| Preliminary and primary treatment: screening, equalisation, dissolved air flotation | 4 | |
| Nutrient removal and tertiary treatment | 4 | |
| Water recovery from cow water and condensate | 3 | |
| Sludge handling and disposal | 2 | |
| Discharge standards and permits | 2 | |
| Environmental management systems: ISO 14001 | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A plant processing 500,000 L of milk a day loses 1% to drain. Taking milk BOD as 100,000 mg/L, what BOD load does this add?
D. 500 kg/day
5,000 L × 100 g/L = 500,000 g = 500 kg BOD/day.
Further reading: Tetra Pak, Dairy Processing Handbook
An effluent has a BOD of 1,800 mg/L and a COD of 3,000 mg/L. What is its BOD/COD ratio?
D. 0.60
1,800 ÷ 3,000 = 0.60, indicating a readily biodegradable effluent.
Further reading: APHA, Standard Methods for the Examination of Water and Wastewater
A reactor's influent COD is 4,000 mg/L and its effluent COD is 800 mg/L. What is the COD removal?
D. 80%
(4,000 − 800) ÷ 4,000 = 80%.
Further reading: Metcalf & Eddy, Wastewater Engineering
A process emits 10 kg of methane (GWP 27) and 1 kg of nitrous oxide (GWP 273). What is the total in CO₂e?
A. 543 kg
270 + 273 = 543 kg CO₂e.
Further reading: IDF carbon footprint standard for the dairy sector
Some warm-climate jurisdictions specify BOD over 3 days at 27 °C. Which BOD test is the usual international standard?
C. 5 days at 20 °C
BOD5 at 20 °C is the usual international test; BOD over 3 days at 27 °C is a warm-climate variant that gives similar values. Two hours at 150 °C describes the COD reflux, not BOD.
Further reading: Standard methods for the examination of water and wastewater (BOD)
Why is COD preferred to BOD for daily process control?
B. Results in hours
COD takes 2–3 hours, BOD days.
Further reading: APHA, Standard Methods for the Examination of Water and Wastewater
How are fats, oils and grease measured in effluent?
B. Solvent extraction and weighing
FOG is extracted from an acidified sample, the solvent evaporated and the residue weighed.
Further reading: APHA, Standard Methods for the Examination of Water and Wastewater
Why is dissolved air flotation favoured over primary settling for dairy effluent?
D. Fat floats, fine flocs settle poorly
Flotation exploits the low density of fat and fine protein flocs.
Further reading: Metcalf & Eddy, Wastewater Engineering
What does a high sludge volume index indicate?
C. Bulking
High SVI means sludge occupies a large volume per gram and settles poorly.
Further reading: Metcalf & Eddy, Wastewater Engineering
Under what conditions does denitrification occur?
A. Anoxic, with organic carbon
Without free oxygen, bacteria use nitrate as electron acceptor, releasing N₂.
Further reading: Metcalf & Eddy, Wastewater Engineering
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