ICAR AICE-JRF/SRF (PhD): Dairy Chemistry, Dairy Microbiology, Dairy Technology, Dairy Engineering · 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 AICE-JRF/SRF spread across the units of Dairy Effluent Treatment & Environmental Management. Difficulty: 2 easy, 48 medium, 26 hard.
| BOD, COD, fats-oil-grease and nutrient measurement | 12 | |
| Anaerobic treatment and biogas | 11 | |
| Aerobic treatment: activated sludge and its variants | 10 | |
| Life-cycle assessment and carbon footprint of dairy products | 9 | |
| Nutrient removal and tertiary treatment | 8 | |
| Sources and characteristics of dairy effluent | 5 | |
| Sludge handling and disposal | 5 | |
| Preliminary and primary treatment: screening, equalisation, dissolved air flotation | 5 | |
| Water recovery from cow water and condensate | 4 | |
| Environmental management systems: ISO 14001 | 4 | |
| Discharge standards and permits | 3 |
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
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)
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
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
What dissolved oxygen is typically maintained in an aeration tank?
D. Near 2 mg/L
About 2 mg/L supports aerobic activity without wasting blower energy.
Further reading: Metcalf & Eddy, Wastewater Engineering
Why might trace elements be dosed into an anaerobic reactor treating dairy effluent?
C. Methanogens need nickel, cobalt and iron
Dairy effluents can be short of trace metals required by methanogenic enzymes.
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
In the Modified Ludzack–Ettinger process, where is the anoxic tank placed?
B. Before the aerobic tank
Nitrate-rich mixed liquor is recycled to an anoxic zone fed with raw effluent carbon.
Further reading: Metcalf & Eddy, Wastewater Engineering
In ISO 14001, what is an 'environmental aspect'?
B. An activity that interacts with the environment
Examples are effluent discharge, energy use and refrigerant leaks; impacts are the resulting changes.
Further reading: ISO 14001:2015
Ten here, 76 in the app. The Laisha app has every practice question we have written to ICAR AICE-JRF/SRF in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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