Answer: Biological Oxygen Demand.
- A Biological Oxygen Demand
- B Biochemical Oxygen Deficiency
- C Bacterial Oxygen Demand
- D Biological Oxidation Depth
Correct answer: A. Biological Oxygen Demand
Explanation: BOD stands for Biological Oxygen Demand - the amount of oxygen consumed by bacteria while decomposing organic matter in a water sample.
Sewage passes through physical removal (primary), then aerobic biological treatment where microbes form flocs that consume organic matter (secondary); the settled activated sludge is then digested anaerobically to produce biogas - a deliberate switch from aerobic to anaerobic conditions between stages.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers