Which pollutant is classified as conventional?

• A. Biochemical Oxygen Demand (BOD)
• B. Metals
• C. Ammonia
• D. Nitrogen

Answer: (A)

Conventional pollutants are the ones historically tracked because they reflect the basic oxygen demand and solid content affecting water quality. Biochemical Oxygen Demand (BOD) is a measure of the amount of biodegradable organic matter in water, and as these organics decompose, bacteria use up dissolved oxygen. High BOD means more oxygen is consumed downstream, which can harm aquatic life, so BOD is a classic conventional pollutant used in regulating wastewater.

The other options fit into different categories. Metals are considered toxic pollutants that require special toxic-pollutant regulation. Ammonia is a nitrogenous compound that’s treated as a nutrient and can be toxic at certain levels, rather than a conventional pollutant. Nitrogen, in general, is a nutrient pollutant managed separately from the conventional BOD/TSS set.