In population loading calculations, which components are included?

• A. BOD, COD, pH, Temperature
• B. BOD, TSS, Phosphorus, Influent
• C. BOD, TSS, Ammonia, DO
• D. BOD, TSS, Phosphorus, Flow

Answer: (B)

Population loading calculations estimate the daily mass of pollutants that a population contributes to the sewer system. The typical constituents tracked are BOD for biodegradable organics, TSS for suspended solids, and phosphorus as a nutrient. To turn those concentrations into a daily load, you need the influent stream data—the amount of wastewater entering the plant—so you can multiply concentration by flow to get mass per day. That’s why BOD, TSS, phosphorus, and the influent form the correct set.

Other options include parameters that aren’t pollutant loads (pH, temperature, DO) or substitute flow for the actual influent stream, which doesn’t capture the pollutant content by itself.