Which calculation would you use if you want to determine how much chemical is needed for treatment based on mg/L dosage?

To determine how much chemical is needed for treatment based on a dosage expressed in mg/L, converting mg/L to lb/day is the correct approach. This calculation allows you to relate the concentration of the chemical (in mg/L) to the actual amount required for the flow of water being treated.

The conversion process typically involves knowing the flow rate of the treatment system in million gallons per day (MGD) or liters per day (LPD). By using the conversion factors between these units and the dosage in mg/L, you can accurately calculate the required amount in pounds per day. This ensures that the dosage is appropriate for the volume of water needing treatment, enabling the effective use of chemicals in the treatment process.

The other options focus on different aspects that, while potentially relevant in various contexts, do not directly answer the need for calculating the quantity of chemical based on a specified dosage. Converting gallons to liters pertains to unit conversion without addressing dosage. Calculating flow rate is crucial for understanding how much water is being treated but does not provide the necessary link to the chemical dosage needed. Measuring temperature is important for other chemical reactions or processes but is not directly related to calculating chemical dosage.