What is the calculation for AOD?

What is the calculation for AOD?

• A. AOD=dose of ozone (mg/min)/flow (L/min)
• B. AOD=flow(dL)/dose(mg/min)
• C. AOD=dose(mg/min)*flow(L/min)
• D. AOD=dose(mg/min)/volume(L)

Answer: (A)

Understanding how to express ozone delivery as a concentration in water is what this tests. AOD represents the amount of ozone available per liter of water, so you want a mass per volume value. The ozone dose is given as mass per time (mg/min) and the flow is volume per time (L/min). Dividing the dose by the flow cancels the time units and leaves a concentration in mg/L. So the correct way to calculate AOD is to take the dose of ozone (mg/min) and divide by the flow (L/min), giving AOD in mg/L. If you multiply instead of divide, you’d end up with units like mg·L/min^2, which aren’t a per-liter concentration. If you invert, you’d get L/mg, which isn’t a concentration either. And using a different volume unit (like dL) would still not give the standard mg/L concentration, just a different but nonstandard unit. Example: with a dose of 60 mg/min and a flow of 6 L/min, AOD = 60 / 6 = 10 mg/L.

Understanding how to express ozone delivery as a concentration in water is what this tests. AOD represents the amount of ozone available per liter of water, so you want a mass per volume value. The ozone dose is given as mass per time (mg/min) and the flow is volume per time (L/min). Dividing the dose by the flow cancels the time units and leaves a concentration in mg/L. So the correct way to calculate AOD is to take the dose of ozone (mg/min) and divide by the flow (L/min), giving AOD in mg/L.

If you multiply instead of divide, you’d end up with units like mg·L/min^2, which aren’t a per-liter concentration. If you invert, you’d get L/mg, which isn’t a concentration either. And using a different volume unit (like dL) would still not give the standard mg/L concentration, just a different but nonstandard unit.

Example: with a dose of 60 mg/min and a flow of 6 L/min, AOD = 60 / 6 = 10 mg/L.