That's going to depend on your type of aerator. Mechanical surface aerators have an efficiency of 3lb O2 / bHP-hr at standard conditions. So back of the hand would be about 1.8lb O2 / bHP-hr at process conditions (there's math behind this that is pretty simple, but I won't bore you with it.)

The oxygen demand for BOD treatment and stabilization (including endogenous respiration expected in lagoon systems since it's low F:M) is about 1.5lb O2 / lb BOD, excluding nitrification demand. So I'd expect about 0.8HP/lb BOD, which is about 1.3kW/kg. So somewhat close.

That is very much a rule of thumb and makes tons of assumptions. I can go over the math in more detail if you'd like.