Is there any of the base/lye/KaOH/NaOH left in the methanol? If so, how is that dealt with in re-use. If not, is these some limit on the amount of times you can re-use the the methanol?

Doug

Excess methanol has to be removed from either the glycerol or (and) the biodiesel before it can be reused.

Recovery is achieved by distillation of the methanol from the glycerol/biodiesel.

Methanol that has been recovered via distillation no longer contains any catalyst, either NaOH or KOH.

The catalyst remains in the glycerol/biodiesel where it quickly forms soap as the methanol is removed.

There is no limit to the number of times you can reuse excess methanol after distillation. But, you will rarely recover enough methanol for a second batch of biodiesel. You will need to add additional methanol to your recovered methanol to have enough for your next batch. Assuming, of course, that both batches are the same size.