How to use "return on"

"Return on investment" is a noun phrase, and you will only confuse your readers if you try to use it as a verb. Return is of course also a verb, and one of its meanings is "To provide or bring back in exchange for effort or investment or as a result of ownership; to yield as a return. Freq. in to return a profit" (OED 16a: one citation is "1937 Life 26 July 85/2 (advt.) Big loads return the largest profit on drivers' wages"); you could make use of this to say, for example '...this could take years to return a reasonable income' if you do not wish to say 'this could take years to provide a return'.

But you seem to be asking specifically about the verb return on: there is no such thing. On is a preposition going with return; ;the mere fact that two words occur together in a piece of prose does not make them a recognized phrase, far less an idiom.

There are a number of grammatical errors in your sentence.

It is possible to use return, in this sense (and without the on) as a verb, but it wouldn't work very well here.

May I suggest that what you are saying is Most large schemes need substantial investment, and can take years to finish and deliver a return.

This is not to say that return on investment isn't a perfectly valid term. You could equally well say; Most large schemes cost a lot of money, and take years to finish and deliver a return on investment.