Those #s are way too rosey!
Building it will be a 25 year education. 

The only way you get 40% more manure is if water or feed is wasted. The hog only puts out so much no matter what it eats.  

The application cost will be nearly the same as the manure value.

The other thing is if a field needs no P  but you put on 150# of p from manure . It really has no value to the farmer. 

Good luck gaining $8/ hd from a scale.