there are lots of examples of ...
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
there are lots of examples of wastewater use from crops beginning thousands of years ago to recent uses of manure to lagooned wastewater, raw wastewater in Mexico , to highly processed water , e.g. in Monteray, California. Google them. There is a WHO Guideline for wastewater use in agriculture.