[IzzieC (OP)]

Keith asks:

"Will mixing raw effluent with treated effluent cause pollution? Or will this be safe for the environment, for farm animals and to water veg for human consumption?"

What do you think?

[CliffordK]

That would be little different from dumping raw sewage into a river or stream.  And, downstream, it just gets polluted. 

Now, it may depend on the quantities.  I believe along the Colorado river, boaters are encouraged to pee in the river, but pack out solid waste.  And somewhere downstream that likely becomes drinking water.   

Plants, of course, use excrement as fertilizer.  But, other waste streams like petroleum oils or metals can contaminate sewage, and could potentially build up on soils.

The biggest issue with human sewage is the potential for fecal-oral disease propagation.  Many viruses are relatively short-lived in our environment, but bacteria and protozoa can be long-lived in the environment.  Food eaten raw like vegetables could get contact contamination, and potentially propagate the contamination.  Thus, illnesses such as Hemolytic E-Coli from salad bars, or potentially anything that someone handling the salad touched.

[Bored chemist]

Keith asks:

"Will mixing raw effluent with treated effluent cause pollution? Or will this be safe for the environment, for farm animals and to water veg for human consumption?"

What do you think?

I don't think it's possible to answer that question properly without someone clarifying it.