its industrial waste with ...

its industrial waste with high levels of heavy metals, phenols, ammonia and other chemicals, I suggest not to use them.  but if its farm waste or biological waste, it depends on the crop too.  in california, waste water from wineries can be used for irrigation at levels of below 250.  most i have seen are at bod below 80 and most are below 50.  and as for nitrogen, you have to do some pencil pushing but the limit is usually at 150 lbs an acre or 150 kgs there abouts per hectare per year.    the quality of nitrogen also is important.  because if its mostly ammonia, the crops die.  and if its mostly nitrates,  farmers tend to experience a lot of weeds.  so again, you have to do some pencil pushing and augment ammonia with nitrate heavy waste water and vice versa.   and please ignore the people who says not to use water with high levels of boron.  its actually good for  the crops.    its good to recycle as much as possible.