So, just how "hazardous" can a tank full of poo be?

I worked in the environmental industry for 18 years and ran my own environmental consulting business for over 15 years. People will do all sorts of bizarre, dangerous and often times illegal things to dispose of hazardous waste. Maybe it wasn't just blackwater but some type of hazardous waste or maybe it was blackwater he knew to be possibly carrying some type of lethal biologics. It's too bad no one at least got his license number to pass on to the owner of the dump facility.