Real world example-
A place we often stay is on my Dad's property in the desert. We poured a concrete pad and park the 5th wheel next to it. I buried a 50 gallon drum upright with the bottom cutout of it. I installed a PVC sewer hose connection in the top of the drum. We would park the 5th wheel at this spot during our many weekend stays. Plus we would bring the 5th wheel for one to two weeks long stays a couple of times during the year.
I would run the black tank sewer hose to the 50 gallon drum and dump the tank each time it was nearly full.
We used Thetfords chemical with the enzymes to digest waste in the tank each time.
After 10 years the lid on the drum was eaten through with rust. I looked inside and there was about 2 feetof toilet paper crumbs in the bottom. No signs of bodily waste. I would have thought it would have been full or nearly full of toilet paper and dried bodily waste.
It seems to me the enzymes worked.