The answer is true. It is because the activated sludge
process made use of the aeration in which air being mixed with a substance
together with a bacteria and protozoa that is in a biological floc that will
help treat the wastewater.
Here is what I found, its quite interesting, I hope it helps..
https://www.fbi.gov/services/laboratory/biometric-analysis/codis/codis-and-ndis-fact-sheet
