While touring the brig aboard the U.S.S. Midway, I noticed a number of pipes running along the walls and ceiling. One was labeled Waste, another Soil, another Photo Lab.
Speaking with a docent later in the Engine room, he confirmed that the lines carried chemicals and other undesirable substances to holding tanks. The Soil stood for sewage, which would end up in Containment Holding Tanks (CHT), where it would be treated, before being dumped when the ship reached port. He said he served aboard the USS Peleliu, named for another WWII battle. For a time, he had overseen the CHT department.
He claimed that the CHTs were filled with worms, and as they filled with sewage, the worms went to town. As they fed on the waste matter, they grew in size and length. When the ship arrived in port and dumped the sewage that the worms had treated, the worms gradually shrank. If they didn't receive enough new sewage to feed on, the crew in charge of the CHTs had to give them some kind of nourishment to sustain them.
I asked the man what kind of worms they used in the CHTs, but he didn't know. Later, I searched out the matter online, but didn't find any references to the subject. My wife uses Earthworms in the compost bin to clean up some of the waste our household generates. It would be interesting to know what kind of worms they used aboard Naval vessels to clean up other types of waste.
Then again, another docent listened to our conversation, and twice he broke in with a smile to suggest that the next time we toured the Midway, we should wear tall boots. At the time, I wondered what he meant. But on reflection...