| Term | Definition |
| methane | a gas (fuel!) which non-O2 Bacteria can make, in a sludge digester |
| fertiliser | useful mix of scum/sludge, that non-O2 Bacteria make in a sludge digester |
| trickling tank | where Aerobic Bacteria on carbon lumps will decompose sewage |
| activated sludger | where Aerobic Bacteria have O2 stirred in to decompose sewage |
| enzymes | non-living chemicals helping to break food into smaller lumps |
| chlorine | chemical added to kill any surviving Bad Bacteria in sewage |
| yeast | a fungus-type which makes ginger beer and bread |
| CO2 | a gas which is the "bubbles" in beer, and the "rise" in bread |
| O2 | that gas needed by the aerobic, "good" bacteria |
| antibiotics | chemicals usefully made by moulds, can help Doctors to kill bacteria |