| Discrete settling | (Environmental Engineering) Settling in which individual particles settle independently, neither agglomerating or interfering with the settling of the other particles present. This occurs in waters with a low concentration of particles. |
| Dissolved oxygen (DO) | (Environmental Engineering) The amount of molecular oxygen dissolved in water. |
| Dump | (Environmental Engineering) An illegal and uncontrolled area where wastes have been placed on or in the ground. See Landfill. |
| Effluent based standards | (Environmental Engineering) Standards which set concentration or mass per time limits on the effluent being discharged to a receiving water. |
| Facultative | (Environmental Engineering) A group of microorganisms which prefer or preferentially use molecular oxygen when available, but are capable of suing other pathways for energy and synthesis if molecular oxygen is not available. |
| Fluidization | (Environmental Engineering) The suspension of particles by sufficient upward velocity of the fluid. During fluidization the gravity force is overcome by a combination of buoyancy and fluid friction. |
| Gas stripping | (Environmental Engineering) Gas transfer of an undesirable gas from a water stream to the atmosphere. |
| Global warming | (Environmental Engineering) The long-term warming of the plant due to increases in greenhouse gases which trap reflected light preventing it from exiting to space. |
| Greenhouse gases | (Environmental Engineering) Gases which trap solar radiation. Of the solar energy entering the earth's atmosphere a portion is reflected back and a portion penetrates onto the earth's surface. The portion reflected back from the earth's surface is at a different wavelength that when it entered. Carbon dioxide and other gases, which pass solar radiation, absorb this reflected radiation, increasing the earth's temperature. This is much like a greenhouse, hence the name. |
| Groundwater | (Environmental Engineering) Water which is contained in geologic strata. Also properly written as two words, ground water. |