This technology is employed in two main ways, ultraviolet absorption (UVA) and ultraviolet transmission (UVT). The UV254Sense can be used in either of these modes. UVA measures how much of the light is absorbed and is used for measuring the level of organics; it can also be used as a surrogate measurement for COD, TOC and DOC. Water treatment works, and sites using coagulation control commonly use this measurement. UVT measures how much light passes through the water and is used to determine the power required in UV-based disinfection processes.