Ultraviolet light is another disinfection method for destroying disease-causing organisms in wastewater effluent in onsite wastewater treatment systems. The UV light destroys the genetic material of microorganisms which prevents them from reproducing. Wastewater must pass through an advanced pretreatment component which is designed to remove most of the organic matter and suspended solids before it passes through the UV disinfection unit. Wastewater flows parallel to the UV light in a thin film to increase contact time. 
For the UV light to be effective, the UV radiation must come in direct contact with the microorganisms in the wastewater stream. Constituents allow a hiding place for the pathogenic organisms and shield them from the UV light. If the UV light does not come in direct contact with the constituents of concern, then it is useless. Turbidity, suspended solids, and flow rate of the wastewater must be kept at low levels to ensure proper treatment. Proper cleaning of the lamp sleeve and selecting the proper advanced pretreatment components will help ensure proper disinfection of wastewater.
Related Resources:
Operation and Maintenance Checklist: Disinfection Unit – UV Light
