Trouble Shooting UV Systems: What To Do When The Lights Go Out?

Over the past ten years, ultraviolet (UV) technology has become a commonly applied method of disinfecting of wastewater effluent. UV disinfection involves passing wastewater effluent through a confined chamber with rows of underwater lamps emitting UV energy. Viruses and bacteria become inactivated upon exposure to dosages of UV energy, thereby disinfecting the wastewater.The UV system is defined by the physical (electrical and mechanical) requirements of the equipment. These requirements must be matched with the water quality of the wastewater plant to provide effective disinfection. For the purpose of trouble-shooting UV equipment, the UV system can be divided into three components: process, electrical, and mechanical. The process system deals with the quality of the water to be treated by the UV system and the disinfection goals that must to be attained. The electrical system consists of the lamps, wiring, and control system. Mechanical system includes the quartz sleeves, frames, cleaning mechanism, and reactor configuration.When the UV system functions as intended, it is easy for operations staff to maintain compliance with the treatment facilities NPDES permit requirements. Responses to the UV troubleshooting question in the 2001 Operations Challenge indicate that WWTP operators need additional information on troubleshooting UV systems. When UV systems fail to achieve the desired results, their electrical, mechanical, and process controls need to be examined to identify the cause of the failure and to take appropriate corrective actions.