UV Disinfection

Background

Wastewater treatment plants often employee ultraviolet (UV) disinfection as the last stage of treatment to meet strict bacterial limitations on plant discharges. A UV system’s reliability and efficiency is critical to mitigating the threat of permit violations and fines for the discharge of improperly disinfected wastewater effluent. During the UV disinfection process, treated wastewater is exposed to UV light, causing cellular damage to any microorganisms present. Therefore, these pathogens, such as viruses and bacteria, are incapable of reproduction or infection.

On open channel UV systems, either a controlling gate or weir structure regulate and maintain constant water levels over the UV lamps. For UV systems with horizontally-installed lamps, it is imperative to properly regulate wastewater levels to provide sufficient  UV exposure to contaminants. In addition, the UV system effluent gates serve as one of the last points of control before discharge.

Problem

Poorly-controlled actuators on this application leads to a variety of problems. If the gate cannot accurately control the water level over the UV lamps and gets too high, there may not be enough UV light to treat the additional water flowing through the channel. Consequently, this leads to potential discharge permit violations. Conversely, if the water level gets too low, the UV lamps can overheat, leading to maintenance issues. From a fail-safe perspective, if the UV system is compromised for any reason, and the effluent gate does not close, the plant can discharge non-permit water.

Solution

The reliability of REXA Linear and Rotary Actuators prevents downtime and maintenance costs on UV applications. More importantly, the superior control capabilities of REXA Linear and Rotary Actuators assures proper level control in plants’ UV channels. This allows them to meet disinfection standards for their effluent, reduce the threat of fines, and maximize UV bulb life. The easy addition of a fail-safe option to any REXA design gives the treatment plant peace of mind that a UV channel can be closed and isolated when an upset or emergency condition occurs. UV effluent control structures are tailor-made for the reliability, control, and fail-safe capabilities offered by REXA.

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