Pennsylvania WWTP chooses UV system for effective treatment
The Fredericksburg (Pa.) Sewer & Water Authority (FSWA) owns and operates two wastewater treatment plants, five wastewater pumping stations, three wells and three water storage facilities.
Proposed residential and business growth, as well as a mandate by the Pennsylvania Department of Environmental Protection (PADEP), required FSWA to provide a wastewater treatment plant for the South Fredericksburg area. The imposed mandate was due to soils in the area being unsuitable for on-lot septic systems. Many of the existing systems in the area were failing or had suspected failures that led to contamination of the wells used by many of the residents.
The original wastewater treatment plant utilized chlorine disinfection. Awareness of the environmental toll and long-term public health of chemical disinfection led the U.S. Environmental Protection Agency (EPA) to establish regulations to residual chlorine limits and disinfection byproducts (DBPs). When chlorine is added to wastewater, it can alter organic matter by forming DBPs. EPA believes there is sufficient association between DBPs and potential health hazards to warrant regulation.
FSWA constructed the Little Swatara Creek Wastewater Treatment Plant (WWTP) to accommodate serving the current population and proposed residential and business growth—there has been increasing demand due to the growing chicken processing industry in the area. The WWTP utilizes a sequencing batch reactor plant (SBR) for biological treatment and serves the residents and businesses of the village of Fredericksburg as well as the newly connected South Fredericksburg service area.
FSWA always looks for ways to reduce operating costs while maintaining or improving service to their customers. Steckbeck Eng. & Surveying Inc. was the consulting firm on the project. When selecting the technologies for the new plant, energy savings, low construction cost and reduced footprint while meeting permit limits were priorities. The WWTP was constructed using state-of-the-art controls and software for operations. To help achieve energy savings, LED lighting was installed throughout the plant. The result has proven to utilize the same amount of electricity as the old plant while treating more wastewater to a greater level on a daily basis.
Three ETS-UVTM SW systems were installed at the FSWA facility. Each ultraviolet (UV) chamber is designed for a peak flow of 0.65 million gal per day (mgd) to meet the permit coliform limit of 200 per 100 mL. Future expansion of the WWTP will treat average flow of 0.65 mgd and peak flow of 1.62 mgd, and will include construction of a third SBR basin and installation of a fourth UV unit.
Traditionally, wastewater UV systems were constructed as open-channel systems, utilizing racks of lamps immersed into a channel. These open gravity-flow channels suffer from many disadvantages—they provide poor hydraulic mixing, require very large footprints, are expensive to build, are difficult to maintain and are vulnerable to fluctuations in flow rate. Disinfection in a closed pipe ensures optimized hydraulics and prevents exposing the operator to wastewater and UV light.
UV disinfection eliminates the need to generate, handle, transport, or store toxic, hazardous or corrosive chemicals, and it requires less space than other methods. In addition, UV leaves no residuals that can be harmful to humans or aquatic life, and it is safer for plant operators.
ETS-UV disinfection systems are designed with sophisticated UV monitoring and controls to ensure consistent effective performance, as well as an automatic wiping system to keep quartz sleeves clean to prevent lamps from fouling.
Click here to learn more about the use of UV for wastewater treatment.