Peracetic Acid Disinfection for Industrial Wastewater Treatment – Washburn Tunnel Case Study

Washburn Tunnel, an industrial wastewater treatment facility in Texas, is required by permit to maintain an effluent concentration of Enterococci (Entero) less than 168 CFU/100 ml as a 30-day geometric mean, with a maximum daily concentration limit of 500 CFU/100 ml. However, the facility’s existing process configuration did not have the treatment capability to meet these limits. The Gulf Coast Authority (GCA) determined that an advanced disinfection technology would be required to consistently meet these permitted limits.GCA conducted an evaluation of available disinfection technologies that could potentially be implemented to achieve the permitted Entero limits. After an initial screening process followed by bench-scale, small-scale piloting and full-scale testing, peracetic acid (PAA) was identified as the most viable alternative to achieve the desired treatment goals. GCA ultimately elected to implement PAA as the new disinfection system.Final design of the new system consisted of a new contact tank as well as chemical storage and feed facilities. Limited facility space and constructability constraints required close coordination between the owner, engineer and contractor throughout the design process. Procurement documents were developed for an equipment lease and chemical purchase contract as part of the final design.GCA proceeded into construction using a construction-management-at-risk (CMAR) delivery method to reduce overall project schedule and obtain a guaranteed maximum price for construction. Upon completion of construction, six months of start-up testing was performed to confirm operation and optimize the dosing requirements.