Safe Disinfection of Potable Water: Design of the North Stockton Pipeline Sodium Hypochlorite Facility
Format
SOECS Senior Project Demonstration
Faculty Mentor Name
Mary Kay Camarillo
Faculty Mentor Department
Civil Engineering
Additional Faculty Mentor Name
Luke Lee
Additional Faculty Mentor Department
Civil Engineering
Additional Faculty Mentor Name
Hector Estrada
Additional Faculty Mentor Department
Civil Engineering
Additional Mentors
Dr. Camilla Saviz / csaviz@pacific.edu / SOECS - Civil Engineering
Abstract/Artist Statement
Formation of disinfection by-products (DBPs) and trihalomethanes (THMs) in potable drinking water have become of increasing concern to the public in recent years. To mitigate this issue, the City of Stockton (City) converted their existing chlorine disinfection system to a safer method of disinfection, chloramination. Chloramination is the practice combining free chlorine with ammonia to form a weaker, but more stable disinfectant that does not interact with organic matter to form DBPs and THMs. However, events of DBP and THM formation have arisen because of the disinfection practices of Stockton East Water District (SEWD). SEWD currently disinfects their filtered effluent with 3 to 4 mg/L of chlorine gas, which is then conveyed through a 5-mile pipeline. During transportation of the disinfected water to the City’s customer connections, the high concentration of chlorine reacts with organic matter to form DBPs and carcinogenic THMs. The City has proposed to add sodium hypochlorite (hypochlorite) at the existing North Stockton Pipeline Ammonia Facility (NSPAF) site, located a few thousand feet upstream to the first customer connection. The North Stockton Hypochlorite Facility (NSPHF) was designed with two 7,000 gallons tanks to inject free chlorine concentrations ranging from 1.75 to 2.75 mg/L. The injected hypochlorite will be initially blended by two pumped-jet mixing nozzles to provide a mixing gradient of 800 to 1,000 s-1. Supplemental mixing will be provided downstream by one of three static mixers. A high-degree of blending must be achieved to ensure adequate blending across the pipeline cross-section before mixing with the injected aqueous ammonia to form mono-chloramines. The oral presentation on this design will cover the specifics of chloramination, the design of the NSPHF, and the impact of the facility’s operations on the City’s potable water supply.
Location
School of Engineering & Computer Science
Start Date
5-5-2018 3:30 PM
End Date
5-5-2018 4:30 PM
Safe Disinfection of Potable Water: Design of the North Stockton Pipeline Sodium Hypochlorite Facility
School of Engineering & Computer Science
Formation of disinfection by-products (DBPs) and trihalomethanes (THMs) in potable drinking water have become of increasing concern to the public in recent years. To mitigate this issue, the City of Stockton (City) converted their existing chlorine disinfection system to a safer method of disinfection, chloramination. Chloramination is the practice combining free chlorine with ammonia to form a weaker, but more stable disinfectant that does not interact with organic matter to form DBPs and THMs. However, events of DBP and THM formation have arisen because of the disinfection practices of Stockton East Water District (SEWD). SEWD currently disinfects their filtered effluent with 3 to 4 mg/L of chlorine gas, which is then conveyed through a 5-mile pipeline. During transportation of the disinfected water to the City’s customer connections, the high concentration of chlorine reacts with organic matter to form DBPs and carcinogenic THMs. The City has proposed to add sodium hypochlorite (hypochlorite) at the existing North Stockton Pipeline Ammonia Facility (NSPAF) site, located a few thousand feet upstream to the first customer connection. The North Stockton Hypochlorite Facility (NSPHF) was designed with two 7,000 gallons tanks to inject free chlorine concentrations ranging from 1.75 to 2.75 mg/L. The injected hypochlorite will be initially blended by two pumped-jet mixing nozzles to provide a mixing gradient of 800 to 1,000 s-1. Supplemental mixing will be provided downstream by one of three static mixers. A high-degree of blending must be achieved to ensure adequate blending across the pipeline cross-section before mixing with the injected aqueous ammonia to form mono-chloramines. The oral presentation on this design will cover the specifics of chloramination, the design of the NSPHF, and the impact of the facility’s operations on the City’s potable water supply.