For any drinking water utility using chloramine disinfection, nitrification is
a serious concern. The most important steps utilities can take to manage
nitrification are to thoroughly understand their systems’ chloramine
chemistry, establish an effective monitoring strategy, and deploy multiple
preventive strategies holistically throughout their distribution systems.
Managing residual disinfectant levels in a water distribution system can be a complex balancing act, involving frequent adjustments and boosting disinfectant to maintain residuals. With the addition of the Stage 2 Disinfection By-products rule, municipal operators in California struggled to control residual levels while avoiding unnecessary boosting.
A typically cold climate, the town of Atwater, Minnesota was no stranger to polar conditions. Formation of ice inside the city’s 100,000 gallon elevated tank frequently plugged the riser pipe, disabling flow and causing potential for serious damage to the steel tank. Anticipating a major storm, a PAX Mixer was installed to actively mix the water to prevent ice formation. During the record-breaking polar vortex storm, Atwater experienced more than a week of average temperatures below 0 degrees with extreme wind chill conditions, but after the addition of a PAX Mixer, ice formation was a problem of the past.
Anticipating implementation of the Stage 2 Disinfection By-products rule, operators in Rockville, MD evaluated a range of tools and technologies to manage the THMs in their drinking water system. Staff and engineers determined the combination of in-tank aeration and active tank mixing would reduce THM formation. Installation of a PAX Mixer and aeration system solved the water quality issues without decommissioning and rebuilding the tank.
Maintaining disinfectant residual levels in drinking water systems can be a challenge, even under normal conditions. Water must travel through several kilometres of pipes and is often stored in water tanks and basins before reaching customers. However, when the distance between the treatment plant and customer is extensive, maintaining adequate disinfectant levels becomes even harder.
Traditional improvement approaches of treatment plant upgrades or improvements to the primary water source have proven costly and time consuming. Many utilities have begun using technologies in the distribution itself to stabilize and improve water quality. The addition of powerful mixing systems and automated dosing has allowed operators to dial back the amount of total disinfectant required, improving the quality of the water without expensive treatment system upgrades.
As regulations tighten, utilities striving for optimum water quality are turning their attention to the distribution system. Within the system, even the highest quality water can deteriorate by stagnation and stratification. Despite today’s advanced treatment and disinfection technologies, water utilities are discovering the simple process of mixing is a cost-effective way to maintain the highest possible quality water in storage and throughout the distribution system.
In most northern climates, the winter cold brings with it the risk of ice formation inside water storage tanks, contributing to costly damage, corrosion and decreased water quality. PAX CEO Dr. Peter Fiske discusses options for ice prevention in this Q&A with WSO Magazine.
Rural water systems across the United States face a range of challenges in maintaining water quality in their distribution systems. Unlike large municipal systems, rural water systems often have a distribution network that is spread out over many miles. This can result in high water age and low disinfectant residual in parts of their system.
Pinellas County, Florida is typical of many major metropolitan water systems, with over 700,000 customers, 2,000 miles of piping and several large water storage facilities. Pinellas County Department of Environment and Infrastructure saw a decline in water usage over the past decade, which has increased water age and rates of nitrification in parts of their chloraminated system.