By Hunter Stephens
Between 2018 and 2024, North Texas Municipal Water District (NTMWD) realized a 32 percent decrease in wastewater treatment chemical usage by installing equipment that automates dosing ferric sulfate, a chemical used to remove phosphorus during the treatment process.
Over the past five years NTMWD installed the equipment at five of its wastewater treatment plants (WWTP). The improvements underscore the Wastewater Division’s commitment to optimize chemical spending as part of its five-year plan.
NTMWD provides wastewater services for 23 communities and approximately 1.6 million residents in the North Texas area. Used water travels through 242 miles of wastewater pipelines to our WWTPs, where it goes through an extensive treatment process before it’s released as treated and clean water, also called effluent, into the waterways.
Phosphorus is a nutrient commonly found in lawn fertilizer. Because excess phosphorus in effluent can encourage algal growth in streams and lakes, removing it is part of the treatment process. Some of our WWTPs use special microbes that feed on phosphorus, but others employ a chemical process using ferric sulfate.
Ferric sulfate binds with phosphorus particles, making them heavier than water. The combined particles sink to the bottom of the treatment tank, joining the rest of the solid matter removed from the water during the treatment process.
Wilson Creek Regional WWTP was the first site to install advanced equipment, which provides real-time monitoring and adjustment of the phosphorus removal process for quick response to variable phosphorus levels in untreated wastewater. Previously, operators tested wastewater and manually adjusted ferric sulfate levels according to the results to ensure the effluent met regulations.
Automating the process led to more precise ferric sulfate dosing, quickly creating chemical cost savings. Following Wilson Creek, similar systems were installed at the Rowlett Creek, Stewart Creek, Muddy Creek and Panther Creek WWTP.
Using less ferric sulfate has benefits in addition to cost savings, including less maintenance of flow meters as well as ultraviolet light bulbs used to disinfect water, which extends the lifespan and effectiveness of these components.
Chemical costs have doubled since 2018 and this technology has minimized increases in our ferric chemical expenses while removing more phosphorus as our population increased. We remain committed to identifying cost-effective ways to reliably and efficiently operate the region’s facilities to treat wastewater for our communities and environment.