ARTICLE
Rural wastewater plant overcomes operational challenges of harsh winters
ClariPhos® enables Northern Ontario town to take control of TSS and phosphorus, while avoiding a costly, capital upgrade project
Many rural wastewater treatment plants in Ontario are exposed to harsh winter elements that can cause chemical feed lines to freeze, disrupt sludge settling, and impair biological treatment.
A small town of 1,200 people in Northeastern Ontario was no different. The town operates an extended aeration plant (3,274 m3/day rated flow) that occasionally experienced challenges in meeting its permit limits for total phosphorus (TP) and total suspended solids (TSS), 1 mg/L and 25 mg/L, respectively.
While coagulant addition was identified as a solution for improving TSS and TP treatment, the plant had not been designed and built with chemical storage, dosing, and freeze-protection systems. Ordinarily, this lack of infrastructure would be addressed with a costly capital project to purchase and install the required equipment. The remote town also faced accessibility and logistical challenges for receiving bulk deliveries of chemicals in the winter.
ClariPhos® Rare Earth Coagulant
After consulting with Bishop Water, the plant operators learned that ClariPhos® coagulant could be implemented more quickly and for far less capital cost than alternatives. The Bishop Water team sampled plant influent and conducted jar tests at its wet lab in Arnprior, Ontario to determine coagulant dosing and demonstrate performance. The Bishop Water team considered historic operations data such as influent flow rate, phosphorus loading, TSS, pH, and sludge production.
Unlike conventional aluminum- or iron-based coagulants, ClariPhos is made with the rare earth elements cerium and lanthanum. These elements form a strong, ionic bond with phosphorus, meaning far less coagulant is needed to achieve target phosphorus removal. ClariPhos also forms a denser, heavier precipitate which settles up to two times faster than conventional coagulants, enabling clarifiers to operate more efficiently and achieve higher quality effluent. Finally, Bishop Water manufactures ClariPhos in Canada to ensure a reliable, domestic supply and simplify procurement. .
In December 2025, a simple, coagulant system was installed in just a few hours by placing a tote of ClariPhos next to the clarifiers and plugging in a chemical feed pump to administer the product directly to the aeration basin. Shortly after, a portable enclosure was placed over the tote to protect it from snow. No storage tanks, buried chemical feed lines or heat tracing were needed.
ClariPhos was initially dosed at 20 mg/L to introduce the chemical and stabilize the process, gradually reducing the dosing to the recommended 10 mg/L.
Year-round Compliance
Within two weeks, total effluent phosphorus dropped from 0.7 mg/L to 0.2 mg/L and TSS dropped from 39 mg/L to 12 mg/L, well below the 1 mg/L and 25 mg/L permit limits. The clarifiers experienced a visible reduction in their sludge blankets and digested sludge solids increased by 1.2%. The plant achieved these results despite experiencing overnight lows of -36C and outdoor temperatures seldom topping 0⁰C during the period.
As the facility continues to optimize its chemical program, Bishop Water offers ongoing virtual support, reviewing plant data and suggesting operational enhancements.
