Rare earth clarifying agent and method for use in primary treatment of wastewater

A method for treating wastewater, including removing phosphorus while maintaining a ratio of C—P, comprising:

• dosing wastewater as part of a primary treatment or before the primary treatment with a clarifying agent of chloride salts of Ce and La having from 55.0-75.0% Ce and from 25.0-45.0% La and any balance being chloride salts of other rare earth elements, in an amount to provide a rare earth (RE):phosphorus (P) molar ratio of approximately 0.1:1 RE:P to approximately 0.8:1 RE:P and at a rare earth concentration of 0.01 to 0.5 mmol/L of wastewater,
• wherein the dosing provides a ratio of C to P ranging from 150 C:1 P to 25 C:1 P for dosed wastewater and wherein the dosing reduces one or more of orthophosphate (OP), total phosphorous (TP), total organic carbon (TOC), chemical oxygen demand (COD), and biochemical oxygen demand (BOD);
• and
• passing the dosed wastewater to a secondary treatment, wherein the ratio of C to P maintains microorganisms in the secondary treatment.