Pilot Testing Reveals Alternative Methods to Meet Wisconsin’s Low Level Phosphorus Limits

As part of ongoing efforts to develop a Study of Feasible Alternatives, the City of Fond du Lac, Wisconsin and the City of Waukesha, Wisconsin conducted four separate pilot studies to explore options for meeting upcoming ultra-low total phosphorus (TP) limits in the State of Wisconsin. The tests included multipoint chemical feed using ferric chloride, phosphorus removal using SorbX®-100, Blue Water Technologies BluePRO® filters, and Evoqua Water Technologies LLC’s CoMag® ballasted-flocculation system. The primary goal of the tests was to demonstrate the ability to consistently meet the potential TP discharge limit of 0.04 milligrams per liter (mg/L) for Fond du Lac and 0.075 mg/L for Waukesha. The pilot tests took place in 2013, 2014, and 2015.The multipoint chemical feed and SorbX®-100 pilot tests either did not meet the target or experienced reliability issues in meeting the target. The BluePRO® and CoMag® systems both reliably met the effluent target concentration.