![A Settling Process Using Magnetite Ballast Helps A Massachusetts Plant Meet Strict Phosphorus Limits](https://cole-tpomag.imgix.net/https%3A%2F%2Fwww.tpomag.com%2Fuploads%2Fimages%2Fbillerica_4.jpg?crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=620&ixlib=php-1.1.0&q=75&w=1024&s=2343d45642c517547f0084c38ef60bc6)
From April through October (in-season), effluent from the Billerica (Mass.) Wastewater Treatment Plant averaged 0.80 mg/L total phosphorus. From November through March (off-season), it averaged 1.55 mg/L. In 2008, the U.S. EPA lowered the plant’s total phosphorus limit to 0.20...