Municipal Wastewater Treatment is experiencing tremendous change with effluent discharge permits requiring higher levels of advanced treatment, including tertiary filtration. The Headworks BIO GSF, Gravity Sand Filter, is an upflow, continuous backwash, granular media filter that efficiently removes suspended and colloidal solids while providing a continuous supply of filtered water. The GSF is available in various circular and rectangular models for different flows and applications and is Title 22 Reuse Water certified.