Full Scale Webitat Installation in Woburn, MA – March 2023

In December of 2016 Entex’s Webitat submerged fixed film installation at the Superfund site at Woburn, MA started up. Eighteen Webitat units were installed, anchored on a specially built pier in this lagoon. The original objective was to remove ammonia from the system. While the treatment objectives were complex, involving a formula to include temperature and alkalinity, generally we needed to treat to below 1 mg/l of ammonia.

This followed an extensive full scale pilot demonstration starting in July 2012 which continued for over two years. The pilot study was challenging, involving floating four Webitat units in a baffled section of the lagoon, pumping influent into the baffled section and measuring the discharge. Among the challenges were the need to prevent leakage into the baffled section without disturbing the sludge layer, and the extremely low amount of phosphorus available to build cell mass. Another challenge was designing the Webitat units with a floor to ensure the units didn’t disturb the sludge layer and pull up contaminants. Toward the end of the demonstration project, a dye test was performed to measure the mixing capacity of the Webitat units, and a computer hydrodynamic simulation was designed to reflect the measured mixing efficiency.

Piloting Webitat Fixed Film Modules in Baffled section of lagoon – 2012 – 2014

We revisited this installation on a beautiful Boston spring day in March 2023 to check in on how the plant is operating. We met with Todd Majer of de Maximus, the company operating the Webitat system since the early days of piloting. The modules now are still floating like the pilot units; however, they are “docked” at two specially built piers. All required aeration is provided through the integral Webitat air scour system. Todd remarked that with these Webitat units, there just wasn’t much to do other than keep the blowers lubricated and oiled. He also noted that the discharge has consistently been below 1 mg/l of ammonia.

Close-Up View of Webitat Aeration – March 2023