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Portland Water District Continues to Tackle PFAS Contamination in Biosolids; Advanced Study Makes Recommendations


Portland Water District (PWD) is finding innovative and cost-effective ways to meet the mounting challenges and limitations of biosolids management. Per State of Maine law, biosolids, the solids product of wastewater treatment, can no longer be applied to fields or composted as was the practice for many decades. It must be landfilled due to concerns over per- and polyfluoroalkyl substance (PFAS). This policy has created landfill capacity issues and challenges including finding bulky waste to mix with the biosolids to stabilize it for landfilling.

PWD recently adopted a Biosolids Master Plan (BMP), a technical study that detailed regional options for sustainable biosolids management. The plan recommended:

  • Engaging with regional partners to explore the idea of collaboratively implementing a single regional biosolids processing facility for multiple utilities in Maine.
  • Using solids processing technologies like anerobic digestion, drying, and thermal treatment to reduce the amount of biosolids that need to be disposed of.
  • And, upgrading existing dewatering and other solids handling processes at the PWD facilities.

“Left with dwindling and costly disposal options, PWD has taken proactive measures to address PFAS contamination and find solutions, which included commissioning a study to examine regional management options,” stated PWD’s Director of Wastewater Services Scott Firmin. “PWD is proactively engaged at the local, state, and national levels, exploring solutions to combat the widespread PFAS problem.”

PWD is anticipating that new processing steps will dramatically reduce the volume of solids to manage and generate renewable fuels which could reduce costs and greenhouse gas emissions. It will also reduce transportation and disposal costs.

One process being explored is primary sludge mesophilic anaerobic digestion (MAD). MAD could reduce the amounts of solids produced by 20-50%, and may generate other benefits valued at $1.2 million per year. In addition, there could be a significant environmental benefit. Of course, MAD has a significant capital cost which must be considered and evaluated.

“PWD is currently refining the recommendations, options, and possible funding sources. State and federal funding will be critical to advance a complete solution for Maine,” stated PWD General Manager Seth Garrison.

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