Portland Water District (PWD) is working on innovative and cost-effective alternatives in biosolid management.
According to State of Maine law, biosolids can no longer be applied to fields or composted as previously done. The biosolids must now be landfilled due to concerns over per- and polyfluoralkyl substances (PFAS).
This new policy has created landfill capacity issues and challenges, including things like finding bulky waste to mix with the biosolids to stabilize it for landfilling, according to a press release.
PWD has introduced and adopted a new Biosolids Master Plan (BMP). The BMP is a technical study that detailed regional options for sustainable biosolids management.
The plan recommended engaging with regional partners to explore the possibility of a single biosolids processing facility. The plan also recommended using solids processing technologies like anerobic digestion, drying and thermal treatment to reduce the amount of biosolids that need to be disposed. Finally, the plan recommended upgrading existing dewatering and other solids handling processes at the PWD facilities.
PWD anticipates that new processing steps will dramatically reduce the volumes of solids to manage. One process being explored is primary sludge mesophilic anaerobic difestion (MAD). MAD could reduce the amounts of solids produced by 20 to 50%, and may generate other benefits valued at $1.2 million per year, according to the press release. MAD has a significant capital cost, which must be considered and evaluated.
“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,” said PWD’s Director of Wastewater Services Scott Firmin in the press release.
“PWD is proactively engaged at the local, state, and national levels, exploring solutions to combat the widespread PFAS problem,” said Firmin.
