A rendering of proposed Aries gasification plant in Sanford
Photo: Aries Clean Technology
By Lee Burnett
A Tennessee-based company is proposing to build a biosolids gasification plant in south Sanford to cook much of the region’s sewer sludge and convert it to biochar, a charcoal-like product useful to the concrete industry.
Construction of the plant by Aries Clean Technology would drastically reduce the volume of “forever chemicals” that have bedeviled the state since sludge-derived fertilizer was found to be contaminating farmland across the state in 2019. It would also expand the scope of the environmental debate over PFAS from groundwater contamination to air emissions. For Sanford, the plant represents an investment of at least $65 million and 30-plus full-time jobs, and hundreds of construction jobs.
The project has been in the works for more than a year and was first disclosed last week in a public notice in the Sanford Springvale News, indicating Aries intended to file an application with Maine’s Department of Environmental Protection for a permit through the solid waste management rules. The application and documentation were to be available for review at department offices and Sanford City Manager’s office. The notice said the plant would be built at Lot 4 on Cyro Road and would accept biosolids primarily from Maine, southern New Hampshire and eastern Massachusetts.
The plant would be larger than Aries’ first gasification plant in Linden, NJ, that a delegation from Sanford visited last year, according to Keith McBride, executive director of Sanford Regional Economic Growth Council. “That’s a very different facility; that was the prototype,” he said. The Sanford plant would be an improved version based on “the experience of learning best practices.”
McBride said the plant builds on Sanford’s clean energy sector, which includes 90 megawatts of installed solar capacity, second only to Farmington.
“Sanford has been working very hard to build a program for clean environmental technology,” he said. “We’re going even further now with this, addressing the biosolids problem.”
The Sanford Sewerage District is looking forward to having a more convenient, less expensive destination for its biosolids. “It would easily save us $100,000,” said Andre Brousseau, superintendent of the district. Sanford is one of the few districts that processes its biosolids into compost and trucks it to facilities in Quebec and Hartland. Shipping it to a gasification plant a few miles down the road would entail only dewatering it. A greater good is helping solve a statewide problem. “It could assist with the lack of landfill space,” he said. “This is a 90 percent reduction in volume.”
Aries declined to discuss the project, although the company sent a brochure about it. Mark Lyons, senior director of business development for Aries, said he would provide more information as a panelist on a Maine State Chamber of Commerce panel discussion on PFAS technologies and policies in Augusta on Jan. 22.
Also declining to discuss the project is the Conservation Law Foundation, which opposed a now-stalled Aries gasification plant in Taunton, MA. CLF issued a statement, making no mention of gasification. Instead, the environmental advocacy organization lauded the state for banning land application of biosolids and warned about the concentration of PFAS leaking from the Juniper Ridge Landfill north of Bangor, where much of the state’s sludge is landfilled and which is undergoing a contested expansion. CLF urged curbs on the production of PFAS, which is found in non-stick cookware, waterproof clothing, stain-resistant carpets and upholstery, fast-food packaging, cosmetics, firefighting foams, and cleaning supplies.
“The lack of great solutions for disposing of biosolids underscores the need for upstream solutions to PFAS. These are forever chemicals – so long as we allow their production, we’ll be stuck bearing the harms,” according to a statement from Nora Bosworth, CLF staff attorney.
Gasification is a multi-stage process, according to a company brochure. Wastewater solids are put through a dryer to evaporate most moisture, then cooked to produce biochar, which is sold to concrete companies, and syngas, which is used to power the plant. Thermal energy is also recovered from the syngas to dry incoming biosolids and generate electricity.
The most controversial aspect of gasification is the degree to which PFAS is destroyed in the process.
A chemical engineer hired by Aries said the chemicals are destroyed by high heat in three places: when the sludge is dried, when it is gasified at 1250 degrees and when syngas is processed through a thermal oxidizer at 1800 degrees, according to an April 2021 article in the Taunton Gazette. In the article, Dale Raczynski said a conservative estimate is that .01 percent of the PFAS in sludge would go out the smokestack and would be so diluted as to pose no environmental harm.
But opposition groups, which have stalled or defeated proposed Aries plants in Newark, NJ and Taunton, MA, have their own experts. (Aries also tried unsuccessfully to develop a plant in Kearny, adjacent to Newark). They say the degree of destruction may not be as high as advertised and would also be dependent on the plant always operating at peak efficiency. James Yeh, a biomaterials and engineering professor at Fisher College quoted by the paper, said the plant may have to burn natural gas to achieve the necessary temperatures. Experts also said the biochar would need to be tested to ensure that chemicals are well absorbed in it.
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