Design-Build of Mercury Emissions Control Technology

Synagro operates the Woonsocket, Rhode Island Thermal Conversion Facility, which manages wastewater biosolids from Woonsocket and 50 area communities. The Woonsocket Facility processes both liquid and cake forms of biosolids via five dewatering centrifuges and a plant incinerator—a fluidized bed combustion process that handles up to 105 dry tons of biosolids per day. To improve the quality of emissions at the facility, Synagro reached out to Woodard & Curran to install mercury scrubber emission control technology through a design-build contract.

The $5.5 million project included the installation of a four-vessel fixed carbon bed mercury scrubber system to remove mercury from the flue gas path of the municipal sludge incinerator. The system consisted of constructing two structural steel platforms to accommodate the systems, new 42” stainless steel interconnecting ductwork, an automatic advancing fabric filter, induced draft booster fan, natural gas-fired heater, and all associated process controls. Our design-build team was responsible for overall project management, project controls, schedule, permits, engineering, equipment procurement, construction, commissioning, and emissions/performance testing.


The site posed several complications and real estate constraints, which ultimately required the relocation of existing equipment, roof demolition and renovation, as well as the construction of two 40 x 40-foot steel platforms for the new system at an elevation equal to the existing roof height. For example, a 250-ton crane was needed to relocate a 15,000-pound fiberglass vessel due to the reach and angle of the move.

Through diligent planning, careful attention to safety, and coordination with Synagro facility staff and numerous subcontractors, Woodard & Curran successfully completed the project on time and on budget with an accelerated schedule of 10 months from contract signing to operation.

Synagro Woonsocket LLC

Woonsocket, RI


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Woodard & Curran provides an integrated approach to design-build that results in informed, collaborative, and efficient project delivery.

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