Confidential Client – Food Waste Anaerobic Digester On-Site Wastewater Treatment


The Montrose team was initially engaged as an Owner’s Representative to provide an independent assessment of ongoing design, engineering and construction progress at a confidential food waste digester and on-site wastewater treatment plant that was designed to take in approximately 100,000 tons of food waste per year and generate 3.2 megawatts of electricity. With respect to the wastewater generated at the plant, the on-site system is required to treat liquid digestate for the reduction of organics, nitrogen and phosphorus prior to discharge.

Following the delivery of the initial assessment to the project owner, Montrose was selected to take over the responsibilities and scope of work of the lead EPC firm. Taking into account the prior work that had been completed, Montrose was tasked with significantly redesigning portions of the facility, procuring new equipment, providing construction management services, and then starting up and operating the facility using an in-house operations and maintenance team.


Because the facility is located in a state with significant environmental restrictions, the system was designed with an on-site, comprehensive wastewater treatment system. At the time that the Montrose team was selected to take over the EPC scope of work, the wastewater plant had yet to be fully designed and key equipment had yet to be procured. In addition, due to state and city regulations, the facility was required to meet a stringent total nitrogen discharge limit on of 50 parts per million (PPM), with an indication that the limit could be lowered to 10 PPM in the future. This strict discharge limit posed a unique challenge to the Montrose team within the context of the application of this limit to a merchant food waste digester that would be accepting a wide range of food waste.


The Montrose team led the redesign of the wastewater system, the procurement of new equipment, the completion of construction, and the commissioning and startup of the facility. In order to meet the narrow discharge requirement, Membrane Bioreactor (MBR) technology was selected for deployment in conjunction with significant aeration basin and blower upgrades. (Other highlighted solutions implemented by the Montrose team encompassed the treatment of digested solids through to the recovery and drying of the resulting residuals in order to form a high-phosphorus soil amendment, as well as the recovery of ammonia as ammonium sulfate to be sold for fertilizer.)

Concurrent with the execution of the scope of work of the Engineering, Design and Construction Management team, the Montrose Operations and Maintenance team took over the operational portions of the facility and began to staff a dedicated, on-site O&M team for plant startup and long-term operations. With the completion of the redesign and upgrade work, the plant proceeded with start-up using a feedstock mix of source separated organics, fats, oils and greases (FOG), food processing and production waste, and fully-packaged, out-of-specification consumer goods. The plant is also staffed and operated, full-time, by the Montrose Operations and Maintenance team.

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