This case study will demonstrate how reverse osmosis (RO) was selected as an effective leachate treatment process for a private landfill, resulting in reduced trucking and increased acceptance of pretreated leachate by the county sewer department. The project background includes how changes in leachate volume and strength, and the original treatment system's inability to meet ammonia surcharge and discharge limits, necessitated significant upgrades. These challenges, coupled with increased reliance on offsite disposal, led to a comprehensive review and subsequent enhancement of the treatment system. Pilot testing of a full-scale reverse osmosis system (Rochem) was implemented in the third quarter of 2021 to evaluate technology performance including recovery rate and related data needed for full-scale design. Following the 3-month pilot test, RO was selected and the project moved into detailed design.

Early engagement with stakeholders included site planning, permitting, conceptual design, and integration with existing infrastructure. Close coordination with owner/operations staff, design partners, and regulators was a key to the project’s overall success and in meeting compliance deadlines during the detailed design and construction. The RO system was commissioned and started up within three months of construction completion in December 2023. It has been successful at maintaining compliance with sewer discharge requirements and exceeding the contractual recovery limit of 87.5%.

This session will include an overview of the RO technology used, a discussion of the operations at the plant, and a summary of quantitative treatment results. Attendees will learn how the implementation of RO technology allowed the landfill to increase discharge to the local sewer system. The site no longer hauls raw leachate offsite, with a much lower volume of residual requiring offsite treatment. Additionally, there have been no permit excursions, with the effluent quality much lower than permit requirements.