Landfill Leachate Treatment Plant Using Reverse Osmosis, New Hanover County in Wilmington, NC

SCS enabled the County to meet the new standards by successfully delivering the first RO-equipped leachate treatment plant in North Carolina.

New Hanover County has a 50,000 GPD treatment system for leachate generated at their 100-acre landfill. The treated effluent was discharged to a creek, but other discharge options included spray irrigation and wetlands disposal. The County needed to upgrade their treatment system to meet stricter regulatory standards for surface water discharges, particularly standards relating to metals (arsenic) and ammonia.

The County engaged SCS Engineers to design a 75,000 GPD plant that could consistently meet the discharge standards, even during cold weather. The project was fast-tracked to meet the regulatory deadline.


During the project term, SCS performed the following work to meet the County’s goals:

By conducting a leachate study SCS pinpointed characteristics that could affect the new treatment process. The study identified high ammonia concentrations (> 700 mg/l) that could inhibit the treatment process. The final design included a reverse osmosis (RO) filter membrane so the system would meet the regulatory standards for metals, and specifically arsenic.

SCS selected a new treatment process to meet client and regulatory requirements. The recommended process included a membrane bioreactor (MBR) with ultrafiltration (UF) followed by reverse osmosis (RO) membranes. The system included bioreactor tanks for the denitrification process.

SCS collaborated closely with Dynatech Systems to deliver the final process design and control.

We designed a 3,200-square foot control building and several pumping stations and force mains. Prepared a conceptual design and contacted process vendors for preliminary engineering and cost budgeting. Prepared the final construction plans and specifications, and provided construction phase services.

The NCDEQ’s sampling results released in 2019 show the landfill’s reverse osmosis (RO) system is effectively filtering out Per- and Polyfluorinated substances (PFAS) before discharging treated water into the Northeast Cape Fear River. The lab-certified results are available on the NCDEQ website.

Technical Expertise and Services Provided

  • Treat-Ability Study
  • Process Investigation
  • Site Engineering
  • Building Design
  • Processing Layout
  • Collaborate on Process Design
  • Geotechnical Investigation
  • Regulatory Approval
  • Construction Plans
  • Bidding Services
  • Construction Oversight