São Paulo, Brazil
CO₂, N₂ and O₂ Polishing of Landfill Biomethane
Project details
Technology: CO₂, N₂ & O₂ polishing PSA
Commissioned: 2020
Biogas Source: Landfill
Specifications
Capacity: 1,405 Nm³/h / 874 SCFM
Inlet Gas Composition: 93.6% CH₄, 2% CO₂,
3.6% N₂, 0.8% O₂, 100% RH
Design Specifications RNG / Biomethane: 96% CH₄, trace CO₂,
3.7% N₂, 0.3% O₂
At a landfill in São Paulo’s eastern zone, a single-valve IVYS Pressure Swing Adsorption (PSA) system further purifies gas from an existing water scrubber for initial CO2 removal, removing gas components to produce renewable natural gas (RNG) with 96% CH4 for pipeline injection or liquefaction.
The Challenge: Water-Wash Gas Just Short of Specification
The site had already upgraded its landfill gas using a water scrubber, bringing the methane (CH4) content to about 93.6%. However, this fell short of Brazil’s biomethane standard, ANP Resolution 685/2017, and the requirements for downstream liquefaction, which needs CO2 levels close to zero. The operator needed a polishing step that would:
- Remove the final 2% of CO2 to achieve trace levels without rebuilding the water-wash plant.
- Accommodate cold, wet-scrubbed feed.
- Maintain high recovery: any methane rejected by the polisher adds to the losses already incurred in the scrubber.
- Use local labor: the client would manage the civil works, piping, and installation, with IVYS providing supervision.
The Solution: A Compact Single-Valve PSA Polisher
IVYS (then known as Xebec Adsorption) supplied a skid-mounted fast-cycle rotary valve PSA polishing system that connects downstream of the water scrubber.
- Feed heating: An electric heater warms the scrubbed gas before it enters the beds.
- PSA: Adsorbent beds, switched by a single rotary valve, remove CO2 and some of the O2 and N2.
- Product: RNG exits through a product surge tank, which stabilizes pressure and flow.
GasGrid’s local team handled the civil works, buffer tanks, and interconnecting piping, while IVYS supervised adsorbent filling, commissioning, and the performance test.
In the client’s words
« We are happy to select the Xebec rotary valve PSA technology for this landfill application, and have already signed a Letter of Intent (LOI) to collaborate with Xebec on future projects. »
– Rodrigo Nogueira, Chief Technology Officer/Senior Project Manager, Gasgrid
Why It Matters for Landfill Operators – Closing the gap
Many landfill RNG plants using water scrubbers or membranes fall just short of grid or LNG specifications. This project shows how a small PSA polisher can close the gap.
- Bolt-on upgrade: adds to an existing water-wash plant rather than replacing it.
- Meets both market specs: trace CO2 meets pipeline requirements and supports liquefaction into bio-LNG.
- High recovery: 95% expected.
- Simple hardware: one rotary valve replaces the bank of switching valves used in a conventional PSA.
- Local installation: IVYS provided the core equipment and supervision, while the client’s crews handled the remaining construction.
