Upgrading Biogas to RNG

What is AdvanSorb®-RNG?

Biogas, and even traditional natural gas, frequently has contaminants that need to be removed to purify it to its maximum energy and economic potential. ARI’s AdvanSorb®-RNG processing technologies make it possible to take in virtually any feed gas specification, virtually deliver any product gas specification efficiently, effectively, and economically.

  • ARI’s AdvanSorb®-RNG upgrading process consists of 2 distinct processes/systems.
  • ARI’s AdvanSorb®-RNG CO2+ process, removes pre-treatables (H2S, VOCs, Siloxanes), carbon dioxide and residual water
  • ARI’s AdvanSorb®-RNG NRU+ process, removes nitrogen and oxygen

Upgrading biogas to RNG requires the removal of a number of contaminants that are efficiently removed via two distinct PSA cycles/systems.  The first (CO2+) removes the contaminants that are heavier than methane.  The second (NRU+) removes the contaminants that are lighter than methane. These two systems can be purchased together or separately. However, efficiencies exist when used together.

*NRU = Nitrogen Rejection Unit

Using ARI’s AdvanSorb® processing technology for Renewable Natural Gas or Natural Gas purification means that your system is:

  • Robust: All contaminants can be removed to meet any gas specification
  • High Recovery: More of your finite resource can be monetized
  • Efficient: Relatively low operating cost means more profit and faster payback
  • Customizable: Utilize our modular design, or customize to meet your specific needs
Biogas Purification Process Diagram

Example case of LFG Composition

ConstituentTypical % In Feed To SystemTypical Pipeline Specification
Methane50.00%> 95.5%
Carbon Dioxide39.35%< 2%
Nitrogen8.00%< 4%
Oxygen1.50%< 0.2%
Water1.00%< 0.0147%
Hydrogen Sulfide0.0040%< 0.0004%
VOCs + Siloxanes0.1460%Varies
*Note that Digester Gas is Typically Predominantly Methane & Carbon Dioxide with less Nitrogen & Oxygen, and more Hydrogen Sulfide.

What ARI’s AdvanSorb®-RNG Process Removes Vs. Typical Technology Solution

Contaminant Typical Technology ARI AdvanSorb®--RNG Process 
VOCs + Siloxanes Pretreatment ARI AdvanSorb®-CO2+ System 
Hydrogen Sulfide Pretreatment ARI AdvanSorb®-CO2+ System 
Carbon DioxideCO2 Removal ARI AdvanSorb®-CO2+ System 
WaterCO2 RemovalARI AdvanSorb®-CO2+ System 
NitrogenNitrogen Removal ARI AdvanSorb®-NRU+ System 
OxygenVaries ARI AdvanSorb®-NRU+ System 

ARI AdvanSorb®-RNG 2-Stage Process Features, Benefits, & Capabilities

ARI’s AdvanSorb®-RNG 2-Stage process removes biogas pre-treatables (VOCs, siloxanes, H2S), CO2, residual water, nitrogen and oxygen over the course of two stages.   It utilizes Vacuum Pressure Swing Adsorption (VPSA) process technology developed and patented by ARI.  There are minimal technical limitations with inlet (e.g. gas compositions, flow rates, etc.) and product parameters.  Selecting ARI’s AdvanSorb®-RNG Two-Stage system provides you with a single-source gas upgrading technology provider who uses a common upgrading (VPSA) process of their own design and are committed to continuous improvement.

At the Landfill:

Can remove VOCs, siloxanes, hydrogen sulfide, water and carbon dioxide, nitrogen, and oxygen.

  • Allows for greater suction on the landfill, which means more methane, lower fugitive emissions, less odors, and vastly reduced well-tuning


Patented, reliable, and highly efficient multi-stage Vacuum Pressure Swing Adsorption (VPSA) process. Upgrades feed gas to RNG.

  • Removes contaminants to produce high-yield, high-purity, RNG
  • Moderate operating pressure means significant savings in CAPEX & OPEX compared to other technologies

Control system utilizes ARI’s proprietary adaptive control logic.

  • Compensates for fluctuations in feed flow, composition and ambient conditions, keeping product on-spec
  • Allows for data logging, trend analysis, and remote access to maintain peak performance
  • User-friendly training provided for operators & engineers


The ability to meet pipeline-grade natural gas, compressed natural gas (CNG), or liquid natural gas (LNG) specifications.

  • Flexible technology can be designed to best suit site infrastructure
  • AdvanSorb®-RNG 2-Stage process allows for 96.5%+ methane recovery and purity
  • ARI’s AdvanSorb®-RNG 2-Stage process can allow you to maximize system revenue, by optimizing product recovery and purity, while also keeping a low total cost of ownership.
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