Publicly Owned Treatment Works-Wastewater Treatment Plants (POTW-WWTP)

Turn anaerobic digestion biogas into a cost effective, green vehicle fuel

When activated sludge from a POTW-WWTP is kept in an anaerobic environment, specialized bacteria develop that use the excess sludge as a source of organic matter for anaerobic digestion, a series of processes in which microorganisms break down biodegradable material in the absence of oxygen.

Anaerobic digestion is used all around the world to manage waste and/or to release energy and is rapidly growing as a source of renewable energy. The process produces a biogas, consisting of methane (CH4) and carbon dioxide (CO2), along with traces of ‘contaminant’ gases. This biogas can be used directly as cooking fuel, in combined heat and power gas engines, or upgraded to natural gas-quality biomethane. Now, POTW-WWTP operators can use the BioCNG™ system to convert this biogas into CNG fuel – at about half the price of gasoline or diesel!

Producing a fuel from POTW-WWTP biogas to meet engine specifications

To make a fuel that will meet current CNG engine specifications, the BioCNG system includes equipment that cleans and conditions the LFG.

Treatment systems remove H2S, volatile organic compounds (VOCs), siloxane and CO2. After cleaning, filters remove particulates, and chillers and desiccants remove moisture. After conditioning, the fuel is routed to a CNG fueling station where it is further dried and compressed for use in CNG vehicles. Waste gas and condensate returns to the facility’s existing environmental management systems. For more information on how the system works, [Link to video?]

The BioCNG system is fully automated, and designed to allow the conditioned biogas to be used directly as vehicle fuel or mixed with natural gas to produce a CNG/BioCNG blend. This mixing of fuels is similar to vehicle fuels containing blends of biodiesel or ethanol.