From biogas to biomethane

Sludge is a by-product of the water treatment process. By digesting it, some of the organic matter in the sludge is converted into biogas. We use that biogas today mostly for the production of green electricity and green heat. But there's also a lot of residual heat, which we cannot always use optimally. If we valorize the gas component itself, no energy is lost. Out of 100% biogas, 60% can be converted into the valuable biomethane or green gas. Despite the phasing-out of gas from the energy mix, this green gas is far more valuable in the transition to a carbon-free future.

In 2021, Aquafin commissioned its first installation which converts biogas generated by sludge digestion into biomethane at our Antwerpen-Zuid WWTP. Following purification with activated carbon, the methane and CO2 components are seperated, leaving a green gas of the same quality as natural gas. On average, we inject 60 Nm³ of biomethane into the natural gas grid per hour on the site.

The project pays for itself through the sale of the gas molecule and green gas certificates. We use some of these to run our CNG company cars on bio-CNG.