Digestate treatment and nutrient recovery at Biogas Plant Albertstroom
At the Albertstroom biogas plant in Grobbendonk, Trevi designed and implemented a comprehensive digestate treatment installation to enable nutrient recovery and ensure compliant wastewater discharge.
Challenge
The Albertstroom biogas installation in Grobbendonk processes 220,000 tonnes of organic waste annually and produces biogas, which is converted into electricity and heat via a combined heat and power unit (CHP). Part of the generated heat is used for electricity production through organic Rankine cycles, resulting in double green power generation. The remaining heat is used within the process itself or for wood drying. The organic waste is ultimately processed into compost and soil improver.
During the processing of organic waste, anaerobic sludge (digestate) is generated after the digestion step. This digestate requires further treatment.
Solution
The first step in the post-treatment process consists of separating the digestate into a liquid and a solid fraction (compost) using two decanter centrifuges.
The liquid fraction is subsequently treated in a biological wastewater treatment installation, where nitrification and denitrification remove nitrogen and organic carbon.
The produced biological sludge is concentrated through evaporation using mechanical vapour recompression (MVR). This process results in two streams:
- A concentrated nutrient stream, which is mixed with the solid fraction to recover nutrients
- A condensate stream
The condensate is largely reused on-site. The excess water is discharged into surface water after a stripping step.
Result
Trevi was responsible for the design and implementation of the installation, as well as for the start-up and further follow-up of the project.
The integrated treatment approach enables nutrient recovery, internal water reuse and compliant discharge, while supporting the circular operation of the biogas plant.
