AlgaeBioGas: Algal wastewater treatment technologies and biomass production

AlgaeBioGas technology enables nutrient recycling from wastewater/biogas digestate, coupled with energy recovery and production of added value algal biomass.

Algal WWT technologies enable better reuse of nutrients, coupled with energy recovery and biomass production. Algal biomass is further used to make new products, depending on quality of WW used. The technology is most efficient in warmer climates.

Demonstration centre for algal treatment of biogas digestate was established in Zalog, Ljubljana, in scope of AlgaeBioGas project (Eco-Innovation). This is probably the biggest and oldest still working algal-biogas installation in EU. Demonstration centre was upgraded in 2017 to establish and develop algal-bacterial treatment process for treatment of salty waste water from food industry in scope of SaltGae project (H2020).

Demonstration centre is located next to 0.5MW biogas plant, providing heath and waste CO2 for algal ponds. Demo consists of two algal ponds: smaller (10m2) inoculation pond and bigger main pond (100m2), where process of algal-bacterial treatment of biogas digestate is taking place. Ponds are located inside the greenhouse, which enables adequate temperatures for algal growth in colder months. Ponds are equipped with mixing system, sensors for online measurements and process control, which enables remote control of the system through SCADA system.

Inflow of digestate addition to the ponds is controlled automatically, based on set values for several parameters. Algal biomass is harvested through sedimentation and DAF (diffused air flotation) process. Algal biomass produced has been tested for different applications such are production of biogas, bioplastics and biostimulans. The process is ongoing in scope of other EU projects (SaltGae, Water2REturn).

Algal-bacterial treatment technologies enable nutrient recycling from wastewater, energy saving in comparison with classical WWT and production of algal biomass with added value. Algal photosynthetic activity captures CO2 from fuel gases, while producing oxygen, which enables bacterial degradation of organic matter. Algae incorporate nutrients from WW (mainly nitrogen and phospohorus), resulting in algal biomass, which can be used as substrate for production of feed, fertilizers, biostimulants, bioplastics, biogas etc.


  • AlgEn, center za algne tehnologije, d. o. o.
  • Brnčičeva 29, SI-1231 Ljubljana
  • +386 (0)41 613 746

Project web page