It is now possible to transform wastewater into biofuel, with a positive energy balance, and to drive around 20 cars per hectare (for an annual distance of 18,000 km). Four times more than conventional biofuels, like sugar ethanol or palm diesel.
One of the challenges of R&D in the water sector is to make the best use of the waste produced in the different phases of the water cycle. With current technology, wastewater treatment involves a high expenditure of resources and, on the contrary, minimal reuse of the energy that these processes can provide.
One of the most ambitious lines of research is the use of wastewater as a raw material for obtaining biofuels. If possible, this would revolutionize the current paradigm of wastewater treatment: what until now had been viewed as an unwanted by-product would become a valuable resource.
All gas project.
The All-gas project demonstrates large-scale sustainable production of biofuels from low-cost microalgae crops using municipal wastewater. The entire process chain, from algae ponds to biomass separation, processing for the production and purification of downstream biofuels, as well as use in vehicles, takes place in a 4 hectares.
The specified algae yield of close to 100 t / ha / year is achieved by integrating and developing innovative systems to double the algae yield or reduce energy consumption with a new raceway design. If a net oil content of 20% could be extracted with compatible characteristics for conversion to FAME, enough biodiesel could be generated per year to circulate 20 cars per hectare of crop.
The residual algae are digested to produce biogas and CO2. The biogas is purified and compressed to be used as fuel for vehicles.
All gas pilot plant.
The industrial demonstration plant installed in Chiclana (Spain) includes:
- A cultivation area made up of 4 tracks with a surface area of 5,200 m2 each, and an average biomass production of 100 T / ha year.
- A separation and thickening system based on dissolved air flotation (3 units). At this point, the algal biomass is concentrated 100 times, consuming very little energy.
- A 2,750 m3 anaerobic biodigester in which more than 250 l of biogas can be produced per kg of volatile solid. About 40 cars can travel 18,000 km each with the biomethane resulting from the conversion of algal biomass.
- A plant for refining biogas into biomethane connected to a refueling station.
Project partners: Aqualia (Spain) as coordinator, BDI-Bio Energy International (Austria), Fraunhofer-UMSICHT (Germany), HyGear (Netherlands), University of Southampton (United Kingdom).
The project is co-financed by the European Commission.
More information: all-gas.eu