While greenhouses produce wastewater that may contain pollutants, microalgae-growing operations require a source of water – which is scarce in many regions. A new project aims to address both problems, by growing water-purifying algae in readily available greenhouse runoff.
Although greenhouses can recycle their own irrigation runoff, the water may contain nitrogen, phosphorous or other nutrients which were applied to the crops. If that water is reused while more such fertilizers are also applied, the accumulated nutrient load in the soil can become high enough to actually harm the plants.
Additionally, if the nutrient-rich runoff is instead passed directly into local waterways, toxic algae blooms may result.
That’s where the European REALM project comes in. Its name an acronym for “Reusing Effluents from Agriculture to unLock the potential of Microalgae,” the four-year initiative is focused on the building of inexpensive microalgae-growing ponds next to existing commercial greenhouses.
Irrigation runoff from the greenhouses will be channeled into the ponds, where the microalgae will consume the nutrients in the water. This will purify the water – so it can be safely reused for irrigation or released into the environment – while also providing food for the algae. Additionally, the setup will greatly reduce the amount of fresh, clean water needed to fill the growing ponds, leaving it available for municipal or agricultural use.
It is believed that once such systems are in place, they will decrease the nitrate content in greenhouse runoff to below the European Union limit, while also reducing the production costs of microalgae by 50 percent. Among other things, microalgae are currently used in animal feed, health supplements, cosmetics, biofuels and fertilizers.
The REALM project is funded by Horizon Europe, and its members include institutions or companies from Belgium, Finland, Germany, the Netherlands, Portugal, Spain and the UK.
Win-win REALM tech grows microalgae which purifies greenhouse runoff [New Atlas]