Driving Sustainability: Reusing Microalgae Wastewater to Grow Pelargonium x hortorum

The scarcity of freshwater in many countries, the excessive production of wastewater, and the high demand for water for agriculture have been responsible for the implementation of wastewater for agricultural irrigation, thus achieving environmental benefits. The purpose of this research is to take advantage of wastewater generated in the production of microalgae and to analyze its impact on the growth and development of Pelargonium x hortorum, thus seeking to promote the reuse of resources and explore sustainable alternatives in agriculture. Two sources of wastewater were used for microalgae production (wastewater from the University of Almeria and slurry from a pig farm). The treatments used were: Control = (Tap water irrigation), Input-WW = (Irrigation with black water, inlet of the reactor) this wastewater was collected from Almeria University used at the beginning of microalgae production in the bioreactors, Outlet-WW = (Irrigation with black water, outlet of the reactor) - this is the wastewater collected after being treated with microalgae in the bioreactors, Input-WP = (Irrigation with slurry, inlet of the reactor) - this is the slurry that was used at the beginning of microalgae production in the bioreactors, Outlet-WP = (Irrigation with slurry, outlet of the reactor) are the purified slurry waters once they have been used for the production of microalgae in the bioreactors. The use of Outlet-WW has an adverse impact on plant diameter and number of flowers compared to the Control, which affected flower dry weight. The other biometric measurement parameters were not influenced. The WP wastewater showed elevated concentrations of nitrogen and potassium (N, K). On the other hand, the WW wastewater showed an elevated concentration of nitrogen, but also a high electrical conductivity (EC). This study concluded that the Outlet-WP treatment had no significant differences in dry weights compared to the Control treatment, but there was a significant reduction in the height and diameter of the plants as well as in the color of the leaves. This wastewater can be a source of nutrients for crop growth as well as a water source, but further research studies are necessary to determine the best way to apply it.