Reuse of wastewater from the production of microalgae and its effect on the growth of Pelargonium x hortorum

Different wastewaters have been used as microalgae culture media and in biomass production. A percentage of this medium must be replaced periodically. The use of treated wastewater for irrigation has economic and environmental benefits. The aim of this research is to reuse wastewater from microalgae production and evaluate the effects on the growth and development of Pelargonium x hortorum. The study evaluated three wastewater sources that come from three different culture mediums (purified water, water plus fertilizers, and water plus 10% pig slurry). The tested treatments were: Control- nutrient solution for Pelargonium, Inlet-PW-purified water, inlet of reactor, Inlet-FW-water + fertilizers, inlet of reactor, Inlet-10 MW- water with 10% pig slurry, inlet of reactor, Outlet-PW- purified water, outlet of reactor, Outlet-FW- water + fertilizers, outlet of reactor and Outlet-10 MW- water and 10% pig slurry, outlet of reactor. This study suggests that the Outlet-PW waste solution from microalgae production can be used as an alternative water resource for cultivating Pelargonium, since production was equal to that of the control. The use of Outlet-FW also produced results similar to the control, except that root dry weight decreased and shoots and leaf number increased. A negative effect on biomass dry weight using Outlet-10 MW wastewater was observed. Outlet-PW irrigation water showed high concentrations of N, Na and Cl. Outlet-FW presented high concentrations of N and Na. Outlet-10 MW irrigation water showed high concentrations of N, Cl, Na and K. The high concentrations of Cl and Na in these wastewaters limit their use for plants which are less tolerant to salinity.