Sequential use of Microalgae and Constructed Wetlands and its potential to remove organic load, toxicity and pharmaceuticals from urban wastewaters

Abstract

The present study aimed at to evaluate the performance of integrated system composed of microalgae (MA) and constructed wetlands (CW). The MA production tank was set up as a raceway type and microalgae of the genus Chlorella were inoculated, while the CW was set up inspired by the first stage of the French model and vegetated with the macrophytes Chrysopogon zizanioides, Typha domingensis and Dracaena trifaciata. The Hydraulic Retention Time in each unit was of 7 days, totaling 14 days of treatment. Promising results were obtained regarding the reductions of dissolved organic carbon (67.2%) and Total N (68.6%). The treatment was also able to fully remove the acute ecotoxicity against Dapnhia magna and the genotoxicity in the A. cepa test assay. Chromatographic analysis showed the presence of 9 pharmaceuticals in the raw wastewaters, whereas after the CW unit only residuals of dipyrone (1%) were still detected. Future recommendations include the investigation of the main removal mechanisms of the pharmaceuticals and improvements of the separation process of the MA.