Comparison ability of algae and nanoparticles on nitrate and phosphate removal from aquaculture wastewater

Background: Aquaculture wastewater contains high levels of phosphate and nitrate. The reuse of this water requires standards beyond the secondary standards to eliminate more organic pollutants from aquaculture effluents. In this research, the removal of these pollutants from wastewater using Chlorella vulgaris and Fe3O4 nanoparticles in the reactor space was investigated. Methods: This study was conducted on fish farms effluent in the laboratory system. For this purpose, a 5-L semi-industrial reactor with a mixer blade, porous plate, and a compressor was designed. Chlorella vulgaris samples were collected from the natural environment and cultured in the laboratory environment. Also, Fe3O4 nanoparticles were prepared from Iranian Nano Pishgaman Company to make the desired solution. During the experiment (3 weeks), samples were taken weekly (in one phase) from the effluent. Dissolved oxygen (DO), pH, nitrate (NO3), and phosphate (PO4) factors from the influent and effluent of the farms were measured. The statistical data were analyzed using SPSS version 21 and Excel 2013. Results: The amounts of nitrate and phosphate were decreased by about 80.76 and 80.55% in the biological reactor, whereas these amounts were 70.52 and 70.48% in the nanoparticle reactor, respectively. Also, there were significant differences in the amounts of NO3 and PO4 between the control treatment and weekly treatment (P < 0.05). Conclusion: Based on the results, both reactors were able to reduce nitrate and phosphate from aquaculture wastewater, but the efficiency of the biological reactor was higher than that of the nanoparticle reactor.