wastewater treatment by azolla filiculoides: a study on color, odor, cod, nitrate, and phosphate removal

The aquatic fern azolla, a small-leaf floating plant that lives in symbiosis with a nitrogen fixing cyanobacteria (anabaena), is an outstanding plant, thanks to its high biomass productivity along with its tremendous rate per unit area for nitrogen-fixation. the present study investigates the potential growth of azolla in secondary effluents for removal of cod, phosphorus, and nitrogen. results have shown that n and p removal at 100 ppm of each component in separate medium turned out to be 36% and 44%, respectively, whereas in case of a mixed solution of these two compounds, n and p removal declined to 33% and 40.5%, respectively. moreover, results have suggested that in the presence of phosphorus nitrogen absorption decreased. furthermore, azolla has revealed a high potential of cod removal by 98.8% in 28 days. finally, azolla may be one of the most promising agents to remove cod and treat nitrogen-free and phosphorus-rich wastewaters.