Determination of the nutritional values and some growth performance of cultured Azolla (Azolla filiculoides) using Beluga (Huso huso) farm wastewater

Phytoremediation is a sustainable and inexpensive technology and has become popular as an alternative solution to traditional wastewater treatment methods. The aim of this study was to use fish farm effluent as a culture medium for the Azolla and also to improve the effluent. For this purpose, the initial amount of 60 g of Azolla was dvided in two treatments with three replications, including Azolla in the wastewater of Beluga sturgeon farm (SW) and Azolla in the water of Anzali wetland (AL) which were grown in-vitro for 30 days. Sampling of water was performed to evaluate some water quality parameters at 10, 20 and 30 days. At the end of the experiment, the plant growth performance, fatty acid profile, and approximate composition were measured. The results showed that maximum amount of biomass (295.22 g) and plant width (9.64 mm) were observed in SW treatment (p <0.05). Also, the results of fatty acid composition showed that saturated fatty acids in SW treatment had a significant increase compared to AL treatment. However, unsaturated fatty acids in SW treatment showed a significant decrease compared to AL (p <0.05). In addition, a significant downward trend in the water quality parameters (phosphate, nitrate, and nitrite) was observed in SW treatment on day 30. The highest and lowest contents of fat and moisture were observed in SW treatment (p <0.05). Therefore, the production of Azolla in Beluga farm effluent can be an effective and cost-effective method due to the rapid growth rate, high ability to absorb the amount of phosphorus and nitrogen in water, as well high nutritional values (protein and lipid contents) and high diversity of fatty acids.