关键词: 斜生栅藻, 固定化, 养殖废水, 氨氮, 生长速率, Scenedesmus obliquus, immobilization, aquaculture wastewater, ammonia nitrogen, grow

Abstract: Microalgae immobilization technology is a technology that immobilizes free microalgae cells on a carrier and changes it into a solid biocatalyst to be utilized. Immobilization can significantly improve the stability and longevity of algae cells, and is convenient for collection. At present, the "embedding method" in which microalgae cells are encapsulated in gel polymer by fixing method is often adopted due to its advantages of relatively simple operation, lower cost, less damage to cells, larger cell retention, etc. In order to explore the effect of immobilized microalgae on the removal of phosphate and ammonian from aquaculture wastewater, Scenedesmus obliquus was used as algae species, and sodium alginate embedding technology was used to carry out purification comparative tests of different algae embedding densities (S-1 group: 2.52×104cells/ml, S-50: group 1.26×106cells/ml and S-100 group: 2.52×106cells/ml), and the effects of embedding density on the growth of algae cells were also investigated. The results showed that the embedding density had a significant effect on the removal of phosphate and ammonian and the growth rate of algae cells (P<0.05). The higher the embedding density is, the better the removal effect of phosphate and ammonian is. The final removal rates of phosphate for S-1, S-50 and S-100 groups are 61.11%, 83.33% and 88.89%, respectively. And the final removal rates of ammonian are 39.95%, 50.00% and 57.53%, respectively. The main reason may be that the higher the concentration of algae cells is, the more effective algae cells participating in the reaction are and the higher the amount of nutrients absorbed is, so the efficiency of removing phosphate and ammonian per unit time is high. The growth rate K value of S-1, S-50 and S-100 groups of S. obliquus is S-1>S-50>S-100, i.e. the growth rate K value gradually decreases with the increase of embedding density of algae cells. This may be due to the fact that the larger the cell embedding density is, the greater the mass transfer resistance of CO2, O2 and nutrients is, and the lower the permeability of algae-spheres is. All these factors can cause subsequent algae cell proliferation to be affected.