Study On The Cultivation And Air Flotation Of Energy Microalgae

With the development of global economy, the demand for energy is also increasing, in the future,fossil fuels will not be able to support the normal operation of society, so developing alternative sustainable production of fossil fuels become the dominant direction in the energy field.Microalgae draws the attention from all over the world, but high-cost and low-efficiency is the main obstacle of the development of microalgae biodiesel production,the microalgae harvest link is a key link and decides the cost of the whole process of microalgae biodiesel production which accounts for 20-30 percent of the total operating cost of harvesting. In this work,we select Chlorella and Porphyridium as the research objects, By single factor experiment and orthogonal experiments,the effects of nutrient element on the growth of microalgae cultivation and collectors on the recovery rate of microalgae flotation were examined.aimed at provide the basis data and information for the evaluation and high-efficiency of harvesting the microalgae,The main conclusions of this thesis are as follows:(1) Glucose,KNO3,KH2PO4 and MgSO4 were selected as nutrient element of Chlorella,Results showed that the biomass concentration and dry weight of Chlorella were the highest when the concentration of glucose,KNO3,KH2PO4 and MgSO4 were 20g/L、3.2g/L、0.08g/L and 0.08g/L7;NaHCO3 、KNO3 、 KH2PO4 were selected as nutrient element of Porphyridium,Results showed that the biomass concentration and dry weight of Porphyridium were the highest when the concentration of NaHCO3 、KNO3 、KH2PO4 were 3.2g/L,3.2g/L,0.1g/L;(2) Orthogonal experiments were employed to determine the optimum condition of microalgae cultivation,Results showed that dry weight of Chlorella could reach to 4.45g/L when glucose was 20g/L,C:N was 3:1,KH2PO4 was 0.05g/L,MgSO4 was 0.15g/L; dry weight of Porphyridium could reach to 3.72g/L when NaHCO3 was 3.2g/L,C:N was 4:1,KH2PO4 was 0.08g/L(3)To examine the effect of four collectors : C16 TAB, C14 TAB, Tea Saponin and Rhamnolipid on the surface hydrophobicity rate and recovery of microalgae by air flotation,the single factor experiment combined with air flotation were employed to determine theoptimum condition of recovery,Results showed that the collectors could change the surface hydrophobicity rate and improve the recovery rate obviously.C16 TAB was the best,the recovery rate of Chlorella could reach to 89.23% and Porphyridium could reach to 92.36%(4) Orthogonal experiments were employed to determine the optimum condition of microalgae harvesting,Results showed that the recovery rate of Chlorella could reach to94.29% when the dosage of C16 TAB was 80 ppm,pH was 9,airflow rate was160 L/h;the recovery rate of Porphyridium could reach to 96.31% when the dosage of C16 TAB was100ppm,pH was10,airflow rate was 160 L/h.