Development Of Photobioreactor With Semi-permeable Membrane And Feeding Device

Microalgae have high growth rate,high photosynthetic efficiency and high economicefficiency.However,the cultivation cost of microalgae is too high at present,which is the main factor restricting its industrial application.The semi-permeable membrane photobiorelector has the potential to solve the problem of high cultivation cost by in situ utilization of nutrients in surrounding water,but the nutrients in the water may not be sufficient enough to support efficient growth of microalgae.In order to solve this problem,we designed a semi-permeable membrane floating photobioreactor with a feeding device,which is expected to solve the problem of nutrient supply through slow release feeding.In a floating reactor with a semi-permeable membrane device,hydroxide ions can be released into the surrounding water through semi-permeable membrane,which may solve the problem of p H increasing problem when using bicarbonate as the carbon source.In this study,the formula of the membrane area in the semi-permeable membrane device and the feeding device design of the floating reactor were deduced theoretically.The relevant parameters were determined experimentally and the relevant formulas were deduced.The semi-permeable membrane device size,and finally according to the actual situation of the reactor and the device to determine the appropriate semi-permeable membrane area,and for difficult to meet the nutritional content,we select the appropriate feeding device size.After confirming the specific parameters and methods of the floating photobioreactor device,the microalgae culture experiment was verified.It was found that the p H of the experimental group with semi-permeable membrane was generally maintained in a relatively stable range,The p H of Spirulina were not more than 9.6,the final p H of Dunaliella salina was slightly higher than 10,and the p H of Chlorella seaweed was controlled at about 9.7,which proved the effect of the semipermeable membrane device on p H control and fed with the experimental group The concentration of nutrient is maintained at least on the half-saturation constant,indicating that the presence of the feed device can solve the problem of insufficient nutrients in the water.Based on the above advantages,the dry weight of the experimental group with the semipermeable membrane device and the feeding device was the highest in the three microalgae culture processes.Compared with the ordinary floating reactor,the highest yield of Spirulina increased in 10 days 23.8%,the highest yield of Dunaliellasalina was increased by 28.0% in 10 days,and the highest yield of Chlorellaincreased by173.3% in 7 days.In the process of microalgae culture,the ion concentration in the reactor has a certain relationship with the biomass.Compared with the actual experimental value,the total inorganic carbon and total nitrogen of Spirulina platensis and Chlorella vulgaris are predicted to have the maximum relative error were no more than 10%,validating the accuracy of the model between the biomass of the microalgae and the ion concentration in the reactor.In this study,a floating photobioreactor with a feeding device was successfully developed to solve the problem that mass transfer of some obligatory nutrients in the original system were too slow to support efficient growth of microalgae.Aslo,the hydroxide ions can be released through semipermeable membrane,and this can solve the problem of p H rise caused by consumption of bicarbonate.In this study,the basic model of nutrient mass transfer and microalgae growth was established,and the design principles and methods of the system were given,which laid the foundation for its future application.