고농도 미세조류 배양을 위한 이산화탄소 고정화 및 평판형광생물반응기 배양제어시스템 개발

Abstract

In recent years, since use of indiscriminate fossil fuel has caused serious environmental pollution such as shortage of energy and global warming, new renewable energy should be requested immediately. New renewable energy using microalgae makes carbon dioxide reduce and biofuel production be possible. It makes all kinds of functional food as by-product. Microalgae are known to store large amount of lipid up to 50% of dry mass. Especially, production of biodiesel based on microalgae biomass is one of the cost-effective approaches, because microalgae can be cultivated with water and carbon dioxide. In this study, microalgae cultivation control system was developed to evaluate the amount and rate of carbon dioxide fixation. Chlorella sp. was selected because of containing the CGF. The proper setting of the photoperiod makes the growth of microalgae increase. Light transmission efficiency is very effective when applying to the flat panel photobioreactor. The light was illuminated to 24:0 by using light guide plate, and the efficiency was the best at 100μE/m^2/s. The cell growth was measured by indirect measuring method using a single substrate concentration OUR(Oxygen Uptake Rate). Dissolved oxygen and dissolved carbon dioxide were compared by dividing each exponential growth phase and lagicubation. Growth curve was approximated by Gompertz model, Logistic model, and baranyi model from microbial growth prediction model for the continuous culture. Baranyi model was suitable to predict the growth curve of Chlorella sp. because it has the highest R-squared. On-off control system was used to culture continuously chlorella sp. Process was contorlled by using real-time turbidity measurement by cell density. Since there are cell nonhomogeneously, fluctuation of measure signal is generated. Therefore, Signal was sampled by using box averaging. Error signals was removed to obtain the suitable transition of measured data using gradient vector. Sensor noise was reduced by using the Savitzky-Golay signal smoothing. Photosynthesis synthesized the cell components using carbon dioxide as a carbon source, and the fixation ratios of the rate of increase of the biomass and the carbon dioxide are proportional. The amount of carbon dioxide fixation from microalgae growth was obtained at a value of 3.569g·CO2/L by the dry weight in the batch culture. Carbon dioxide fixation rate was obtained by differentiating the amount of catbon dioxide to obtain a value of the 0.102g·CO2/L/day.