| Summary: | 碩士 === 大仁科技大學 === 環境管理研究所 === 101 === In this study, photobioreactor with 4 L of volume to cultivate Chlorella sp. was conducted for comparing the variations between algal surface and released organic matter while air gas flow rate and basic oxygen furnace slag were respectively changed. All experiments were controlled at light reaction of 12 hrs. with 1,700 lux. Also, the organic fluorescence of algae, expressed in excitation emission fluorescent matrix (EEFM), was obtained from the deduction of algal solution by the filtrate obtained from the 0.45 m membrane filtration of algal solution. Also, the surface charge and functional group were respectively measured by zeta meter and Fourier transform infrared spectroscopy (FTIR). As for the molecular weight of dissolved organic matter, it was measured by hybrid system of HPSEC (high performance size exclusion chromatography) plus DAD (diode array detector).
Biomass expresses by the absorbance value at 683 nm (OD 683) or dried biomass reveals that photobioreactor operated in high flow rate produced more increase of biomass than low flow rate. Algal growth was inhibited by addition of basic oxygen furnace slag as the air gas flow rate was constantly compared. However, high amount of basic oxygen furnace slag (BOFS) could promote more algal biomass than low amount of basic oxygen furnace slag. Without addition of basic oxygen furnace slag, the surface electricity of algae was ranged from -15 to -18 mV. Higher amount of BOFS could alter the algal electricity from negative to positive. It may be attributed from metal ions released from BOFS adsorbed on surface of algae. Chlorella sp. cultured at different air flow on the surface functional groups are hydroxyl, peptide bond, carboxylic acids and polysaccharides based, but the addition of BOFS reduces transmittances polysaccharide functional groups. Auto fluorescent intensity of Chlorella sp. with BOFS was higher than that without BOFS. Regarding to the organic fluorescent characteristic for Chlorella sp., two peaks location were appeared in EX 280/EM 330 nm (protein-like) and EX 440-480/ 680 nm (pigment). The more amounts of BOFS, the more decrease of fluorescence intensities in both peaks were found.
The released organic compounds from Chlorella sp. at different gas flow rates and BOFS, like protein (protein-like) and the like humus (huimc-like) components were measured from EEFM. Both fluorescent intensities decreased with the increasing air flow rate. The sutibale additiuon of BOFS could result in the increase of fluorescent intensities in both peaks than without BOFS. Regarding to molecular weight cut-off for released organic matter, its size was mainly located to 102-103 Da. After the addition of BOFS, the change of molecular weight was shifted from low fraction into high fraction, especially in longterm cultivation. For carbon fixation efficiency (CFE) , high air gas flow rate was less than low air gas flow rate. The addition of BOFS is not beneficial for the increase of CFE；however, CFE in higher amount of BOFS was larger that that in lower amount of BOFS.
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