The high cost of harvesting microalgae is a major hurdle for the microalgae industry, and an efficient pre-concentration method is required. In this study, the effects of using different pH values (between pH 3 and 11) and calcium (Ca) concentrations (between 0 and 5 mM) on Chlorella vulgaris sedimentation were investigated by evaluating the spacio-temporal distributions of microalgae cells. Fast and efficient sedimentation occurred (within 10 min) at a high Ca concentration (5 mM) at pH 9 and 11.
View Article and Find Full Text PDFA novel coupling process using an aerobic bacterial reactor with nitrification and sulfur-oxidization functions followed by a microalgal reactor was proposed for simultaneous biogas desulfurization and anaerobic digestion effluent (ADE) treatment. ADE nitrified by bacteria has a potential to be directly used as a culture medium for microalgae because ammonium nitrogen, including inhibitory free ammonia (NH), has been converted to harmless NO . To demonstrate this hypothesis, Chlorella sorokiniana NIES-2173, which has ordinary NH tolerance; that is, 1.
View Article and Find Full Text PDFRemoval of dissolved oxygen from algal photobioreactors is essential for high productivity in mass cultivation. Gas-permeating photobioreactor that uses hydrophobic membranes to permeate dissolved oxygen (pervaporation) from its body itself is an energy-efficient option for oxygen removal. This study comparably evaluated the characteristics of various commercial membranes and determined the criteria for the selection of suitable ones for the gas-permeating photobioreactors.
View Article and Find Full Text PDFAmmonium removal by a coupling process of microalgae (Chlorella sorokiniana) with partial nitrifying granules was evaluated in batch reactors illuminated in a wide range of light intensities (0, 100, 450, and 1600 μmol photons m s). Ammonium oxidation performance for different light exposure time showed that the granules had a light stress tolerance at 1600 μmol photons m s for up to 12 h, but continuous illumination induced severe inhibition on nitrifying bacteria thereafter. Ammonium removal efficiencies at the end of tests were 66%, 62%, 5%, and -10% (due to ammonification) for 0, 100, 450, and 1600 μmol photons m s, respectively.
View Article and Find Full Text PDFSulfide inhibition to nitrifying bacteria has prevented the integration of digestate nitrification and biogas desulfurization to simplify anaerobic digestion systems. In this study, liquid digestate with NaHS solution was treated using nitrifying sludge in a sequential-batch reactor with a long fill period, with an ammonium loading rate of 293 mg-N L d and a stepwise increase in the sulfide loading rate from 0 to 32, 64, 128, and 256 mg-S L d. Batch bioassays and microbial community analysis were also conducted with reactor sludge under each sulfide loading rate to quantify the microbial acclimatization to sulfide.
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