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Dewatering of Scenedesmus Obliquus Cultivation Substrate with Microfiltration: Potential and Challenges

Marco Malaguti,Lorenzo Craveri,Francesco Ricceri,Vincenzo Riggio,Mariachiara Zanetti,Alberto Tiraferri,

《工程（英文）》 doi: 10.1016/j.eng.2023.07.010

摘要： In the microalgae harvesting process, which includes a step for dewatering the algal suspension, directly reusing extracted water in situ would decrease the freshwater footprint of cultivation systems. Among various algae harvesting techniques, membrane-based filtration has shown numerous advantages. This study evaluated the reuse of permeate streams derived from Scenedesmus obliquus (S. obliquus) biomass filtration under bench-scale and pilot-scale conditions. In particular, this study identified a series of challenges and mechanisms that influence the water reuse potential and the robustness of the membrane harvesting system. In a preliminary phase of this investigation, the health status of the initial biomass was found to have important implications for the harvesting performance and quality of the permeate stream to be reused; healthy biomass ensured better dewatering performance (i.e., higher water fluxes) and higher quality of the permeate water streams. A series of bench-scale filtration experiments with different combinations of cross-flow velocity and pressure values were performed to identify the operative conditions that would minimize energy requirements while maximizing water productivity. The optimal conditions, 2.2 m·s⁻¹ and 1.4 bar (1 bar = 10⁵ Pa), respectively, were then applied to drive pilot-scale microfiltration tests to reuse the collected permeate as a new cultivation medium for S. obliquus growth in a pilot-scale photo-bioreactor. The investigation revealed key differences between the behavior of the membrane systems at the two scales (bench and pilot). It indicated the potential for beneficial reuse of the permeate stream as the pilot-scale experiments ensured high harvesting performance and growth rates of biomass in permeate water that were highly similar to those recorded in the ideal cultivation medium. Finally, different nutrient reintegration protocols were investigated, revealing that both macro- and micronutrient levels are critical for the success of the reuse approach.

关键词： Scenedesmus obliquus Microfiltration Permeate reuse Harvesting Microalgae Pilot-scale

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Toxic effects of enrofloxacin on

Hongwei QIN, Liufang CHEN, Nan LU, Yahui ZHAO, Xing YUAN

《环境科学与工程前沿（英文）》 2012年第6卷第1期页码 107-116 doi: 10.1007/s11783-011-0327-1

摘要： In this article, the toxic effects of Enrofloxacin (ENFX) on were studied, through investigating the growth, photosynthetic pigments, and protein contents. The possible toxic mechanisms of ENFX were analyzed by determining the superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, proline content, and superoxide anion ( ) generation rate. Results showed that the growth of algae was inhibited by ENFX and the 50% effective concentration (EC ) values for 24, 48, 72, and 96 h of ENFX were 88.39, 63.86, 45.10, and 59.16 mg·L , respectively. After treated with ENFX for 96 h, the contents of photosynthetic pigments decreased with the increase of ENFX concentration, the content of soluble protein and the activity of SOD increased and then decreased, and the generation rate of superoxide anion ( ) increased continually. The contents of MDA and proline changed little in lower ENFX concentration groups, but increased rapidly when treated with higher concentration groups. These results suggested that ENFX affected the growth of , and the main toxicity mechanism was that algal cells generated the reactive oxygen species under ENFX stress, and then the reactive oxygen species (ROS) induced the oxidation damages of biologic macromolecules and changed the biomembrane permeability further.

关键词： enrofloxacin Scenedesmus obliquus toxic effects

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Comparison of growth and lipid accumulation properties of two oleaginous microalgae under different nutrient conditions

Qiao ZHANG,Yu HONG

《环境科学与工程前沿（英文）》 2014年第8卷第5期页码 703-709 doi: 10.1007/s11783-014-0649-x

摘要： This study compared the growth and lipid accumulation properties of two oleaginous microalgae, namely, sp. LX1 and sp. HQ, under different nutrient conditions. Both algal species obtained the highest biomass, lipid content and lipid yield under low-nutrient conditions (mBG11 medium). The biomass, lipid content and lipid yield of sp. LX1 were 0.42 g·L , 22.5% and 93.8 mg·L , respectively. These values were relatively higher than those of sp. HQ (0.30 g·L , 17.1% and 51.3 mg·L , respectively). These algae were then cultivated in an SE medium that contained more nutrients; as a result, the biomass and lipid yield of sp. LX1 reduced more significantly than those of sp. HQ. Opposite results were observed in lipid and triacylglycerols (TAGs) contents. The cell sizes of both algal species under low-nutrient conditions were larger than those under high-nutrient conditions. sp. HQ cells did not aggregate, but sp. LX1 cells flocculated easily, particularly under low-nutrient conditions. In summary, low-nutrient conditions favour the growth and lipid production of both algae, but sp. LX1 outperforms sp. HQ.

关键词： Scenedesmus sp. LX1 Chlorella sp. HQ growth rate algal biomass lipid accumulation triacylglycerols (TAGs)