KMID : 1094720150200040760
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Biotechnology and Bioprocess Engineering 2015 Volume.20 No. 4 p.760 ~ p.765
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Influence of light conditions of a mixture of red and blue light sources on nitrogen and phosphorus removal in advanced wastewater treatment using Scenedesmus dimorphus
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Zhang Shan
Kim Tae-Hyeong Han Thi Hiep Hwang Sun-Jin
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Abstract
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The effects of several light conditions (various light/dark cycles, light intensities, and light frequencies) of a mixture of intermittent red and blue light on nitrogen and phosphorus removal from wastewater using Scenedesmus dimorphus were evaluated. The nitrogen removal rates were almost the same (~ 10 mg/L/day) during light/dark cycles of 16:8, 20:4, and 24:0, and were two-fold higher than those observed during light/dark cycles of 12:12 and 8:16. The phosphorous removal rate also reached its highest value (~ 1.5 mg/L/day) during the light/dark cycles of 20:4 and 24:0. These results suggest that microalgae should be illuminated for at least 16 and 20 h for the efficient removal of nitrogen and phosphorous, respectively. Moreover, both the nitrogen and phosphorous removal rates were significantly enhanced when the light intensity was raised from 50 to 400 ¥ìmol/m2/sec. Increasing the light intensity above 400 ¥ìmol/m2/sec caused photo-inhibition, such that microalgae production decreased. Besides the light/dark cycle and light intensity, flashing frequency also controls the growth and nutrient removal rate of Scenedesmus dimorphus. It was found that the most appropriate flashing frequency was 2,500 Hz.
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KEYWORD
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microalgae, Scenedesmus dirmorphus, wastewater treatment, nitrogen removal, phosphorus removal, light source
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