Influence of Nitrate Feeding on Carbon Dioxide Fixation by Microalgae

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Vol. 41; no. 12; pp. 2813 - 2824
• Main Authors: JIN, HAI-FENG, LIM, BYUNG-RAN, LEE, KISAY
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 01.12.2006
• Subjects: Algae; Bioreactors; Carbon; Carbon - metabolism; Carbon dioxide; Carbon Dioxide - metabolism; Chlorella; Chlorophyta - growth & development; Chlorophyta - metabolism; Cyanobacteria; Cyanobacteria - metabolism; Feeding; Fixation; Green algae; Microcystis; Microcystis aeruginosa; Microcystis ichthyoblabe; Nitrate feeding; Nitrates; Nitrates - metabolism; Photobioreactor; Scenedesmus; Strategy
• ISSN: 1093-4529; 1532-4117
• DOI: 10.1080/10934520600967928

In this study, the effects of nitrate feeding on microalgal growth and associated CO 2 fixation were evaluated, as a strategy to enhance carbon fixation by increasing the duration of the exponential phase of cell growth in the batch operation of a photobioreactor. Two species of green algae, Chlorella and Scenedesmus, and two species of cyanobacteria, Microcystis ichthyoblabe and Microcystis aeruginosa, were used after adaptation to a 15% (v/v) CO 2 environment. In the absence of nitrate feeding, nitrate concentrations declined rapidly and soon became a limiting factor. Nitrate feeding, administered in fed-batch mode to maintain 15-20 ppm of NO 3 -N, allowed for an extension of the exponential growth phase by more than 3 days, as well as a higher cell density, which subsequently resulted in an increase in photoautotrophic carbon fixation. The increases in the carbon fixation rate were in the ranges of 56.1-56.6% for the green algae, and between 68.2-68.8% for the cyanobacteria. The results indicated that intermittent nitrate feeding was a viable strategy for the augmentation of fixation productivity, and may thus be effectively applied as a substitute for conventional medium change, which has traditionally been employed in order to prolong the active growth duration.