growth of Chlamydomonas reinhardtii as influenced by high CO2 and low O 2 in flue gas from a silicomanganese smelter

• Published in: Journal of applied phycology 2015-04, Vol.27 (2), p.633-638
• Main Authors: Mortensen, Leiv M, Gislerød, Hans R
• Format: Article
• Language: English
• Subjects: air; biomass; carbon dioxide; Chlamydomonas reinhardtii; culture media; growth retardation; microalgae; nitric oxide; oxygen; pollutants; seaweed culture; sulfur dioxide
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-014-0357-8

The aim of this study was to find an inexpensive and environmentally friendly CO₂source for growing the hydrogen-producing microalgae Chlamydomonas reinhardtii. The effect of different flue gas concentrations from a silicomanganese smelter on the growth of these algae at a photon flux density of 200 μmol photons m⁻² s⁻¹applied 24 h day⁻¹was studied. First, the algae were grown in a laboratory at 1.2, 6.8 and 17.1 % (v/v) pure CO₂gas mixed with fresh air. After 5 days of growth, the dry biomass per litre algal culture was slightly higher (17 %) at 6.8 % CO₂as compared to at 1.2 % CO₂. A further increase to 17.1 % CO₂decreased the biomass by about 40 %. Then, the flue gas from a silicomanganese smelter was used as a CO₂source for growing the algae. The flue gas was characterized by a high CO₂concentration (about 17 % v/v), low oxygen concentration (about 4 %), about 100 ppm NO ₓ and 1 ppm SO₂. The culture medium bubbled with undiluted flue gas contained about 490 mg L⁻¹dissolved CO₂and 4.0 mg L⁻¹dissolved O₂, while the lowest flue gas concentration contained about 280 mg L⁻¹CO₂and 7.1 mg L⁻¹O₂. Undiluted flue gas (17.4 % CO₂) decreased the biomass of the algae by about 40 % as compared with 4.8 % pure CO₂gas or flue gas diluted to a concentration of 6.3 % CO₂. Flue gas diluted to give 10.0 % CO₂gave less reduction in the growth of the algae (22 %). It was concluded that the high CO₂concentration itself caused the growth reduction and not the air pollutants, and the very low O₂concentrations in the growth medium could not counteract this negative effect.