Evaluation of an outdoor mass culture system of the marine microalga Nannochloropsis oculata, in a temperate oceanic region of Argentina.

PERSICO, MM; MORIS, M; TRANIER, E; ZANAZZI, N; SAUBIDET, AA; BELIGNI, MV

Revista de la Sociedad Latinoamericana de Biotecnologica Ambiental y Algal (RELBAA)

RELBAA

Año: 2011 vol. 2 p. 30 - 48

2007-2570

The UTN has a scientific interdisciplinary program focused on the development of processes, environmentally and economically sustainable, for the mass culture of microalgae for biodiesel generation. This program involves a replacement of high cost consumables by making use of environmental liabilities, such as industrial waste and sewage sludge. In addition, it is focused on the use of marine microalgae with the idea of conserving drinking water. For this purpose, we have established a system for the provision and treatment of marine water coming for the refrigeration of a nearby thermoelectric power plant. At a first stage, we evaluated the culture of Nannochloropsis oculata, selected by its high oil content, at a production facility made with simple, low cost materials. With light and temperature imposed by the environmental conditions, we have cultured N. oculata in the four seasons. For a whole year, we have monitored environmental (temperature, illuminance) and culture (pH, salinity, temperature) parameters. The pH was regularly controlled to values between 7.5 and 8.0 and the salinity within the range of 28-30 ?. In addition, maximum and average cell densities and duplication rates were determined. Both parameters reached their maximum values in spring, followed by winter and autumn, whereas the high temperatures of the summertime produced the lowest values. The greenhouse was useful at protecting the cultures from extremely low temperatures, but produced a significant filtration of the solar rays during the months with the lowest light fluxes. This was probably the reason for the reduced cell densities in the greenhouse during the wintertime. When comparing cultures of identical volumes (1,500 liters), we evidenced that rectangular tanks (raceway) produced maximum cell densities 15 to 20 % higher than circular tanks. In summary, we gained highly valuable information that enabled us to establish basic processes for the mass culture of N. oculata that yield productivities suitable for biodiesel generation. Possible improvements and future lines of research are proposed.