AN EXPERIENCE OF OUTDOOR MASS CULTIVATION AND OIL PRODUCTION FROM NANNOCHLOROPSIS OCULATA IN A TEMPERATE OCEANIC REGION OF ARGENTINA

LOSPENNATO, M, PÉRSICO, MM, CHAMORRO, E., ZANAZZI, AN, TRANIER, ED, SEQUEIRA, A, PALOMEQUE, M, BELIGNI MV

Westin, San Diego

Congreso; 2nd International Conference of Algal Biomass, Biofuels & Bioproduct; 2012

We focus on the development of sustainable processes for the outdoor mass culture of microalgae for oil generation in Mar del Plata, an Argentinian town with temperate oceanic climate. We established a system for the provision of marine water coming from the refrigeration of a nearby thermoelectric power plant. We evaluated the culture of Nannochloropsis oculata at a simple, low cost facility in both traditional (Yashima) and residual (sewage sludge) media, aiming to obtain maximum biomass productivities. We have monitored environmental and culture parameters for over three years, being pH and salinity adjusted daily. Maximum productivities were obtained in spring, followed by winter and autumn, whereas the high temperatures of the summertime produced the lowest values. The greenhouse protected the cultures from extremely low temperatures, but produced a significant filtration of the solar rays during the months with the lowest light fluxes. We also optimized a two-stage oil production in which cultures grown in “replete” media (100 mg/l nitrate, 10 mg/l phosphate, 15 mg/l urea) were diluted in marine water with reduced amount of media. The best results were obtained when 25-30% (v/v) of the culture was diluted using between 1/8 and no replete media, achieving 20-55% (w/w) oil/dry biomass after 5-8 days. Several oil extraction methods easily transferable to the industrial sector were evaluated: cold extraction (batch using hexane and Bligh and Dyer) and hot extraction (hexane in soxhlet) on either dry biomass powder or paste carrying 50% humidity. The efficiency of the methods was valued using TLC and GC; the fatty acid profile was determined by GC-MS. Maximum extraction was obtained using hexane in soxhlet starting from biomass dried at 100 °C, but with a marked decomposition of C20:5 (EPA). Other methods showed a lower amount of extractive material, but with a higher proportion and quality of triglycerides.Nannochloropsis oculata at a simple, low cost facility in both traditional (Yashima) and residual (sewage sludge) media, aiming to obtain maximum biomass productivities. We have monitored environmental and culture parameters for over three years, being pH and salinity adjusted daily. Maximum productivities were obtained in spring, followed by winter and autumn, whereas the high temperatures of the summertime produced the lowest values. The greenhouse protected the cultures from extremely low temperatures, but produced a significant filtration of the solar rays during the months with the lowest light fluxes. We also optimized a two-stage oil production in which cultures grown in “replete” media (100 mg/l nitrate, 10 mg/l phosphate, 15 mg/l urea) were diluted in marine water with reduced amount of media. The best results were obtained when 25-30% (v/v) of the culture was diluted using between 1/8 and no replete media, achieving 20-55% (w/w) oil/dry biomass after 5-8 days. Several oil extraction methods easily transferable to the industrial sector were evaluated: cold extraction (batch using hexane and Bligh and Dyer) and hot extraction (hexane in soxhlet) on either dry biomass powder or paste carrying 50% humidity. The efficiency of the methods was valued using TLC and GC; the fatty acid profile was determined by GC-MS. Maximum extraction was obtained using hexane in soxhlet starting from biomass dried at 100 °C, but with a marked decomposition of C20:5 (EPA). Other methods showed a lower amount of extractive material, but with a higher proportion and quality of triglycerides.