The circular economy approach was exploited in this study to exploit a waste produced from the anerobic digestion of organic waste, such as digestate to the final production of microalgae. This biomass production was realized sequestering CO2 from air. The digestate originated from a dry anaerobic digestion pilot plant of the OFMSW located at the Fondazione Edmund Mach (S. Michele a/A, Trento, Italy), details are reported elsewhere [1,2]. The microalgae growth experiment was performed in a 15 L laboratory scale system. 13 L of diluted digestate were incubated; to ensure aerobic conditions, the digestate was continuously fluxed with air for 5 days. After this incubation, algae inoculum was added to digestate. A common green algae Chlorella vulgaris (strain Chlorella cf vulgaris K-1801 SCAAP-DK) was used as inoculum. This microalgae was initially grown on Algal Broth culture medium 25 °C with a 14:10 light:dark cycle with 50 µmol m−2 s–1 measured at the culture surface using a Quantum PhotoRadiometer (Delta Ohm srl, Caselle di Selvazzano, PD, Italy). Algal cells were harvested by gentle centrifugation and washed twice with distilled water before inoculation to insure no nutrient carryover. The microalgae were grown in controlled conditions in 15 L laboratory scale system. The temperature was maintained at 25 °C and the 12:12 dark/light cycle (7.00 a.m. – 7.00 p.m.) was guaranteed with Lucalox psl (LU400W/PSL/T/E40) at 400 watts with 65-µmol m2-1sec-1 of photosynthetically active radiation (PAR). The algae inoculum was diluted in 2 L of distilled water and then added to the digestate medium for a final concentration of 20% v v-1. Two trials were performed: Laboratory Scaled digestate (LSd -without CO2 addition) and LSCO2 (with CO2 addition). The control consisted of flasks with tap water without nutrient addition (Cw). The supply of carbon dioxide was controlled via CO2 mass flow (bronkhorst, NL) to maintain the CO2-to-ambient air ratios of 0.035% v/v. Moreover, the flux of CO2-air guaranteed a continuous mixing of the medium. The feed flow gas rate was 0.2 vvm of the enclosed laboratory scale system (LSCO2), while the test without CO2 addition (LSd) was performed in the open laboratory scale system and mixed without aeration and CO2 supply. Microalgal growth was determined through cell counts using a Fuchs-Rosenthal chamber slide and counting through microscope at 10 X and 20 X magnifications to determine cell concentration. Every three days, 0.5 ml of growth medium was sampled diluted with 3 ml of distilled water and fixed with Lugol. To calculate biovolume, at least 400 algal cells were counted, and separated by the size of the cells. The optical density usually used to evaluate growth could not be applied in our case due to the color of digestate and to potential changes during the experiment.

Microalgae production from digestate of dry anaerobic digestion of organic waste sequestering CO2 from air / Papurello, Davide; Bona, Daniela; Tomasi, Luca; Flaim, Giovanna; Cerasino, Lorenzo; Silvestri, Silvia. - ELETTRONICO. - (2019), pp. 88-90. ((Intervento presentato al convegno Mater 19 tenutosi a Piacenza nel maggio 2019.

Microalgae production from digestate of dry anaerobic digestion of organic waste sequestering CO2 from air.

Davide Papurello;
2019

Abstract

The circular economy approach was exploited in this study to exploit a waste produced from the anerobic digestion of organic waste, such as digestate to the final production of microalgae. This biomass production was realized sequestering CO2 from air. The digestate originated from a dry anaerobic digestion pilot plant of the OFMSW located at the Fondazione Edmund Mach (S. Michele a/A, Trento, Italy), details are reported elsewhere [1,2]. The microalgae growth experiment was performed in a 15 L laboratory scale system. 13 L of diluted digestate were incubated; to ensure aerobic conditions, the digestate was continuously fluxed with air for 5 days. After this incubation, algae inoculum was added to digestate. A common green algae Chlorella vulgaris (strain Chlorella cf vulgaris K-1801 SCAAP-DK) was used as inoculum. This microalgae was initially grown on Algal Broth culture medium 25 °C with a 14:10 light:dark cycle with 50 µmol m−2 s–1 measured at the culture surface using a Quantum PhotoRadiometer (Delta Ohm srl, Caselle di Selvazzano, PD, Italy). Algal cells were harvested by gentle centrifugation and washed twice with distilled water before inoculation to insure no nutrient carryover. The microalgae were grown in controlled conditions in 15 L laboratory scale system. The temperature was maintained at 25 °C and the 12:12 dark/light cycle (7.00 a.m. – 7.00 p.m.) was guaranteed with Lucalox psl (LU400W/PSL/T/E40) at 400 watts with 65-µmol m2-1sec-1 of photosynthetically active radiation (PAR). The algae inoculum was diluted in 2 L of distilled water and then added to the digestate medium for a final concentration of 20% v v-1. Two trials were performed: Laboratory Scaled digestate (LSd -without CO2 addition) and LSCO2 (with CO2 addition). The control consisted of flasks with tap water without nutrient addition (Cw). The supply of carbon dioxide was controlled via CO2 mass flow (bronkhorst, NL) to maintain the CO2-to-ambient air ratios of 0.035% v/v. Moreover, the flux of CO2-air guaranteed a continuous mixing of the medium. The feed flow gas rate was 0.2 vvm of the enclosed laboratory scale system (LSCO2), while the test without CO2 addition (LSd) was performed in the open laboratory scale system and mixed without aeration and CO2 supply. Microalgal growth was determined through cell counts using a Fuchs-Rosenthal chamber slide and counting through microscope at 10 X and 20 X magnifications to determine cell concentration. Every three days, 0.5 ml of growth medium was sampled diluted with 3 ml of distilled water and fixed with Lugol. To calculate biovolume, at least 400 algal cells were counted, and separated by the size of the cells. The optical density usually used to evaluate growth could not be applied in our case due to the color of digestate and to potential changes during the experiment.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11583/2782135