Influencia de la Fase Acuosa de Carbonización Hidrotermal en la Biofijación de CO2 en microalgas

Abstract

This study evaluated the influence of the aqueous phase (AP) of hydrothermal carbonization (HTC) and activator as nutrients on the productivity and biosequestration of CO2 in Chlorella sp. microalgae. To optimize the addition of nutrients, the Response Surface Methodology (MSR) was used. The functional groups of the cultured microalgae were analyzed by infrared spectroscopy and elemental analysis. For AP, pH and conductivity were measured with a multiparameter, chemical oxygen demand (COD) using the colorimetric potassium dichromate method, biological oxygen demand (BOD) by the metric respite method, analysis of cellobiose, glucose, xylose, lactic acid and acetic acid by high efficiency liquid chromatography, total nitrogen by Kjeldhal (NTK), total phosphorus (PT) by the colorimetric method and, metals traced by atomic absorption spectrophotometry. The effect on biosequestration was determined between 5-30% (v/v) of CO2. Optimal nutrient levels were 0,2 gL-1 activator and 1,317% AP. The AP presented a pH of 4,7, COD of 4553,3 mg/LO2, BOD of 1300 mg/LO2, low conductivity values, PT, lactic acid, xylose, and trace metals, without detection of acetic acid, glucose, celobiose and NTK. The maximum biosequestration was 71 mgL-1d-1 and the highest biomass concentration was 0,402 gL-1 which were determined at 15% CO2. A higher proportion of lipids, carbohydrates and lower proportion of proteins were identified in the biomass of Chlorella sp. making it profitable for gaining biofuels. Finally, it was concluded that the AP although sustainable, did not significantly influence the productivity and biosequestration of CO2 in the microalgae, except for the activator. It is recommended to use different experimental points around the optimal nutrients to differentiate better results of the effect of AP on biosequestration.