Abstract

MORENO, L. M; MUNOZ PRIETO, E  and  CASANOVA, H. Flocculatin with Chitosan of Microalgae Native of the Colombian Plateau. Ciencia en Desarrollo [online]. 2015, vol.6, n.1, pp.17-24. ISSN 0121-7488.

Microalgae are an attractive feedstock for biofuel production. Low harvesting cost upholds the use of flocculation as initial dewatering step. Two freshwater microalgae (Chlorell a sp. and Scenedesmus sp.) native from the Colombian plateau, with low/medium biomass concentrations, were selected for this study. The effects of pH, Z-potential and flocs size in dictating the behavior of chitosan as flocculant, were evaluated. This study found that the optimal flocculation efficiency of microalgae was determined at pH 7.0; besides the zeta-potential was positively correlated with the flocculant dose. The zeta-potential increases positively with a flocculant dose. The Chlorella sp. is smaller than the Scenedesmus sp. but requires a little more dose of flocculant; this aspect is due to the nature of the flocculant solution and not the size of the studied microalgae. It was observed that for Chlorella sp., chitosan coagulation shifted the flocs size from 2-4 µm to 70-80 µm, with 1.0 ml of the 40 ppm chitosan solution. The flocculation with chitosan can yield compact flocs and accelerate the settling. For Scenedesmus sp. the flocs size was shifted from 3-4 µm to 60-70 µm and less percentage in the flocs volume. Flocculation response of the microalga Scenedesmus sp. is different in comparison to that of Chlorella. The flocculant dose required is greater, although the percentage of flocculation is also higher and the flocs size is only slightly larger. Further work is needed to confirm these observations.

Keywords : Flocculation; Microalgae; Chitosan; Z-Potential.

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