Maximum microalgae biomass harvesting via flocculation in large scale photobioreactor cultivation

Abstract

AbstractThis study evaluated the ability of Tanfloc SG flocculation to recover microalgae biomass cultivated in a tubular photobioreactor using swine wastewater effluent as the culture media in a pilot‐scale microalgae production plant. The objective function was the flocculation efficiency (ηf), which was evaluated by central composite design (CCD) experiments which varied the Tanfloc concentration (TC) and pH. Subsequently, the biomass recoveries of highly efficient flocculants recommended by the literature and the CCD conditions of Tanfloc were compared. The maximum flocculation efficiency (96.7 ± 1.0 %) was obtained for the following optimal conditions: 210 mg/L Tanfloc concentration, pH 7.8. After jar test experiments, the scale‐up of the process was performed by using the best obtained results and applying Tanfloc in a 1 m3 flocculator where the complementary analyses demonstrated efficient nitrogen, carbon, and biomass removal. The flocculation efficiency obtained with Tanfloc was equivalent to that of most conventional flocculants currently used. However, Tanfloc presented the following economic advantages with respect to other flocculants: i) its nontoxic nature allows for low‐cost disposal; and ii) its low market price makes it a promising alternative for harvesting microalgae biomass.