Microalgae flocculation: Impact of flocculant type, algae species and cell concentration

Harvesting Microalgal Biomass grown in Anaerobic Sewage Treatment Effluent by the Coagulation-Flocculation Method: Effect of pH

“…In a study by Teixeira et al 13 ,C. vulgaris biomass recovery was 93.8%, applying 1000 mg/L of aluminum sulfate at pH 9.24. Gerde et al 16 applied aluminum sulfate to recover Scenedesmus sp. grown in synthetic medium at an adjusted pH between 8.5 and 9.5.…”

“…); these results corroborate those observed in the current study for MBM removal efficiency using the same dosage and pH ranges. Gerde et al 16 used two types of cationic starch (DS02 and DS05) to harvest Scenedesmus sp. and Chlamydomonas reinhardtii in synthetic medium at pH adjusted between 8.5 and 9.5.…”

“…Unlike inorganic metal salts, biodegradable organic coagulants do not contaminate the recovered biomass, and generally require low application doses, considering a wide pH range. Therefore, coagulants obtained from natural polymers are better alternatives for MBM harvesting than inorganic coagulants 15,16,17 . In this work, aluminum sulfate wasused as the reference coagulant, and natural organic coagulants were obtained from Moringa oleifera seeds, Acacia tannin, Hibiscus esculentus gum and cationic starch and were evaluated for MBM recovery by thecoagulation-flocculation-sedimentation method.…”

Effect of eggshells for the harvesting of microalgae species

“…The lower separation efficiency was most probably caused by the decrease in contact between the cells and the flocculant. [7,29] As the mixing time was increased from 5 to 20 min, the total number of collisions was increased significantly. Similar to the results obtained with other flocculants, [9,29] this could be due to higher probability of cells and eggshell particles to collide with each other, allowing coagulation and adsorption to occur spontaneously.…”

“…[2,4] However, as pointed out by Malm and Tanner [5], harvesting microalgae biomass is challenging mainly due to the small size of microalgae, their tendency to grow as single cells and the low cell density in the culture medium. [6,7] The solution volumes to be treated are large and the amount of processing and energy needed renders the separation of pure microalgae biomass demanding and expensive. It has been calculated that up to 20%À30% of the total production costs are due to the biomass recovery stage.…”