# Microalgal Biomass Generation via Electroflotation: A Cost-Effective Dewaring Technology
###### Abstract  
Microalgae are an excellent source of bioactive compounds for the production of a wide range of vital consumer products in the biofuel, pharmaceutical, food, cosmetics, and agricultural industries, in addition to huge upstream benefits relating to carbon dioxide biosequestration and wastewater treatment. However, energy-efficient, cost-effective, and scalable microalgal technologies for commercial-scale applications are limited, and this has significantly impacted the full-scale implementation of microalgal biosystems for bioproduct development, phycoremedian, and biorefinery applications. Microalgae culture dewatering continues to be a major challenge to large-scale biomass generation, and this is primarily due to the low cell densities of microalgal cultures and the small hydrodynamic size of microalgal cells. With such biophysical characteristics, energy-intensive solid-liquid separation processes such as centrifugation and filtration are generally used for continuous generation of biomass in large-scale settings, making dewatering a major contributor to the microalgae bioprocess economics. This article analyzes the potential of electroflotation as a cost-effective dewatering process that can be integrated into microalgae bioprocesses for continuous biomass production. Electroflotation hinges on the generation of fine bubbles at the surface of an electrode system to entrain microalgal particulates to the surface. A modification of electroflotation, which combines electrocoagulation to catalyze the coalescence of microalgae cells before gaseous entrainment, is also discussed. A technoeconomic appraisal of the prospects of electroflotation compared with other dewatering technologies is presented. microalgae; dewatering; electroflotation; biomass; scale-up; process economics +
Footnote †: journal: Applied Sciences  
18 November 20202014 December 20202018 December 2  
(United States), the global compound annual growth rate (CAGR) of microalgae between the year 2017 and 2026 is estimated at 4.6% [8]. Furthermore, it is estimated that the revenue from the global sales of microalgae will exceed USD 75 million by the end of the year 2026 [9]. Europe was identified as the largest market for microalgae-based products in 2019, followed by North America, Asia Pacific, Latin America, Middle East, and Africa [10; 11]. Microalgal products have been mostly used in food and beverage industries, followed by animal feed, nutraceutical, and dietary supplements, fuel, personal care, pharmaceutical, chemical or pigment and fertilizer industries [12]. Even though microalgae are highly beneficial for the global economy, energy-efficient, cost-effective and scalable microalgal technologies for commercial-scale applications are limited, and this has significantly impacted the full-scale implementation of microalgal biosystems for bioproduct development, phycoremmediation, and biorefinery applications [13]. In general, microalgal culture is developed by the inoculation of microalgal species into a nutrient-rich culture medium, and can be maintained at ambient conditions (15-30 \({}^{\circ}\)C in the presence of carbon dioxide) to allow growth followed by harvesting [14]. After harvesting, dewatering and drying processes are required to generate biomass for product development. The presence of water in the microalgal biomass after harvesting affects the efficiency of the extraction technique as well as the concentration and characteristics of value-added extracts. Microalgae culture dewatering continues to be a major challenge to large-scale biomass generation, and this is primarily due to the low cell densities of microalgal cultures and the small hydrodynamic size of microalgal cells [15]. With such biophysical characteristics, energy-intensive solid-liquid separation processes such as centrifugation and filtration are generally required for continuous generation of biomass in large-scale settings, making dewatering a major contributor to the microalgae bioprocess economics [16].