A Holistic Approach to Managing Microalgae for Biofuel Applications

Abstract

Microalgae contribute up to 60% of the oxygen content in the Earth’s atmosphere by absorbing carbon dioxide and releasing oxygen during photosynthesis. Microalgae are abundantly available in the natural environment, thanks to their ability to survive and grow rapidly under harsh and inhospitable conditions. Microalgal cultivation is environmentally friendly because the microalgal biomass can be utilized for the productions of biofuels, food and feed supplements, pharmaceuticals, nutraceuticals, and cosmetics. The cultivation of microalgal also can complement approaches like carbon dioxide sequestration and bioremediation of wastewaters, thereby addressing the serious environmental concerns. This review focuses on the factors affecting microalgal cultures, techniques adapted to obtain high-density microalgal cultures in photobioreactors, and the conversion of microalgal biomass into biofuels. The applications of microalgae in carbon dioxide sequestration and phycoremediation of wastewater are also discussed.

Algal Biomass from Wastewater and Flue Gases as a Source of Bioenergy

“…Biomass gasification is a thermochemical conversion process occurring at temperatures above 375 • C and pressure above 20 MPa under a controlled amount of oxygen. The limited amount of oxygen leads to an incomplete combustion of the biomass, resulting in the production of combustible gases like CO, H 2 , and low molecular weight hydrocarbon gases [174,191,192]. There is a great variation in the yield and the composition of the different gases produced by algal biomass gasification [193].…”

“…Due to its chemical structure, the energy content of biobutanol is higher than that of bioethanol. Algal biomass can be used to produce biobutanol via bacterial fermentation of carbohydrate-rich biomass [221][222][223]; the most commonly used are bacteria of the genus Clostridium [192,193]. Biobutanol has been produced from algae grown in wastewater, e.g., Neochloris aquatic grown in swine wastewater [221,222].…”

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products

“…Mixing and aerating provide uniform distribution of nutrients, air, and CO 2 in microalgae culture. They also enable the penetration and uniform distribution of light inside the culture and prevent the biomass from settling and causing aggregation [ 94 ]. If all the other requirements are met but there is no mixing, biomass productivity will be lowered significantly.…”

A review on microalgae cultivation and harvesting, and their biomass extraction processing using ionic liquids

“…This cultivation system got its name from its circularshaped culture tank, and typically have the depth of 30-70 cm and width of 45 m along with a rotating agitator located at the center of the pond [14]. The rotating agitator is being used to ensure efficient mixing and prevent sedimentation of algae biomass [15]. However, the design of this cultivation system is limited by its size since bigger pond might introduce stronger water resistance, and therefore causes strain on the mechanical parts of agitator [16].…”