Seawater-to-Biomass: The Process and Mechanism of Efficiently Producing Limnetic Algal Biomass with Seawater and Wastewater

Haiyan Pei

Abstract

Microalgae are considered a promising feedstock for biofuel, but expansion of algal lipid production commercially is still on its way, blocking by its demand on chemical nutrients and freshwater. Inexhaustible seawater, with a little wastewater added, has great potential to optimize microalga production so that biodiesel production can thrive cost-effectively and sustainably. In comparison to regular medium, limnetic Chlorella SDEC-18 achieved fast growth, high lipid content, enlarged cells, fragile cell walls and efficient settling in this cultivation method referring seawater, together with anaerobically digestion effluent of kitchen waste. Among these advantages of lipid yield and extraction, the response of microtubles to salinity critically contributed to the regulation of carbon metabolites. In detail, osmotic stress depolymerized microtubule, followed by delocating cellulose synthase, which redirected carbon flow to lipid rather than starch or cellulose. Hence, the algal cells cultured in saline environments exhibited superiorities on lipid production and extraction showing as higher than 60% in lipid content and 80% in first extraction efficiency. The promoted settling behavior saved harvest energy input and was resulted from ions in seawater and extracellular polymeric substances secreted by algae. After clarifying the advantages of algal biomass produced from seawater, the follow-up research includes construct a transcriptomics and metabolomics network of algae in salinity ambience for concisely understanding algal cell metabolism and foundating the elaborate control of lipid synthesis in different conditions. Eventually, a scale-up process for algal biomass production could be established with the goal of sustainable and economic biodiesel generation.