Chapter 9 - Life cycle assessment of microalgal biomass for valorization

Abstract

The microalgae biorefinery is a promising technical approach to overcome the constant environmental threats caused by anthropic action. Microalgae are a valuable feedstock for diverse purposes, such as bioenergy, biofertilizers, pigments, nutraceuticals, and animal feed, depending on their composition. These microorganisms have high versatility and a vital capacity for environmental remediation, given their ability to thrive in inhospitable environments and adaptability to different cultivation conditions, such as wastewater. However, efforts are still needed to make bioproducts based on biomass produced in wastewater competitive from an environmental, economic, and social perspective compared to other energy sources and nutrients. For environmental analysis, life cycle assessment (LCA) is a strategic tool that allows the mapping of inputs and outputs of materials and residues in the life cycle of a product or process. Therefore it assists in decision-making on the processes to be improved. In the context of the valorization of microalgal biomass, LCA is very recent. This chapter presents the common points, the divergences, the challenges, and opportunities for applying the LCA in valorization routes of microalgal biomass grown in wastewater. It addresses energetic, macro, and micronutrient recovery routes in light of LCA. Besides the essential steps of each route, the main uncertainty and sensitivity analysis will be listed and discussed. Also, suggestions for the standardization of future work, subsidizing comparisons between routes, obtaining products with the same function are put forth.