Microalgae as Bio-fertilizer: a New Strategy for Advancing Modern Agriculture, Wastewater Bioremediation, and Atmospheric Carbon Mitigation

摘要

In this review article, recent contributions of potential uses of microalgae (green and cyanobac-teria) in the agricultural and livestock sector, such as in the production of biofertilizers, biostimulants, and soil conditioning, are presented and discussed. Recent research was compiled to provide information on the productivity in microalgae biomass, dry biomass, and percentages of proteins from microalgae biomass, in addition to the definition of the best models of photo-bioreactors available for the cultivation of over thirty microalgae species. Ideal cultivation conditions, including the use of seven types of wastewaters as a substrate, are presented to show readers the best production routes for this specific type of biomass. Information on improvements in environmental services provided by microalgae cultivation are also included, such as bioremediation of wastewater and recovery of resources, in addition to the biofixation of CO_2, which serves to mitigate air pollution. The bioremediation potential of mixotrophic, heterotrophic, and photoau-totrophic microalgae cultures is demonstrated in the average removals of COD (71.1), BOD, (78.2), NH_4~+ (93.4), and P (88.5) found according to the cited articles. Comparisons between the performance of biomass versus conventional fertilizers are discussed critically and objectively, based on the results of experiments with more than ten crop plants. Furthermore, to fulfill the purpose of this mini review, the research needs for future advancements of modern agriculture using microalgae are highlighted, including assessments on different soil types, plants, and microalgae biomass application methods. Finally, the challenges faced by microalgae biotechnology in expanding its contribution to the bioeconomy are also evaluated, namely, reducing pressure on natural resources, providing innovative agriculture, less dependent on energy inputs, and contributing to the sustainability of the planet.