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Environmental and energy security has now become a serious global problem, requiring a lot of research to find and implement its cost-effective and environmentally friendly alternatives. The development and use of renewable energy sources is necessary and important in order to avoid the emergence of a global economic crisis. One of the solution to prevent a future crisis caused by energy shortages is to introduce biofuels into the fuel market. Despite the fact that various forms of renewable energy are currently used, the prospects for the production of biofuels from cyanobacteria are quite high due to their unique properties, such as a high lipid content and a suitable fatty acid (FA) composition for the production of biofuels, their suitability for growing open water and the ability to grow on wastewater. The purpose of this article is to provide a comprehensive overview of the potential of cyanobacteria in the conversion of wastewater into biofuels. The article covers comparative data on the accumulation of lipids and the content of fatty acids in various representatives of cyanobacteria and their possibilities in the remediation of wastewater. Various approaches to the extraction of lipids from phototrophic microorganisms that are currently available, their advantages and disadvantages, and the results of the monitoring of the main key points of the development of the technology for converting cyanobacterial biomass into biofuels, with an emphasis on the existing barriers, effects and solutions, are also considered. Further research in this field is required for the successful implementation of this technology on an industrial scale. [ABSTRACT FROM AUTHOR]

Following the circular bioeconomy approach, this study shows the possibility of effective microalgal bioremediation of aquaculture wastewater integrated with the production of protein-rich biomass, which can be used as a feed additive. Screening was carried out among strains of Chlorella vulgaris BB-2, Parachlorella kessleri Bh-2 and Chlamydomonas reinhardtii C-124 with the aim of selecting the strain which is characterized by high indicators of growth in the fish farms wastewaters. Among these three strains, C. vulgaris BB-2 was selected due to its increased growth rate in aquaculture wastewater with ammonia, nitrite, and nitrate and phosphate removal. In addition, in the water when cultivating microalgae in it the coliform index and total microbial number decreased to 5 and 1.8 × 103 colony-forming unit cm−3. Large-scale microalgae cultivation utilizing aquaculture wastewater gave biomass production of 43.5 mg L−1 day−1. The biochemical composition analysis of the aquaculture wastewater phycoremediation-derived biomass of C. vulgaris BB-2 revealed that the content of 57.0 ± 1.2% protein, 16 ± 1.2% lipid, and 11.4 ± 1.4% carbohydrate. The obtained data indicate that the lipid extract of microalgae C. vulgaris BB-2 contained saturated 30.7% and polyunsaturated fatty acids 69.3%. The main fraction of amino acids consisted of glutamic acid, lysine, aspartic acid and leucine. The utilization of 25% microalgal biomass as a feed additive in the diet of fish has shown a positive effect on the morpho-physiological and biochemical growth parameters and intestinal microflora of Nile tilapia (Oreochromis niloticus). [ABSTRACT FROM AUTHOR]