Microalgae are recognized as sustainable bioresources due to their high productivity, fast growth rates, and ability to sequester carbon dioxide while pretreating wastewater, their ability to thrive in diverse environments, and potential for biotechnological applications. Wastewater not only serves as a cost-effective medium but also provides an abundance of nutrients favorable for algal growth. It offers a nutrient-rich medium for microalgal cultivation, contributing not only to biomass production but also to wastewater bioremediation. Culture-based methods involve isolation and identification of microalgal strains from industrial, municipal, and agricultural wastewater sources using different isolation approaches. This study explores the diversity of microalgae cultivated in different wastewater environments, emphasizing the integration of both cultured and uncultured approaches to gain a comprehensive understanding of their community structure and functional potential. In conclusion, this work emphasizes the immense ecological and biotechnological potential of microalgae grown in wastewater. The incorporation of both cultured and uncultured approaches proved essential in unraveling the complex diversity and enhancing the prospect of harnessing robust microalgal strains for environmental and industrial applications. Future directions include metagenomic and metatranscriptomic studies to further explore the functional roles and metabolic capabilities of these diverse microalgal communities.