Microbial technologies play an extremely crucial role in wastewater treatment. In the last few decades, the focus was on wastewater treatment; however, with the consumption of already finite resources, this focus has now shifted to wastewater remediation and recycling. The latest technologies are more robust at wastewater treatment and the recovery of useful compounds from the wastewaters. This chapter compiles the latest technologies in which microbial/bacterial biomass was used for wastewater treatment and remediation. This chapter also gives a special focus on remediation of wastewaters contaminated with heavy metals, describing the basic technologies as well as smart technologies. Emphasis is given to circular bioeconomy and how it can be implemented in wastewater treatment. A circular model incorporating key areas such as point source detection of pollutants, characterization of wastewaters, choice of the remedial technology, and type of treatment is explained in the chapter.