Microalgal-Bacterial Biomass System for Wastewater Treatment: A Case Study on Real Wastewater Treatment

Microalgae represent all photosynthetic prokaryotic and eukaryotic microorganisms. Cyanobacteria, previously known as blue-green algae, are prokaryotic, not eukaryotic like other algal groups. Since they are photosynthetic, their production systems are the same as those of microalgae. Microalgae and cyanobacteria form phytoplankton. Since they are used as nutrients for fish and other aquatic organisms, they form the starting point of the food chain in nature. As a result of increasing environmental sensitivities, developments in treatment technologies continue. Because the excess nitrogen, phosphorus, and other nutrients in wastewater that are left in the receiving environment without treatment cause eutrophication and harm the environment. Wastewater containing abundant mineral substances can be a suitable development environment for aquatic plants, microalgae, and cyanobacteria (blue-green algae) if environmental conditions such as light and temperature are regulated. With this type of treatment process, wastewater is treated, and new products can be commercialized. Biomass is obtained by growing microalgae in wastewater. In addition to its use in environmental biotechnology applications such as biofuel, biojet fuel, biofertilizer, and animal feed production, it also finds use in medicine, food, pharmacy, textiles, and cosmetic technologies. While feeding microalgae with wastewater contributes economically to increasing the efficiency of treatment, such wastewater treatment systems, which can generate income by producing microalgae cultures, have become an important option. Feeding microalgae with wastewater not only contributes economically to increasing the efficiency of treatment but also has become an important option for this purpose among such wastewater treatment technologies that generate income by producing microalgae cultures. So, the main purpose of this book chapter is to examine in all detail the studies in the literature on the conversion of cyanobacteria in the microalgae-bacterial biomass-based system into either an energy source or soil-improving fertilizer and commercialization while removing pollutants from domestic wastewater. In this sense, this chapter first reviews the recent developments in microalgae-cyanobacteria-based systems for wastewater pollution control, then discusses the biosorption and bioaccumulation mechanisms of pollutants by cyanobacteria, factors affecting microalgae-cyanobacteria systems and developments and innovative designs on photobioreactors. Finally, the removal efficiency of pollutants from wastewaters by microalgae, which is widely found in receiving waters such as lakes or river flora, was evaluated within the scope of a case study carried out in the literature. According to the case study results, microalgal-cyanobacteria-based technology was assessed in terms of both an effective and low-cost advanced treatment of municipal wastewater and also an alternative energy source or soil-improving fertilizer usage after harvest as biomass-based. © 2025 selection and editorial matter, Maulin P. Shah and Günay Yıldız Töre.