Integrated Wastewater Treatment and Biofuel Production Using Microalgae

Abstract

Several wastewaters contain many nutrients such as carbon, nitrogen, and phosphorus that microalgae can consume for their biomass development. Microalgae are superior to other species, as they can tolerate the toxic environment and fluctuating pollutant levels of the wastewater. The microalgal biomass can be further used to produce third-generation biofuels, namely, biochar, bio-oil, biogas, and several other value-added products. They can store high lipid and sugar content depending on the species. The dual role of microalgae to treat wastewater and produce biofuel plays a significant role in reducing the overall cost of the process. This chapter highlights different wastewaters that various microalgal species have treated, such as municipal, agricultural, and industrial. Further, various biological methods such as anaerobic digestion, fermentation, and thermochemical processes such as pyrolysis, hydrothermal liquefaction, torrefaction, gasification, and transesterification, convert microalgal biomass into biofuels have also been discussed, including their mechanisms and operating conditions. The properties and applications of the biofuels formed from different processes have also been discussed. Later, some important applications of the various biofuels have also been discussed. Lastly, a brief discussion of life cycle assessment and techno-economic analysis from the previous studies, along with the current policies, have been discussed to check the economic and environmental viability of the microalgal fuels.