"Extremophiles are microorganisms which can thrive in extreme conditions such as either high or low temperature, pressure, salt concentration, alkaline/acidic, etc. These extremophiles may be harnessed for their applications in extreme conditions where normal microorganisms fail to survive. Extremophiles may play an important role in wastewater treatment, biorefining of algal biomass, industrial waste effluent, etc. These microorganisms may be helpful in wastewater treatment for energy generation, electricity generation through microbial electrolysis, etc. There are varieties of microalgae, which have ability to grow under extreme conditions such as acidic, alkaline, saline, high temperature, high CO2 level and minerals, etc. Such microalgae have potential in biorefinergy for the production of biofuels and value-added products. Biorefinery is an integration of processes for generating more than one product to make the process economically and environmentally sustainable. Moreover, the extremophiles have the capability to act on different wastes efficiently under extreme conditions. This book covers the applications of extremophiles for the production of value-added products, including biofuels, extremozymes, wastewater treatment, electricity generation, biofilms, microbial corrosion, etc"--