This is the second volume of a two-volume set book, Electromagnetic Wave Innovations for Sustainability, which explores advancements in electromagnetic technologies like photocatalysis and microwave chemistry for sustainable energy production, recycling, and environmental remediation, within the framework of the SDGs and circular economy. The second volume focuses on applications of electromagnetic-wave–based technologies that address pressing environmental and energy challenges. It opens with a historical overview of microwave technologies for environmental protection and hybrid microwave–photocatalysis systems for wastewater treatment. The next section explore innovations in recycling technologies, including polymer degradation, plastic-to-monomer conversion, biomass–plastic co-recycling for hydrogen and carbon nanomaterials, and microwave-induced pyrolysis for metal recovery from e-waste. Further chapters cover advancements in hydrogen production, solar cell development, and CO2 conversion, followed by microwave- and radiation-based water treatment and environmental remediation strategies. Together with the first volume, this volume provides an integrated perspective on how electromagnetic-wave technologies can accelerate progress toward a sustainable and circular society.