Zero Liquid Discharge (ZLD) and Minimal Liquid Discharge (MLD) desalination systems powered by Renewable Energy Sources (RES) offer sustainable solutions for brine treatment and valorization. Brine, a highly concentrated saline solution resulting from industrial processes and desalination, poses challenges due to its high salinity and potential harm to ecosystems. This chapter delves into the fundamental aspects of ZLD and MLD, highlighting their significance in addressing the brine disposal issue. ZLD aims to eliminate liquid discharge by recovering and reusing all water from the brine stream, while MLD focuses on minimizing liquid discharge while maximizing water recovery. Various technologies and processes, including membrane separation, thermal evaporation, and crystallization, are employed in brine treatment using ZLD/MLD systems. The chapter also emphasizes the integration of RES in ZLD/MLD systems, showcasing their potential for sustainable operation. It presents case studies of successful implementations where RES such as solar and wind power have been utilized to power ZLD/MLD systems. These examples demonstrate the feasibility and benefits of utilizing RES, including reduced carbon emissions and enhanced energy efficiency. By exploring the concepts of ZLD and MLD, brine treatment methodologies, and real-world examples of RES-powered ZLD/MLD systems, this chapter provides important insights for researchers, engineers, and policymakers working towards sustainable brine management and resource recovery. The integration of RES in ZLD/MLD systems represents a promising pathway for achieving environmentally friendly and economically viable solutions to brine treatment and valorization.