The global mining industry is essential for resource supply but faces significant environmental hurdles, especially in managing wastewater. Moreover, the industry’s reliance on fossil fuels worsens environmental issues due to greenhouse gas emissions. Pressure retarded osmosis technology (PRO) offers promise in addressing these challenges by utilizing salinity gradients for wastewater treatment and renewable energy generation. While existing research focuses mainly on PRO’s application in wastewater treatment, its integration into mining remains largely unexplored. This study aims to investigate the potential of PRO for treating mine water and generating energy, with a focus on pretreatment methods’ impact on system efficiency. Physicochemical analyses of effluents from various processes of a gold mining company revealed prevalent anions and cations. Various pretreatment techniques, including microbubble ozonation, ultrafiltration, and nanofiltration, were evaluated to determine the most effective and cost-efficient method for achieving stable power density. Results showed that mine water holds promise as a PRO feed solution, offering both electricity generation and wastewater treatment benefits. Particularly noteworthy is the higher power density observed in the effluent sample obtained from the explosive leaching process treated with microbubble ozonation, attributed to its elevated salinity and significant osmotic pressure potential. Moreover, combining microbubble ozonation with nanofiltration proved highly effective in reducing fouling, leading to increased water recovery rates and satisfactory permeate flux levels. This resulted in a notable power density of up to 18 W/m2, comparable to other commonly used feed solutions in PRO applications.