<p>This study employs a life cycle assessment (LCA) methodology to evaluate the environmental impact of a paper mill wastewater treatment plant. Our investigation extends to comparing the eco-efficiency of utilizing biogas versus flaring it during wastewater treatment from Upflow Anaerobic Sludge Blanket (UASB) and explores the reuse of treated water within the production system. The ReCiPe (H) v1.13 method was applied to assess impact categories such as Climate Change, Ozone Depletion and Human Toxicity. The results showed a substantial reduction in environmental indicators by reusing biogas and treated water, highlighting the potential for sustainable practices in the paper industry. Transitioning from traditional methods to advanced technologies significantly lowers pollution indicators, aligning with global sustainability goals. Moreover, CO₂ emissions decrease fourfold when adopting innovative treatment technologies. These findings underscore the economic and environmental benefits of embracing advanced wastewater treatment, providing valuable insights for sustainable water management practices in the paper industry.</p>