Adsorption is emerging as an innovative and promising method for treating wastewater from tanneries in Morocco. This sector is crucial to the local economy yet contributes significantly to environmental pollution. The tanning process produces effluents rich in organic and inorganic contaminants, including heavy metals, dyes, and toxic chemicals. Consequently, there is an urgent need to develop sustainable solutions for managing these wastewater streams to safeguard environmental and water resource integrity. This chapter investigates the utilization of calcium carbonate-based materials as adsorbents for treating tannery effluents. Given their availability and relatively low cost, these materials present a viable alternative to more expensive and energy-intensive treatment technologies. Adsorption, as a physical process, facilitates the attachment of pollutants to the surface of adsorbents, thereby enhancing their removal from wastewater. Experimental studies were conducted to evaluate the adsorption efficiency of various forms of calcium carbonate, including calcite and aragonite. The findings indicate a significant adsorption capacity, evidenced by marked reductions in the concentrations of heavy metals and organic contaminants in the treated effluents. Furthermore, the research explores the optimal conditions influencing adsorption efficacy, including pH, temperature, contact time, and initial pollutant concentrations. The chapter also elucidates the underlying mechanisms of adsorption, such as electrostatic interactions and chemical bonding, which enhance the effectiveness of the process. Incorporating calcium carbonates into an adsorption framework addresses wastewater treatment and aligns with waste management strategies that convert byproducts from the leather industry into valuable resources. In conclusion, the implications of adopting this innovative approach for the Moroccan leather industry are significant. By implementing adsorption as a wastewater treatment method, tanneries can mitigate their environmental footprint while enhancing compliance with regulatory standards. This strategy fosters a transition toward more sustainable industrial practices, contributing to a circular economy that prioritizes resource optimization and waste reduction. The chapter advocates for continued technological innovation and research in wastewater treatment methodologies, emphasizing the potential of utilizing natural and cost-effective materials as sustainable solutions to the environmental challenges confronting the tanning sector in Morocco.