Swine wastewater contains nutrient materials such as Ammonium (NH4+), Phosphate (PO43-), Total Kjeldahl Nitrogen (TKN), and Total Phosphorus (TP) which can result in eutrophication and disrupt the surrounding environment. So, this study aims to develop a nutrient-adsorbing material from spent coffee grounds for the treatment of swine wastewater. The adsorbent was produced through anaerobic pyrolysis of coffee grounds impregnated with various concentrations of MgCl2 under different pyrolysis durations (30, 60, 90, 120, 150, and 180 minutes) and temperatures (500°C, 550°C, 600°C, 650°C, and 700°C). Subsequent experiments were carried out to determine the optimal conditions for the adsorbent in treating swine wastewater. The preliminary results were then used to test real-world scenarios using coffee-ground biochar in wastewater treatment. The results indicated that the M 2/650/30 sample—prepared with 2% MgCl2, pyrolyzed at 650°C for 30 minutes—was the most effective adsorbent. In real-scenario testing, this sample achieved an ammonium removal efficiency of 66.53% and a phosphate removal efficiency of 88.82%. Moreover, the adsorbent was also capable of adsorbing other nitrogen and phosphorus forms, as evidenced by its higher adsorption capacities for TKN and TP compared to NH4⁺ and PO43⁻. The material modifications significantly enhanced nutrient recovery from wastewater, such as ammonium and phosphate, while simultaneously reducing the environmental emissions associated with coffee waste. This study demonstrates the potential of spent coffee grounds as an effective adsorbent for treating swine wastewater. The findings may have important implications for the management of livestock agricultural waste, which remains an urgent environmental issue.