Removal of phenolic compounds from olive mill wastewater (OMW) by tailoring the surface of activated carbon under acidic and basic conditions.

Olive mill wastewater (OMW), a by-product of olive oil production, poses significant environmental risks due to its acidity and high polyphenol content, particularly in water-scarce regions like Jordan. This study developed a cost-effective approach to reduce the phenolic content in OMW using modified granular-activated carbon (GAC). Commercial GAC, chosen for its high surface area and adsorption capacity, was modified via oxidative treatment with concentrated nitric acid and reductive treatment using 10 wt.% ammonia solution. The modified GAC samples were tested for phenolic compound (PC) adsorption from OMW under varying surfactant types, concentrations, and pH levels using a batch method. The optimized conditions revealed that reduced GAC at pH 9 achieved the highest removal efficiency, reducing the phenolic content by 88% after 48 h. Surfactants had no significant effect on the performance of reduced GAC. Desorption tests after 7 and 32 days indicated a minimal release of PCs, confirming strong binding to the GAC surface. These findings demonstrate the potential of reduced GAC as a sustainable and cost-efficient solution for treating OMW, addressing the critical challenges in water resource management and environmental pollution in regions like Jordan.