Optimized Zeolite Adsorption for Reducing Organic Load in Olive Mill Wastewater: Kinetics & Isotherm Analyses

Olive mill wastewater (OMW) is a major contaminant in olive-growing regions due to its high organic and solid content. Although rich in nutrients, OMW also contains significant levels of antibacterial and phytotoxic phenolic compounds that hinder biodegradation. In this study, fresh OMW from olive mills in northern Jordan was treated with zeolite to reduce its organic matter, monitored through chemical oxygen demand (COD) measurements. The effects of temperature, pH, and zeolite concentration on COD removal were analyzed, revealing that higher temperatures (25°C to 45°C) reduced adsorption efficiency, while optimal removal occurred at pH 4. Increasing zeolite concentration from 1 g L-1 to 2 g L-1 improved removal rates. Adsorption kinetics followed a pseudo-second-order model with a rate constant (k2) of 0.62 g. mg-1 s⁻¹. The Freundlich isotherm provided the best fit for the adsorption data, with constants KF and n determined as 1.33 and 1.22, respectively, outperforming the Langmuir model.