Final purification of synthetic olive oil mill wastewater treated by chemical oxidation using ion exchange: Study of operating parameters

In this research work, ion exchange (IE) is presented as a suitable option for purification of olive oil mill wastewater (OMW) previously treated by means of a secondary treatment (OMWST). This pretreatment consisted in Fenton-like oxidation process, followed by coagulation–flocculation and filtration through olive stones. The parametric requirements for drinking water production or at least for public waterways discharge were achieved using a combination of two IE columns working in series at bench scale. The IE resins used in this study were Dowex Marathon C and Amberlite IRA-67. The effect of contact time, operating temperature and flow rate on simultaneous removal of sodium, total iron, chloride and phenols (the major pollutant species in OMWST) were investigated. Removal percentages of sodium, chloride and total iron increased with incrementing the contact time. Equilibrium was obtained in about 30 min for all ions and ion concentrations values determined were lower than the maximum levels for drinking water standards. On the other hand, adsorption efficiencies of sodium, total iron and chloride ions were found to be not considerably affected by the operating temperature. The highest phenols removal percentage (around 100%) was obtained in the first minutes for 298 K and 10 L/h.