Olive mills wastewater treatment using mixed adsorbents of volcanic tuff, natural clay and charcoal

Olive mills wastewater (OMW) is considered an environmental hazard because of its high organic content (COD over 80-200 g/L), high phenols (more than 400 mg/L) and acidic pH (3 to 6). This study investigated employing simple natural locally available materials as adsorbents to decrease the levels of the above negative characteristics of OMW. Specifically, volcanic tuff (VT), natural clay and charcoal were investigated as possible adsorbents of OMW's organic matter. The above possible adsorbents were treated employing different physical, thermal and/or chemical methods, and characterized using XRD, SEM, EDX and BET surface area analyses, and then utilized in adsorption experiments as single or mixed adsorbents. Synergistic effects on COD and phenols uptake were noticed when both treated clay and treated VT in addition to charcoal were employed in combinations. Reductions in COD and phenols concentrations reached 14% and 21% respectively. Based on the results of this work, the investigated VT along with its treatment protocols would not be recommended to be employed as a possible practical adsorbent in the treatment of OMW.