Olive mills wastewater treatment using local natural Jordanian clay

In the Mediterranean area, olives are harvested and sent to mills where olive oil is extracted. These mills produce two types of wastes, namely olive kernel and olive mills wastewater (OMW). This OMW is considered an environmental problem because of its high organic content (COD over 80–200 g/l), high phenolics content (more than 400 mg/l), and low acidic pH (3–6). This study is about investigating the feasibility of using simple naturally occurring local Jordanian clay as a possible adsorbent to decrease the levels of the above negative characteristics of raw OMW as a step in developing a methodology to solve OMW problem without creating new problems to freshwater supply resources. Natural clay was calcined at several temperatures (350–550°C), some of which were further subjected to acid treatment using 1, 3, and 5 M-HCl solutions at 85°C. These treated clays were contacted with OMW in batch experiments to decide on optimum conditions to be used for a continuous packed bed treatment system. COD and phenolics contents of raw OMW were both reduced by about 10–20%. Packed bed of treated clay reduced COD of raw OMW by 50%. These results are promising and warrant further investigation.