Reducing the environmental impact of olive mill wastewater in Jordan, Palestine and Israel

Olive mill wastewater (OMW) generated by the olive oil extraction process is the main waste product of this industry. Approximately 5.4 x 10(6) m(3) of olive mill wastewater are produced annually worldwide. The majority of it is being produced in the Mediterranean Basin. The uncontrolled disposal of OMW is becoming a serious environmental problem, due to its high organic COD concentration, and because of its high content of microbial growth-inhibiting compounds, such as phenolic compounds and tannins. The improper disposal of OMW to the environment or to domestic wastewater treatment plants is prohibited due to its toxicity to microorganisms, and because of its potential threat to surface and groundwater, due to the current lack of appropriate alternative technologies to properly treat OMW. In the Mediterranean area it is most often discharged directly into sewer systems and water streams or concentrated in cesspools, despite the fact that such disposal methods are prohibited in many Mediterranean countries. The Research and Development Center of the Galilee Society (GS) in Israel is coordinating a joint USAID funded project with partners from Hebron University, Palestine, The Royal Scientific Society (RSS) in Jordan, and the Technion - Haifa, Israel. The project aims to investigate industrially feasible physico-chemical and biological treatment systems in order to reduce the environmental impact of OMW. During the last three years, the partners conducted an inclusive survey on location, type of olive mills, production capacity, OMW generation, current practiced methods for the disposal of OMW and data related to the socio-economic situation of the farmers in the region. Furthermore, laboratory and pilot-scale experiments have been conducted in the GS, RSS and the Technion to examine the most effective physico-chemical and biological treatment systems to treat OMW. The experimental work was conducted to identify the most efficient anaerobic treatment for OMW. It was demonstrated that in the up-flow anaerobic sludge blanket reactor (UASB) reactor, COD removal efficiency Of 75-85 per cent was reached at a Hydraulic Retention Time (HRT) of 5 days with an influent COD concentration of about 40 gL(-1) and Organic Loading Rate (OLR) = 7-8 g CODL-1.d(-1). Based on the results obtained in bench scale experiments, a demonstration pilot scale system was designed and constructed in Hebron district to continuously treat OMW.