Turning Olive Oil Waste Into Farming Water

New purification method relies on portable equipment that can be loaded onto a truck and moved from one olive oil press to another.

Yaron Kaminsky

The production of olive oil involves the creation of serious environment hazards due to the difficulty in treating the effluents from the manufacturing process. In many instances the runoff simply flows into streams, ultimately polluting the underground water table. Such pollution in the Western Galilee so heavily damaged the Ziv and Kabri natural springs that they were not usable as water sources for 10 months. A new purification method has been developed, however, that treats the olive press runoff and converts it into water which is sufficiently purified that it can be used to irrigate crops.

The system, called Misstow and developed by the Galilee Research Institute in Kiryat Shmona, relies on portable equipment that can be loaded onto a truck and moved from one olive oil press to another. The method initially involves adding substances that help separate the water from the other components in the runoff, causing some of the solid material to settle. The liquid is further purified in tanks. Finally, the effluent undergoes an aeration process in tanks that are heated and drained, producing water of relatively high quality. Researchers are growing small olive trees using the water produced by the process along with smaller amounts of water from Dan River springs.

Development of the method began about three years ago in cooperation with researchers from Greece and Spain and with a 1.6 million-euro ($2.2 million) grant from the European Commission. The research was led by Giora Rytwo and Iggy Litaor of the Galilee Research Institute.

Greek, Spanish partners

According to the institute’s Prof. Uri Marchaim, the method that has been developed makes it possible to dispose of the effluent in a controlled manner and to monitor the amount of water used by the olive presses, then compare it to the amount of effluent they produce. After the project was evaluated for its economic feasibility, it was found that a mobile unit that could treat effluent from 25 to 50 olive presses — and wineries — within a 20 to 30 kilometer radius, would be much more economically efficient.

“The mobile regional equipment also has several advantages, such as providing more consistent waste composition entering the system, and it can be run for almost the entire year rather than just for a short seasonal period,” he said. “Using large quantities, it is also possible to produce electricity with the biogas created by the process that will be sufficient to run the institute. And the heat produced in the process will be used to treat the sludge.”

The project will be presented next week at an international conference in the Upper Galilee being convened by the institute along with the Upper Galilee Regional Council and the Israeli Union for Environmental Defense, also known by its Hebrew name, Adam Teva V’Din. The conference will focus on ways of treating organic waste in the agricultural and tourist sectors.

The institute’s Prof. Dan Levanon, who was previously the chief scientist at the Agriculture Ministry, said the regions cooperating in the oil press project, including the European partners, all face a problem involving the disposal of organic waste, but each region will be required to tailor its approach to prevailing local needs.

Oil and wine

The problem produced by effluent from wineries is similar to that prevailing at olive oil presses, although it is less serious. The problem at oil presses in the north of Israel is considered particularly serious in the region around Lake Kinneret. Several years ago, inspectors from the water authority they were forced to order an olive oil plant in the Hula Valley, whose effluent was polluting the environment, to shut down for violating the stricter pollution standards that apply in areas that drain into the Kinneret.

In recent years, demand for olive oil has been on the increase and new olive groves and oil presses have been developed. Even when effluent from the oil presses is directed into the sewage system, the runoff damages sewage treatment facilities, sometimes even shutting them down altogether. Several years ago a sewage treatment plant near the northern town of Carmiel had to be shut down due to such damage and the polluted water then ran into nearby streams. Even the purified water from treatment plants receiving the olive oil effluent is of lower quality and cannot be used for irrigation.

In recent years, other methods have also be tried to deal with the runoff, including evaporation ponds, efforts to spread the effluent in fields and orchards and controlling its flow to sewage treatment plants. According to Marchaim, however, these other approaches don’t work well enough because the runoff still pollutes the ground and ultimately seeps into springs and streams. The problem, he said, also exists in China, South America and the Mediterranean basin.