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Content archived on 2024-05-21

Development of a new mobile waste water treatment process for sme olive mills


Scientific objectives and approach:

The R&D programme for MOWOM project has got 8 Work Packages (A - H) each resulting in key deliverables:
The "Determination of functional requirements" workpackage (A) provides the users' demands and requirements. In the workpackage B ("Laboratory testing") a characterisation of the wastewaters is performed, and the best methods for its treatment are determined. Based on the information acquired in workpackages A and B, the "Technical specifications" workpackage (C) will allow to determine how will the technical objectives be reached. The "Development of the pilot plant" workpackage (D) will include its design and construction, based on the specifications determined in workpackage C. In the "Testing of the pilot plant" workpackage (E) the prototype will installed and operated in the user SMEs' production lines, trying to optimise it according to the established technical requirements. In parallel to workpackage E, an analysis of the obtained residue will be performed in order to find out the best ways of disposal or reutilisation. Finally, two more Workpackages will deal with the "Exploitation and Dissemination" (G) activities and with the "Management" of the entire project (H).

Problems to be solved:

Olive oil production is an important agro-alimentary branch in Europe. About 9.7 million tons of olives are grown annually from which approximately 1.9 million tons of olive oil are processed in several thousands of olive oil mills (FAOSTAT database). Especially in Portugal, Italy and Greece, the majority of olive mills are small enterprises, family-owned in many cases, and employ less than 10 workers. For example, the production of olive oil in Portugal is characterised by the existence of about 1400 olive mills and more than 90% of these represent less than 50% of the production.
Currently, there are three systems used for the extraction of olive oil: traditional, 3-phases and 2-phases. While the two-phases system results in a paste-like residue, both the traditional and the three phases system produce a liquid wastewater (olive mill wastewaters, OMW). The 3-phases system results in the production of approximately 1.2 kg liquid and 0.5 kg solid waste per 1 kg olives (Padilla, 1998), while the traditional pressing process produces 0.5 kg solid waste and 0.5 wastewater. According to the Confederation of the European Olive Oil Industry (FEDOLIVE), about 12,000 oil mills currently produce over 1.9 million tons of olive oil in the EU. More than half of them are estimated to be still working with the traditional or the 3-phases system (especially small mills), which result in a wastewater production of about 3.4 million tons annually.
This residue (OMW) contains high levels of phenols and polyphenols (which are phytotoxic, and inhibit bacteria development), together with high organic matter content and high COD, and also releases a strong disagreeable odour. It is estimated that in the milling of 1000 kg of olives, the resulting wastewater is as polluting as a village with a population of 300-500 people. Due to this, national legislations in European olive oil-producing countries already forbid the direct disposal of OMW in rivers.
The disposal strategy for this liquid residue today comprises mainly evaporation or depositing in olive plantations, especially in the case of small olive mills (frequently family-owned) which cannot afford anaerobic stationary plants. However, for environmental reasons these methods are no longer acceptable, as they lead to foul odours and groundwater pollution, and new EU regulations are very likely to forbid it.
The project proposed here offers the opportunity to solve this waste disposal environmental problem in the particular case of small olive mills by developing a mobile and flexible wastewater treatment plant (MOWOM). The development of the MOWOM system has the potential to provide substantial savings in capital costs in comparison to stationary treatment plants since it can be transported from one olive mill to another in order to treat the wastewater.

Expected Impacts:

The proposed MOWOM system units will allow small olive mills to treat their stored OMW by mechanical/chemical means reaching an elimination of 95% of its organic matter content, whit simultaneous removal of toxic phenols and polyphenolic compounds, and at an affordable cost. This will contribute to a better air and groundwater quality. From the economical point of view, the MOWOM system will lead to reduction of wastewater treatment costs at least by 30 % in comparison to state of the art anaerobic treatment plants when new regulations come into force, and will create employment for its construction, operation and maintenance.

Call for proposal

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EU contribution
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Centro Empresarial Sintra-Estoril V. E29, Capa Rot
2710-090 SINTRA

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Total cost
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Participants (11)