**3.1.1 Deacidification**

Conventional chemical and physical deacidification methods have some drawbacks such as use of large amount of water and chemicals, and loss of neutral oil (Kale et al., 1999). Membrane technology may be proposed as a new alternative deacidification process for edible oils (Bhosle & Subramanian, 2005).

A membrane-based process for deacidification of lampante olive oil was undertaken by Hafidi et al. ( 2005a). Their objective was to deacidify, while also preserving the sensitive and bioactive components in the oil by operating at ambient temperature. The results showed that oils were obtained almost FFA- and soap-free in a single step. In another study, the impact of this process on some minor components and on the organoleptic characteristics of the purified olive oils was investigated (Hafidi et al., 2005b). It was reported that, while a complete deacidification was achieved, some desirable components, mainly phenolics, were eliminated during the filtering process. Thus, it was suggested to focus on reducing the elimination of phenolic compounds and the improvement of the organoleptic characteristics of the filtered oils.

### **3.1.2 Wastewater treatment**

Olive mill wastewater (OMW), a by-product of olive oil extraction, is one of the most contaminated effluents. The polluting load is due to organic substances such as sugars, tannins, polyphenols, polyalcohols, pectins, lipids, proteins and organic acids, (Cassano et al., 2011). Phenolic compounds can act as phytotoxic components, inhibiting microbial growth as well as plant germination and vegetative growth (Morillo et al., 2009).

Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) of OMW may be as high as 100 and 200 g L-1, respectively (de Morais Coutinho et al., 2009). Besides, OMWs are considered as a potential source for the recovery of antioxidant, antiatherogenic and anti-inflammatory biophenols (Obied et al., 2005). Detoxification and recovery of valuable components from wastewater are among the most useful treatments based on membrane technology.

In the study of Paraskeva et al. (2007), combinations of different membrane processes were used for the fractionation of OMW. Ultrafiltration in combination with nanofiltration and/or reverse osmosis were found to be very efficient for this process. It was shown that better efficiency of the OMW treatment was achieved by applying reverse osmosis after ultrafiltration. The ultrafiltration concentrate was found to contain the largest portion of fats, lipids, solids, etc. Further processing with nanofiltrationmay be employed for the separation of a greater part of phenols.

Membrane technology has been used in the edible oil industry for degumming, deacidification, waste water treatment, recovery of solvent from micelles, condensate return, catalyst recovery and hydrolysis or synthesis of structured lipids with two-phase membrane reactors, involving pigment removal, separation and concentration of minor compounds in the oil. Despite its use in other sectors of the edible oil industry, this technology has not been

Conventional chemical and physical deacidification methods have some drawbacks such as use of large amount of water and chemicals, and loss of neutral oil (Kale et al., 1999). Membrane technology may be proposed as a new alternative deacidification process for

A membrane-based process for deacidification of lampante olive oil was undertaken by Hafidi et al. ( 2005a). Their objective was to deacidify, while also preserving the sensitive and bioactive components in the oil by operating at ambient temperature. The results showed that oils were obtained almost FFA- and soap-free in a single step. In another study, the impact of this process on some minor components and on the organoleptic characteristics of the purified olive oils was investigated (Hafidi et al., 2005b). It was reported that, while a complete deacidification was achieved, some desirable components, mainly phenolics, were eliminated during the filtering process. Thus, it was suggested to focus on reducing the elimination of phenolic compounds and the improvement of the

Olive mill wastewater (OMW), a by-product of olive oil extraction, is one of the most contaminated effluents. The polluting load is due to organic substances such as sugars, tannins, polyphenols, polyalcohols, pectins, lipids, proteins and organic acids, (Cassano et al., 2011). Phenolic compounds can act as phytotoxic components, inhibiting microbial

Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) of OMW may be as high as 100 and 200 g L-1, respectively (de Morais Coutinho et al., 2009). Besides, OMWs are considered as a potential source for the recovery of antioxidant, antiatherogenic and anti-inflammatory biophenols (Obied et al., 2005). Detoxification and recovery of valuable components from wastewater are among the most useful treatments based on membrane

In the study of Paraskeva et al. (2007), combinations of different membrane processes were used for the fractionation of OMW. Ultrafiltration in combination with nanofiltration and/or reverse osmosis were found to be very efficient for this process. It was shown that better efficiency of the OMW treatment was achieved by applying reverse osmosis after ultrafiltration. The ultrafiltration concentrate was found to contain the largest portion of fats, lipids, solids, etc. Further processing with nanofiltrationmay be employed for the

growth as well as plant germination and vegetative growth (Morillo et al., 2009).

**3.1 Applications of membrane technology in the olive oil industry** 

broadly extended to olive oil processing.

edible oils (Bhosle & Subramanian, 2005).

organoleptic characteristics of the filtered oils.

**3.1.2 Wastewater treatment** 

separation of a greater part of phenols.

technology.

**3.1.1 Deacidification** 

In another study, OMW was used to investigate the variation of COD and total organic carbon (TOC) removal efficiencies together with permeate fluxes for ultrafiltration process (Akdemir & Ozer, 2009). Two types of ultrafiltration membranes which are JW (polyvinylidinedifluoride) and MW (ultrafilic) gave close removal efficiencies. Ultrafiltration membranes with bigger molecular weight cut-offs for OMW were suggested to increase flux value and decrease efficiency loss. In their previous work, observed COD removal efciency by ultraltration without pretreatment was found higher than 80% by promising value for OMW (Akdemir & Ozer, 2008). El-Abbassi et al. (2009) studied the treatment of OMW to obtain high value-added compounds such as sugar and polyphenols, by membrane distillation. Two types of commercial membranes, polytetrafluoroethylene (TF200) and polyvinilydene fluoride (GVHP), were compared and the effects of membrane parameters on direct contact membrane distillation (DCMD) performance (i.e. permeate flux and polyphenols retention) were investigated. Their results demonstrated that TF200 had a better separation coefficient (99%) after 9 h of DCMD operation than that of GVHP (89%). OMW concentration factor was found to be 1.72 for TF200, whereas it was only 1.4 for GVHP after 9 h.

Another OWM treatment was tested by Dhaouadi and Marrot (2008). Diluted solutions of OMW were treated in a ceramic membrane bioreactor with biomass specially acclimated to phenol. It gave stabilized permeate flux with zero suspended solid and no phenolic compounds. No fouling problems occurred during the experiments. OMW treatment in a membrane bioreactor can be used as a pre-treatment stage for the removal of phenolic compounds before a conventional biological process.

Recently, Coskun et al. (2010) studied the treatment of OWM using nanofiltration and reverse osmosis membranes. They reported that overall COD removal efficiencies were 97.5%. It was shown that reverse osmosis membranes are capable of producing a higher quality effluent from OMW than nanofiltration membranes. NF270 membranes were found to be most applicable among nanofiltration membranes due to their higher fluxes and higher removal efficiencies. In addition, it was found that centrifugation alone can be used as a promising option for primary treatment of OMWs with nanofiltration process.

In summary, there appears to be a potential for the use of membrane technology in the olive oil industry. Membranes can provide an opportunity to develop alternative environmentally friendly processes for the refining of olive oils and treatment of OWM. Despite promising results, further studies must be done on this new approach, namely, to evaluate the effect of the process on the oil composition, to improve flow rate, to reduce fouling inclusions and to assess economic viability.
