María Dolores Víctor-Ortega

Effective treatment of olive mill effluents from two-phase and three-phase extraction processes by batch membranes in series operation upon threshold conditions.

Production of olive oil results in the generation of high amounts of heavy polluted effluents characterized by extremely variable contaminants degree, leading to sensible complexity in treatment. In this work, batch membrane processes in series comprising ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) are used to purify the effluents exiting both the two-phase and tree-phase extraction processes to a grade compatible to the discharge in municipal sewer systems in Spain and Italy. However, one main problem in applying this technology to wastewater management issues is given by membrane fouling. In the last years, the threshold flux theory was introduced as a key tool to understand fouling problems, and threshold flux measurement can give valuable information regarding optimal membrane process design and operation. In the present manuscript, mathematical approach of threshold flux conditions for membranes operation is addressed, also implementing proper pretreatment processes such as pH-T flocculation and UV/TiO2 photocatalysis with ferromagnetic-core nanoparticles in order to reduce membranes fouling. Both influence the organic matter content as well as the particle size distribution of the solutes surviving in the wastewater stream, leading, when properly applied, to reduced fouling, higher rejection and recovery values, thus enhancing the economic feasibility of the process.

Reuse of olive mill effluents from two-phase extraction process by integrated advanced oxidation and reverse osmosis treatment

In this work, complete reclamation of the olive mill effluents coming from a two-phase olive oil extraction process (OME-2) was studied on a pilot scale. The developed depuration procedure integrates an advanced oxidation process based on Fentons reagent (secondary treatment) coupled with a final reverse osmosis (RO) stage (purification step). The former aims for the removal of the major concentration of refractory organic pollutants present in OME-2, whereas the latter provides efficient purification of the high salinity. Complete physicochemical composition of OME-2 after the secondary treatment was examined, including the particle size distribution, organic matter gradation and bacterial growth, in order to assess the selection of the membrane and its fouling propensity. Hydrodynamics and selectivity of the membrane were accurately modelized. Upon optimization of the hydrodynamic conditions, the RO membrane showed stable performance and fouling problems were satisfactorily overcome. Steady-state permeate flux equal to 21.1 L h(-1)m(-2) and rejection values up to 99.1% and 98.1% of the organic pollutants and electroconductivity were respectively attained. This ensured parametric values below standard limits for reuse of the regenerated effluent, e.g. in the olives washing machines, offering the possibility of closing the loop and thus rending the production process environmentally friendly.

Physicochemical analysis and adequation of olive oil mill wastewater after advanced oxidation process for reclamation by pressure-driven membrane technology

Physicochemical characterization of olive mill wastewaters (OMW) was studied after a primary and secondary treatment was implemented in an olive oil factory in Jaén (Spain), comprising natural precipitation, Fenton-like reaction, flocculation-sedimentation and olive stone filtration in series. The application of membrane technology in improving the quality of the secondary-treated OMW (OMW/ST) was examined, to reduce the hazardous electroconductivity (EC) values (2-3 mS cm(-1)). Particle size distribution on OMW/ST shows supra-micron colloids and suspended solids as well as sub-micron particles with a mean size below 1.5 μm remaining in considerable concentration. The high organic pollutants percentage (31.7%) registered with an average diameter below 3 kDa is sensibly relevant for membrane fouling. Mesophilic aerobic bacteria growth warns of possible membrane biofouling formation. The saturation index indicates to work upon recovery factor below 90%. Finally, operating at a pressure equal to 15 bar ensured low fouling and high flux production on the selected NF membrane (69.9 L h(-1)m(-2)) and significant rejection efficiencies (55.5% and 88.5% for EC and COD). This permits obtaining an effluent with good quality according to the recommendations of the Food and Agricultural Association (FAO) with the goal of reusing the regenerated water for irrigation.

A Novel Photocatalyst with Ferromagnetic Core Used for the Treatment of Olive Oil Mill Effluents from Two-Phase Production Process

Photocatalytic degradation of olive oil mill wastewater from two-phase continuous centrifugation process was studied. A novel photocatalyst with ferromagnetic properties was characterized and investigated. The degradation capacity of the photocatalytic process of olive oil washing wastewater (OMW) and mixture of olives and olive oil (1 v/v) washing wastewaters (MOMW) was demonstrated. At lab-scale, the %COD removal and residence time (τ) for MOMW and OMW were 58.4% (τ = 2 h) and 21.4% (τ = 3 h), respectively. On the other hand, at pilot scale, 23.4% CODremoval, 19.2% total phenolsremoval, and 28.1% total suspended solidsremoval were registered at the end of the UV/TiO2 process for OMW, whereas 58.3% CODremoval, 27.5% total phenolsremoval, and 25.0% total suspended solidsremoval for MOMW. Also, before the UV/TiO2 reaction, a pH-T flocculation operation as pretreatment was realized. The overall efficiency of the treatment process for MOMW was up to 91% of CODremoval, in contrast with 33.2% of CODremoval for OMW.

Performance Modeling and Cost Analysis of a Pilot-Scale Reverse Osmosis Process for the Final Purification of Olive Mill Wastewater

A secondary treatment for olive mill wastewater coming from factories working with the two-phase olive oil production process (OMW-2) has been set-up on an industrial scale in an olive oil mill in the premises of Jaén (Spain). The secondary treatment comprises Fenton-like oxidation followed by flocculation-sedimentation and filtration through olive stones. In this work, performance modelization and preliminary cost analysis of a final reverse osmosis (RO) process was examined on pilot scale for ulterior purification of OMW-2 with the goal of closing the loop of the industrial production process. Reduction of concentration polarization on the RO membrane equal to 26.3% was provided upon increment of the turbulence over the membrane to values of Reynolds number equal to 2.6 × 104. Medium operating pressure (25 bar) should be chosen to achieve significant steady state permeate flux (21.1 L h−1 m−2) and minimize membrane fouling, ensuring less than 14.7% flux drop and up to 90% feed recovery. Under these conditions, irreversible fouling below 0.08 L h−2 m−2 bar−1 helped increase the longevity of the membrane and reduce the costs of the treatment. For 10 m3 day−1 OMW-2 on average, 47.4 m2 required membrane area and 0.87 € m−3 total costs for the RO process were estimated.

On the effect of ph and operating conditions on nanofiltration of two-phase olive mill wastewater

On the Effect of pH and Operating Conditions on Nanofiltration of Two-Phase Olive Mill Wastewater Javier Miguel Ochando-Pulido, Maria Dolores Víctor-Ortega, Marco Stoller, Antonio Martínez-Férez a Chemical Engineering Department, University of Granada, Avda. Fuentnueva s/n, 18071 Granada, Spain University of Rome “La Sapienza”, Department of Chemical Engineering, Via Eudossiana, 18-00184 Rome, Italy jmochandop@ugr.es

Analysis of the Fouling Build-up of a Spiral Wound Reverse Osmosis Membrane in the Treatment of Two-phase Olive Mill Wastewater

Analysis of the Fouling Build-up of a Spiral Wound Reverse Osmosis Membrane in the Treatment of Two-phase Olive Mill Wastewater Javier Miguel Ochando-Pulido,Marco Stoller,Maria Dolores Víctor-Ortega, Antonio Martínez-Férez a Chemical Engineering Department, University of Granada, Avda. Fuentnueva s/n, 18071 Granada, Spain University of Rome “La Sapienza”, Department of Chemical Engineering, Via Eudossiana, 18-00184 Rome, Italy jmochandop@ugr.es

Comparison of the Performance of Two Reverse Osmosis Membranes for the Final Purification of Olive Mill Wastewater

Two quite different reverse osmosis (RO) polymeric membranes were examined for the final purification of olive mill wastewater from two-phase olive mills (OMW2): the first one is a thin-film composite (TFC) membrane consisting of polyamide active layer on polysulfone ultrafiltration support, whereas the other one is a low-pressure membrane made of asymmetric polyamide. A net operating pressure (PTM) of 25 bar was found as the target for the TFC membrane, whereas for the asymmetric one a PTM of 8 bar was chosen, given that similar flux decay but still significant productivity was observed by increasing the PTM for this membrane. These results are confirmed by the fouling index (b) values calculated for each membrane. Complete removal of suspended solids, phenolic compounds and iron was achieved by both membranes. Otherwise, the asymmetric membrane ensured slightly higher organic matter (COD) and electroconductivity (EC) reduction, leading to a COD concentration in the permeate stream equal to 3.7 mg L-1 and 1.4 mg L-1 (TFC vs. asymmetric), whereas the EC values were 97.0 and 31.0 μs cm-1, respectively. This would permit reusing the purified effluent provided by both membranes in the production process and close the loop at industrial scale. Moreover, the asymmetric membrane provides a steady-state flux value of the same order of that yielded by the TFC membrane upon more than three times less PTM (14.9 L h-1m-2 at PTM = 8 bar vs. 15.2 L h-1m-2 at PTM = 25 bar), implying a reduction of the specific energy consumption above 50 %, from 0.30 € m-3 for the TFC membrane to 0.14€ m-3 for the asymmetric one.