Acid insoluble lignin material production by chemical activation of olive endocarps for an efficient furfural adsorption-removal from aqueous solutions.

The present work describes a protocol of chemical activation, with acid catalyst, of olive endocarps to obtain acid insoluble lignin-rich materials with high capacities for the adsorption of furfural present in aqueous media. During biomass activation, factors such as acid concentration, reaction time and temperature, solid/liquid ratio and the presence of water extractives strongly affected both the surface characteristics of the treated bioadsorbents and their capacities for furfural retention (percentage increase close to 600% with respect to the crude biomass). Once a treated solid with good adsorbent properties was obtained, the optimal conditions for adsorption were found: stirring speed 80 rpm, temperature 303 K and adsorbent load 7.5 g solid/50 cm3. Kinetic study indicated the pseudo-second order model provided the best fit of the experimental data. At 303 K, the equilibrium adsorption capacities values ranged from 2.27 mg g-1 to 29.29 mg g-1, for initial furfural concentrations between 0.49 g dm-3 and 12.88 g dm-3. Freundlich model presented the best isotherm (R2 = 0.996 and SE = 4.7%) providing KF and n values of 0.115 (mg g-1) (mg dm-3)-n and 0.610, respectively. Since physical interactions predominate in the adsorption of furfural on chemically activated olive endocarps, the furfural removal process could have occurred reversibly on the heterogeneous surface of the bioadsorbents.

Bioconversion study for xylitol and ethanol production by Debaryomyces hansenii: aeration, medium and substrate composition influence.

Debaryomyces hansenii has been employed to study, initially, the influence of the oxygen availability on D-xylose to xylitol fermentation, as this parameter is considered as one of the most critical variables for this bio alcohol accumulation. Apart from the air supplied in the fermentation process through the stirring vortex (0.0 v/v/min), additional aeration rates (0.1-2.0 v/v/min) effects were discussed. Furthermore, a change in the fermentative medium composition as well as a comparative analysis of D. hansenii behavior with respect to fermentation of D-glucose and D-xylose mixtures solutions, with the aim of producing both xylitol and ethanol bioproducts, were performed. For these purposes, specific growth rates, biomass productivities, specific substrate-uptake rates, overall biomass yields, specific xylitol formation rates and overall xylitol yields values have been calculated, applying a differential method to the kinetic data. Aeration influence was clearly evinced since a faster D-xylose metabolism, for aeration values close to 1.0 v/v/min, was noted. This yeast exhibited a sequential substrate consumption, firstly D-glucose and then D-xylose. The maximum xylitol yield (0.32 kg kg- 1) was obtained for 0.5 v/v/min airflow, remarking a significant reduction of this parameter for both above and below the quoted air supply value.

Valorization of crude olive stone in the removing of polyphenols from crude olive mill wastewater: kinetic, isotherm and mechanism study.

Removal of polyphenols from crude olive mill wastewaters (COMWW) is vital to the development of olive industries. In addition, the exploitation of the residue of the olive oil industry such as crude olive stone (COS) constitutes a valorization of this substance and makes a contribution to the fight against environmental pollution. For this purpose, this study concerns the utilization of COS as an adsorbent of polyphenols from COMWW. The characterization of COS was realized by FTIR, XRD, SEM, PZN, BET and TGA-DTA. The adsorption kinetics and isotherms of polyphenols was analyzed by pseudo-first-order (PFO), pseudo-second-order (PSO), intraparticle diffusion models (MW) and nonlinear models of isotherms Langmuir (LM) and Freundlich (FM) respectively. This study goal at understanding the adsorption mechanism of polyphenols on COS by FTIR and XRD study. The results of adsorption kinetics demonstred that the adsorption capacity of polyphenols 'PP' onto COS is decreased from 381 mg g-1 to 235 mg g-1, with the increasing of the temperature, from 25 °C to 45 °C, indicating an exothermic process, which is confirmed by the negative values of enthalpy ΔH°. Moreover, the negative values of free energy ΔG° and entropy ΔS° indicate the spontaneous and ordered adsorption phenomenon. Kinetic and isotherms studies showed that polyphenols adsorption onto crude olive stone followed PSO kinetic, the FM and LM models were the best fitted. Consequently, this study indicates that crude olive stone could be used as a cheap adsorbent for removing of polyphenols from crude COMWW.

Integrated process for olive oil mill wastewater treatment and its revalorization through the generation of high added value algal biomass.

The two-phase continuous centrifugation process for olive oil extraction generates high amounts of olive oil mill wastewater (OMW), characterized by containing large concentrations of numerous contaminant compounds for the environment. An integral process based on physico-chemical (flocculation, photolysis and microfiltration) and microalgal growth stages was proposed for its treatment. Chemical oxygen demand (COD) removal percentages were 57.5%, 88.8% and 20.5% for flocculation, photolysis and microfiltration, respectively. The global removal percentages of organic load in the primary treatment were 96.2% for COD, 80.3% for total organic carbon (TOC) and 96.6% for total phenolic compounds (TPCs). In secondary treatment, different experiments using the microalgae Chlorella pyrenoidosa were performed on a laboratory scale in stirred batch tank reactors. The OMW concentrations in each culture medium were: 5%, 10%, 25%, 50%, 75% and 100% (v/v). The common experimental conditions were: pH = 7, temperature = 25 °C, agitation speed = 200 rpm, aeration rate = 0.5 (v/v) and illumination intensity = 359 µE m-2 s-1. The highest maximum specific growth rate (0.07 h-1) and volumetric biomass production (1.25 mg/(L h)) values were achieved in the culture with 50% of OMW (v/v). The final biomass obtained had a high percentage of carbohydrates, whose content ranged from 30.3% to 89.2% and the highest lipid content (34.2%) was determined in the culture with 25% of OMW (v/v). The final treated water is suitable for its use in irrigation, discharge to receiving waters or for being reused in the same process.

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% COD(removal), 19.2% total phenols(removal), and 28.1% total suspended solids(removal) were registered at the end of the UV/TiO2 process for OMW, whereas 58.3% COD(removal), 27.5% total phenols(removal), and 25.0% total suspended solids(removal) 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 COD(removal), in contrast with 33.2% of COD(removal) 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.

Changes of the wax contents in mixtures of olive oils as determined by gas chromatography with a flame ionization detector.

Mixing of refined olive-pomace oil with virgin olive oil is a fraud that has been tried often. Normally, the tests that detected the fraud were determinations of wax esters, erythrodiol+uvaol, and stigmastadienes contents. The most common is the determination of wax esters content (extra virgin olive oil is very poor in wax esters, usually less than 100 mg/kg). In this work, the variations of individual wax esters (C40, C42, C44, and C46), with different degrees of unsaturation content, and total wax esters were studied when extra virgin olive oil and refined pomace-olive oil were mixed. The following mixtures were prepared: extra virgin olive oil plus 1, 2, 4, 6, 8, 10, 12, 15, 18, 25, 35, 45, 50, and 80% of refined olive-pomace oil. In all cases, individual and total wax ester content variation was linear with increasing percentage of refined olive-pomace oil in the mixture. The variation of the total wax esters content can be adjusted according to the equation: Total wax esters, mg/kg = 14.3 x (% refined olive-pomace oil) + 83.9.

Changes in phenolic compounds and Rancimat stability of olive oils from varieties of olives at different stages of ripeness.

BACKGROUND: Recently, diets rich in natural foods and food-derived components, such as phenolic compounds, have received a great deal of attention because they are perceived as 'safe' and 'non-medicinal'. In fact, some are known to function as chemopreventive agents against oxidative damage, cerebrovascular disease, and aging. RESULTS: Phenolic compounds, natural antioxidants present in virgin olive oil, play an important role in oil quality by contributing significantly to protecting oil stability against oxidation. In addition, polyphenols are the main contributors to olive oil bitterness, astringency and pungency. The data were fit by linear regression, giving Rancimat stability (h) = 0.18× Total polyphenols (mg L(-1)) in the virgin olive oil. CONCLUSIONS: The practice of harvesting ripe olives as soon as possible to produce oils of high phenolic contents and thus high oxidative stability implies bitter and piquant oils, this being admissible for oils of some varieties but detrimental to others appreciated in the market for being more fruity and sweeter.

Elimination of pesticide residues from virgin olive oil by ultraviolet light: preliminary results.

Virgin olive oil is one of the essential products for the economy of Mediterranean countries. The possible residues of pesticides that can reach the oil may be a risk to public health, thus causing the prohibition of its marketing by the health authorities. This paper is a preliminary study on photochemical degradation of pesticide residues using a small-scale prototype (1L capacity). The method presents an effective alternative for the complete photodegradation or reduction of these chemicals using ultraviolet light without harming the quality parameters of the virgin olive oil. The photodegradation yields have varied within the range 7-80% depending on the time and temperature applied.

Use of industrial wastewater from olive-oil extraction for biomass production of Scenedesmus obliquus.

The use of rinse water (RW) from two-phase centrifugation in the olive-oil extraction industry has been studied in relation to the production of the microalga Scenedesmus obliquus (CCAP 276/3A). The characterization of the wastewater indicates that it is N deficient. The highest value of maximum specific growth rate, 0.044 h(-1) was registered in the culture with 5% RW. However, biomass productivity proved greater in the culture with 100% RW. The specific growth rates were adjusted to a model of inhibition by substrate. The content in normalized chlorophyll diminished with the duration of the cultures, reaching a minimum CHL'(min) value, which showed an inhibition type similar to that of the specific growth rate. The yield in protein indicates that the cultures were limited by N to approximately 50% RW. The greater specific rate of protein synthesis during the exponential phase was 3.7 mg/gh to 50% RW. It was found that the composition of the lipid fraction of the biomass depended on the percentage of wastewater used as the nutrient medium, reaching the highest percentages of monounsaturated, polyunsaturated, and essential fatty acids in the culture with 100% RW.