Degradation Of Olive Mill Wastewater Research Articles

Experimental study on the inhibition of glucose and olive mill wastewater degradation by volatile fatty acids in anaerobic digestion

Experimental study on the inhibition of glucose and olive mill wastewater degradation by volatile fatty acids in anaerobic digestion

Olive Mill Wastewater (OMW) Treatment Using Photocatalyst Media

A new nanophotocatalysts series of M2Zr2O7 (M = Mn, Cu, and Fe) and doped Fe2Zr2O7 systems were prepared via sol-gel using the pechini method, characterized, and tested in photocatalytic degradation of olive mill wastewater (OMW). The photocatalytic degradation of the prepared materials was evaluated by measuring total phenolic compounds (TPCs) using the Folin-Ciocalteu method for variable pH under a commercial LED lamp (45 W). The removal of TPCs was measured at different contact times ranging from 2 h to 6 days. X-ray diffraction (XRD) and transmission electron microscope (TEM) analysis approved the nano size of (5–17 nm) and quasi-spherical morphology of the prepared materials. ICP-OES analysis confirmed the XRD analysis and approved the structure of the prepared materials. Aggregation of the nanomaterials was observed using TEM imaging. Brunauer-Emmett-Teller (BET) analysis measured a 67 m2/g surface area for Fe2Zr2O7. Doping Fe with Mn increased the surface area to 173 m2/g and increased to 187 m2/g with a further increase of the Mn dopant. Increasing the Mn dopant concentration increased both surface area and photocatalytic degradation. The highest degradation of TPCs was observed for Mn2Zr2O7 around 70% at pH 10 and exposure time up to one day.

Application of the central composite design to mineralization of olive mill wastewater by the electro/FeII/persulfate oxidation method

The olive mill wastewater is a major environmental problem, which is waiting for effective treatment. In this study, the mineralization of olive mill wastewater was investigated using the electro/FeII/persulfate process. The central composite design was utilized to examine the effect of each experimental variables (concentration of persulphate and FeII, treatment time and constant current) on the mineralization of olive mill wastewater. The optimum chemical oxygen demand removal percentage was obtained as 71.2% where the reaction conditions were 200 mA current, 250 mM persulphate, 25 mM FeII, and 6 h reaction time. In addition, the maximum percentage of total phenolic removal and the energy consumption were 88% and 4.50 kWh/kgCOD, respectively, which were obtained at the same reaction conditions mentioned above. ANOVA test was used to examine the reliability of the experimental method. The R2 and adjusted R2 coefficients were obtained as 0.9634 and 0.9305, respectively. Optimum experimental parameters were determined and theoretical equations were obtained for the degradation of olive mill wastewater. For the treatment of olive mill wastewater, an environmentally friendly oxidation process was examined and the effect of each experimental variables was clearly demonstrated. The obtained data was optimized for future applications.

Degradation of olive mill wastewater by different methods and antioxidant activity of olive mill wastewater extraction

Olive wastewater (OMW) is an important environmental problem due to the high phenol level and contains organic substances such as sugars, organic acids, polyalcohols, pectins, colloids, tannins, and lipids. Removing OMW is difficult because of the high concentrations of chemical oxygen demand (COD), biochemical oxygen demand, and phenolic compounds. In this study, we concentrated on the degradation of OMW to solve this problem. The degradation of OMW at high pressure and temperature (with H2O2 and without H2O2), at room temperature and atmospheric pressure with H2O2, at room temperature and atmospheric pressure with O3, and with ultrasound-assisted ozonation, was investigated by means of COD, phenolic compounds, and sulfur analyses. The results showed that the method of high pressure and temperature with H2O2 was the most successful. H2O2 at high pressure (O2) and temperature removed 89.2% of COD, 91.5% of phenolic compounds, and color of OMW. With this result, we showed that the use of O2 atmosphere instead of N2 is important for degradation and also especially for color removing. In addition, the antioxidant property of OMW was also examined. Fourier-transform infrared spectroscopy of the extracts revealed vibration bands corresponding to acid, alcohol, and ketone groups. The results showed that high pressure and temperature treatment is very effective for removing phenolic compounds from olive oil wastewater. In addition, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging potential of OMW in the Cukurova area of Turkey was studied and the IC50 value of OMW was determined to be 118 µg/mL.

Heterogeneous Fenton like degradation of olive Mill wastewater using ozone in the presence of BiFeO3 photocatalyst

The possibility of coupling a physicochemical treatment (ozonation) with a heterogeneous Fenton-like using BiFeO3 nanocatalyst for the treatment of olive mill wastewaters (OMW) was investigated. BiFeO3 was successfully synthetized by sol–gel method and structural properties were characterized by X-ray (DRX), scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy FTIR and UV–vis diffuse reflectance spectroscopy.Different degradation systems were considered alone or in combination: Ozone alone, BiFeO3 alone, O3/BiFeO3, O3/H2O2, O3/H2O2/BiFeO3 and O3/BiFeO3/S2O82−.Compared to the other systems, the degradation by O3/BiFeO3/S2O82- in alkaline conditions appeared to be the most efficient, allowing to reach 82.9% and 98.0% reduction of the phenolic compounds and the COD respectively. High stability and reusability of the BiFeO3 particles was shown through four successive oxidation batches, confirming the promising performances of the O3/BiFeO3/S2O82- system.

Inoculum origin and waste solid content influence the biochemical methane potential of olive mill wastewater under mesophilic and thermophilic conditions

The biological valorization of olive mill wastewater (OMW) is often problematic due to the characteristically high organic load and phenolic compound content of this waste stream. The present study aimed at determining the optimal conditions (i.e. temperature, solid content) for the anaerobic digestion of OMW, striving for the maximum methane yield. Therefore, inocula originating from a wastewater treatment plant and two lab-scale bioreactors treating OMW (mesophilic Up-flow Anaerobic Sludge Blanket (UASB) reactor and thermophilic Up-flow Packed Bed Reactor (UPBR)), were tested in terms of OMW degradation potential and methane yield under mesophilic and thermophilic conditions, through Biochemical Methane Potential (BMP) assays. The methane yields were in all cases higher for the raw OMW (325–472 mL CH4/g VSadded) compared to the centrifuged OMW (219–391 mL CH4/g VSadded). Moreover, the greatest biodegradability extent (94.0–98.5%) was achieved by the mesophilic sludge originating from the UASB reactor. The maximum specific methane production rate (121 mL CH4/g VSSadded∙d) was reached by the inoculum obtained from the mesophilic UASB reactor using centrifuged OMW. These results indicate that the mesophilic temperatures are optimal for the anaerobic digestion (AD) of OMW in terms of methane productivity and biodegradation potential, while no solid removal is necessary.

Catalytic Efficiency of Red Mud for the Degradation of Olive Mill Wastewater through Heterogeneous Fenton’s Process

Olive mill wastewater is a challenging effluent, especially due to its toxicity related to the presence of phenolic compounds. Fenton’s process was analysed on the abatement of phenolic acids typically found in this kind of effluents. To overcome the main drawback of Fenton’s process, a waste from the aluminium industry commonly called red mud was used as a heterogeneous source of iron. The adsorption of simulated effluent on the red mud was negligible. Therefore, the degradation of phenolic acids during Fenton’s process was due to oxidation by hydroxyl radicals. The amount of red mud and hydrogen peroxide were optimized regarding phenolic acids degradation. The optimal conditions leading to the highest removal of contaminants (100% of phenolic acids degradation and 25% of mineralization after 60 min of reaction) were 1 g/L of catalyst and 100 mg/L of hydrogen peroxide. The possibility of recovering treated water for agricultural purposes was evaluated by assessing the toxic impact over a wide range of species. The toxicity observed for the treated samples was mainly related to the residual hydrogen peroxide remaining after treatment.

Jet-loop reactor with cross-flow ultrafiltration membrane system for treatment of olive mill wastewater

AbstractOlive oil extraction is one of the ancient agricultural industries all over the Mediterranean area and even today it is of fundamental economic importance for many industries found over the whole Mediterranean. However, this industry generates large amounts of olive mill wastewater (OMW) and due to its physicochemical characteristics it causes severe environmental concerns and management problems in the Mediterranean area, which is facing water scarcity. Technologies to reuse this wastewater will have a high impact at the economic and environmental level. The work presented aims to improve the use of jet-loop reactors technology for the aerobic biotreatment of OMW. A jet-loop reactor (100 L) coupled with an ultrafiltration (UF) membrane (MBR) system (JACTO.MBR_100 L) were tested for the influence of hydraulic parameters on OMW degradation and scale-up to 1,000 L. Chemical oxygen demand and total phenols (TP) decreased notably (up to 85% and 80% removal efficiency, respectively) after the biological treatment. The treated OMW (UF permeate) was evaluated as a source for irrigation and its impact on the soil and plant growth and their quality parameters.

Degradation of olive mill wastewater by the induced extracellular ligninolytic enzymes of two wood-rot fungi

Olive mill wastewater (OMWW) is a major problem in olive oil – producing countries, due to its high organic load and concentration in phenols that are toxic for marine life, plants and soil microorganisms. In the present study, two mushroom species were tested in regard to their OMWW's oxidative capacity, Pleurotus citrinopileatus LGAM 28684 and Irpex lacteus LGAM 238. OMWW (25% v/v) degradation was investigated for several culture conditions, namely pH, agitation speed, nitrogen-based supplements and their concentration. The selected values were pH 6, agitation rate 150 rpm, 30 g L−1 corn steep liquor as nitrogen source for P. citrinopileatus and 20 g L−1 diammonium tartrate for I. lacteus. The two strains performed well in cultures supplemented with OMWW, generating very high titers of oxidative enzymes and achieving more than 90% color and phenols reduction within a 24 days cultivation period. In addition, the amount of glucans present in the fungal biomass was assessed. Hence, P. citrinopileatus and I. lacteus appear as potent degraders of OMWW with the ability to use the effluent as a substrate for the production of biotechnologically important enzymes and valuable fungal glucans.

Removal of phenolic compounds from olive mill wastewater by a Fenton-like system H2O2/Cu(II)—thermodynamic and kinetic modeling

The degradation of olive mill wastewater was investigated by a Fenton-like process using Cu (II) as a catalyst and hydrogen peroxide as an oxidant. Phenolic compounds degradation increased from 43% at 30°C to 62% at 50°C after 65 min treatment. Nonlinear regression methods allowed to accurately describe the experimental results and among the tested models, namely Lewis, Page-modified, Henderson/Pabis, and diffusion models, the most appropriate was found to be the Lewis model. The degradation was found to follow a first-order kinetic and the activation energy was 21 kJ/mol.

Advanced Oxidation of Olive Mill Wastewater OMW by an Oxidative Free- Radical Process Induced With Zero Valent Iron

<p>The degradation of olive mill wastewater (OMW) with hydroxyl radicals generated from zero-valent iron and hydrogen peroxide has been investigated by means of chemical oxygen demand (COD) and phenolic compounds analyses. The mechanism uses zero-valent iron activated by oxygen at room temperature to generate Hydroxyl-free radicals that subsequently oxidize organic constituents and clean wastewater. The effects of the iron mass, the pH and the organic matter concentration have been studied. Our experimental results demonstrate that the continuous presence of oxygen and iron in an acidic solution with a pH 2-4 allows the generation of maximum hydroxyl free radicals. The lack of oxygen prevents oxidative reaction, and then the generation of free radicals cannot occur. Coloration of OMW disappeared and phenolic compound decreased after 40 minutes of reaction time. The results show that Fe<sup>0</sup>/H<sup>+</sup> /air or oxygen, could be considered as an effective alternative solution for the treatment of OMW.</p>

On the independence of hydrogen production from methanogenic suppressor in olive mill wastewater

Anaerobic degradation of olive mill wastewater (OMW) at concentrations ranging from 2 to 100 g/L of chemical oxygen demand (COD) was assessed in batch assays. Methane was the main final product obtained for the lower concentrations tested. For 25 g COD/L, H2 was temporarily produced, albeit H2 depletion occurred, likely due to homoacetogenesis, since acetate was formed concomitantly. Hydrogen was produced and accumulated permanently in the assays containing 50 g COD/L of OMW. Methanogenesis and homoacetogenesis were naturally inhibited, suggesting that hydrogen recovery from OMW can be performed without the addition of methanogenic suppressors such as 2-bromoethanosulfonate. This fact opens new perspectives for the utilization of high OMW concentrations in a two-stage valorisation process combining biohydrogen and biomethane production.

TiO2 supported on sepiolite: Preparation, structural and thermal characterization and catalytic behaviour in photocatalytic treatment of phenol and lignin from olive mill wastewater

This study focuses on structural and photocatalytic degradation of olive mill wastewater (OMW) of TiO2 supported sepiolite catalysts, prepared by a sol–gel method in aqueous solution. To get the TiO2/Sep nanoparticle, the nanocrystalline TiO2 anatase phase on sepiolite was obtained using a sufficient thermal treatment by gradually increasing the temperature from 300, 400 and 500°C with 1h intervals for a total of 3h. Then, the structural features of TiO2/Sep materials were investigated by using different spectral and technical structural analyses with scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), XRF and X-ray diffraction (XRD). The photocatalytic degradation of TiO2/Sep materials has been investigated in OMW by using ultraviolet (UV), hydrogen peroxide (H2O2) and TiO2/Sep nanoparticles together. The influence of pH, catalyst amount and temperature was investigated in all the experiments and the degradation ratios were found to be strongly influenced by all investigated parameters. The photocatalytic degradation of lignin and phenol was favorable at pH 9–11.0. Optimum values of catalyst dose and temperature were found to be 0.25 and 0.50gL−1 and 318K, respectively. In addition, the pseudo-first order model was applied and r2 values were noted from 0.90 to 0.99.

Comparison of batch and fed-batch lipase production from olive mill wastewater by Yarrowia lipolytica and Candida cylindracea

Olive mill wastewater (OMW) is a liquid waste that results in large amounts from the olive oil manufacturing industry. The quality and quantity of OMW constituents are dependent of many factors, such as olives type and maturity, climatic conditions and region of origin, cultivation methods, and technology used for oil extraction. From the 3-phases centrifugation process around 1.6 cubic meters of OMW per ton of olives processed are generated. These liquid wastes present an environmental problem and many solutions have been proposed for it, such as its use as culture medium for different lipolytic yeast strains. The aim of this work is the comparison of batch and fed-batch mode of operation for the lipase production and the OMW degradation by two strains, Yarrowia lipolytica W29 and Candida cylindracea CBS 7869. OMW collected from 3-phase continuous olive mills were used (COD of 30 to 261 g/L). OMW used without dilution was supplemented with ammonium chloride and yeast extract proportionally to the COD values. Batch and fed-batch cultures were conducted in a fermenter of 2 L of capacity at pH 7.2, 500 rpm, with constant or variable aeration rate for batch or fedbatch operation, respectively. Batch operation was more adequate to lipase production than fed-batch for both strains but the difference was more significant for Candida cylindracea that revealed to be the most efficient strain for lipase production. However, the final media of the fed-batch cultures presented lower values of COD and sugars concentration indicating a higher level of organic matter degradation. Fed-batch operation was further optimized and the best results of lipase production and OMW degradation where obtained when the operation started with the batch phase in YPD medium instead of OMW based medium.

Photocatalytic hydrogen production over nanostructured mesoporous titania from olive mill wastewater

In this study, nanostructure mesoporous titania (TiO 2) was prepared using sol–gel method from titanium tetrachloride. The prepared titania was characterized by X-ray diffraction (XRD). The textural and surface analysis was carried out using nitrogen adsorption–desorption technique. Also, the photocatalytic degradation of olive mill wastewater (OMW) with simultaneous hydrogen production was studied. The influence of catalyst dose and pH value of wastewater on the degradation of organic pollutants in wastewater and on the amount of evolved hydrogen was investigated. It was observed that the maximum amount of evolved hydrogen at a TiO 2 dose of 2 g/L and a solution pH value of 3 was (851 mL H 2) 38 mmol after 2 h of reaction. On the other hand, chemical oxygen demand (COD) was reduced by 92%. Based on the obtained results, a new process for H 2 production from wastewater can be achieved by coupling degradation of organic pollutants with photocatalytic H 2 production. The process also provides a method for degradation of organic pollutants with simultaneous H 2 production.

Olive mill wastewater degradation by Fenton oxidation with zero-valent iron and hydrogen peroxide

The degradation of olive mill wastewater (OMW) with hydroxyl radicals generated from zero-valent iron and hydrogen peroxide has been investigated by means of chemical oxygen demand (COD) and phenolic compounds analyses. The effects of the H2O2 dose, the pH and the organic matter concentration have been studied. The optimal experimental conditions were found to have continuous presence of iron metal, acid pH (2.0–4.0), and relatively concentrated hydrogen peroxide (9.5 M). Coloration of OMW disappeared and phenolic compound decreased to 50% of initial concentration after 3 h reaction time. The application of zero-valent Fe/H2O2 procedure permitted high removal efficiencies of pollutants from olive mill wastewater. The results show that zero-valent Fe/H2O2 could be considered as an effective alternative solution for the treatment of OMW or may be combined with a classical biological process to achieve high quality of effluent water.

Degradation of olive mill wastewater by the combination of Fenton's reagent and ozonation processes with an aerobic biological treatment

Degradation of olive mill wastewater (OMW) by means of two chemical oxidation processes (Fenton's reagent and ozonation) and their consecutive treatments with aerobic microorganisms have been studied. Fenton's reagent treatment moderately reduces COD and to a greater extent the polyphenolic compounds. Ozonation contributed to low conversion of COD and moderate reduction of polyphenols. The aerobic biological treatments degrade to values higher than 70% and 90% for COD and polyphenolic compounds, respectively. A kinetic study has been carried out in each process, determining the representative kinetic parameters of each model.

Aerobic degradation of olive mill wastewaters.

The degradation of olive mill wastewater by aerobic microorganisms has been investigated in a batch reactor, by conducting experiments where the initial concentration of organic matter, quantified by the chemical oxygen demand, and the initial biomass were varied. The evolution of the chemical oxygen demand, biomass and the total contents of phenolic and aromatic compounds were followed through each experiment. According to the Contois model, a kinetic expression for the substrate utilization rate is derived, and its biokinetic constants are evaluated. This final predicted equation agrees well with all the experimental data.

Problems of identifying phenolic compounds during the microbial degradation of olive mill wastewater

The main objectives of the presented Spanish-German collaboration are the purification of alpechin by biodegrading phenolic compounds and the investigation of metabolites during fermentation prior to its safe disposal. In addition to 12 well-known compounds, 3,4-dihydroxyphenylglycol was also identified in untreated Spanish and Italian alpechin samples using a GC MS method. The qualitative composition of the Italian and Spanish samples differ. First results of degradation tests of reference substances are reported: Arthrobacter is capable of completely transforming added tyrosol to the corresponding 4-hydroxyphenylacetic acid and after 139h of fermentation no traces of tyrosol can be identified. In contrast, only traces of phenylacetic acid are produced by Bacillus pumilus after 139h of fermentation of tyrosol.

Biodegradación de compuestos fenólicos del alpechín con <i>Aspergillus terreus</i>

Olive mill wastewater degradation by Aspergillus terreus and under aerobic conditions at 28°C, was measured by the parameter of phenol content. We have explored the effect of different concentrations of olive mill wastewater upon the activity of Aspergillus terreus . Through HPLC, 10 phenol compounds (90% of the total phenolic content of the olive mill wastewater) were identified.