Treatment Of Olive Mill Wastewater Research Articles

Valorization of Cherry By-Products as Coagulant/Flocculants Combined with Bentonite Clay for Olive Mill Wastewater Treatment

In this study, two by-products resulting from the processing of cherry (stems and pits) were used as natural coagulants to promote the valorization of these wastes and treat olive mill wastewater (OMW). The efficacy of the plant-based coagulants (PBCs) in the coagulation–flocculation–decantation process (CFD) was evaluated through the removal of turbidity, total suspended solids (TSS), total polyphenols (TPh), and dissolved organic carbon (DOC). The CFD process was demonstrated to be effective in turbidity and TSS reduction in OMW. Using cherry stems (CSs), these reductions were 65.2% of turbidity and 58.0% of TSS, while cherry pits (CPs) achieved higher reductions, 78.6% of turbidity and 68.2% of TSS. To improve the effectiveness of OMW treatment, mainly regarding the removal of TPh and DOC, the CFD process was complemented with the adsorption process (using bentonite clay). The adsorption capacity of bentonite was higher in acidic conditions (pH 3.0) and, with a dosage of 3.0 g L−1, reached 17.3 mg of DOC and 13.8 mg of TPh per gram of bentonite. Several adsorption isothermal models were assessed, and the Langmuir (r2 = 0.985), SIPS (r2 = 0.992), and Jovanovic models (r2 = 0.994) provided the best fittings. According to the optimal operational conditions defined throughout the present work, the combination of CFD and adsorption removals were as follows: (1) 98.0 and 91.3% of turbidity, (2) 80.8 and 81.2% of TSS, (3) 98.1 and 97.6% of TPh and (4) 57.9 and 62.2% of DOC, for CSs and CPs, correspondingly. Overall, the results suggest that cherry by-products can be used as low-cost natural coagulants and, when combined with another natural, abundant, and cheap material, such as bentonite clay, can be a sustainable alternative for treating OMW.

Environmental and economic analysis of an olive mill wastewater treatment system integrated with microalgae production

Environmental and economic analysis of an olive mill wastewater treatment system integrated with microalgae production

Treatment of olive mill wastewater by coagulation–flocculation with aluminum sulphate / aluminum polyhydroxichlorosulfate and effect on phytotoxicity

In the present study, coagulation floculation was examined using two different coagulants: aluminum sulphate (Al2(SO4)3) which is widely used on an industrial scale for olive mill wastewater (OMW) treatment, and polyhydroxichlorosulfate aluminum (Aln OHm Cl3n-m-2k (SO4)k) popularly known as WAC. The coagulant WAC is already used in the treatment and purification of water, but it has never been tested for the treatment of OMW. The phytotoxicity study of OMW (before and after treatment) to wheat seeds showed that the toxic compounds of this effluent affect both the seed germination and the seedling growth. The root length was more sensitive to OMW than the shoot length. However, the toxicity of this effluent has been greatly reduced after treatment with WAC (growth was inhibited at concentration of 80 %) compared to another OMW treated with aluminum sulfate. The highest percentages of germination have been observed in the seeds irrigated by OMW treated with WAC. This study also showed that the phytotoxicity decreased with dilution (5–40 % for raw OMW, 5–50 % for OMW treated with aluminum sulfate, and 5–60 % for OMW treated with WAC). Finally, the experimental results obtained show that the dilution and the treatment by the WAC coagulant (2.50 g; pH between 6.50 and 7.50) are two important processes to reduce the phytotoxicity effect of OMW.

Innovative entrapped Yarrowia lipolytica within polyvinylpyrrolidone (PVP)/polyethylene glycol (PEG) /agar for improving olive mill wastewater bioremediation

To date, treated olive mill wastewater (OMW) remains expensive and challenging due to its acidity and high levels of hazardous compounds, which cause significant environmental concerns. Consequently, it is crucial to develop an eco-cleaner and effective method for treating OMW. Herein, the novel immobilization of Yarrowia lipolytica within a polyvinylpyrrolidone (PVP)/polyethylene glycol (PEG)/agar matrix was prepared as a bio-tool to enhance OMW treatment. The immobilized Y. lipolytica was characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Our results indicated that the immobilized Y. lipolytica significantly improved removal efficiencies, reducing 88.6% of COD, 98.05% of TKN, 92.64% of turbidity, 75% of lipids, and 32.08% of PO4−3 after 72 h. Interestingly, the removal efficiency increased upon reusing immobilized cells for three cycles, reaching 93.33%, 100%, and 98.73% for COD, TKN, PO4−3, and turbidity, respectively, after 72 h, along with valuable biomass production of 7.31 g L−1. Furthermore, correlation analysis and predictive modelling confirmed the effectiveness and recyclability of this process.

Olive mill wastewater co-treatment: Effect of (electro)Fenton processes and dilution ratio on moving bed biofilm reactor performance

The treatment of olive mill wastewater (OMW) represents still an open challenge because of its highly polluting load. One of the most affordable methods for small-medium mills is to send OMW to industrial wastewater treatment plants (IWTP). Accordingly, this work explored a strategy consisting of the biological co-treatment of real OMW and simulated urban wastewater by a moving bed biofilm reactor (MBBR), with and without (electro)Fenton pre-treatment, to simulate OMW treatment through a multi-barrier approach in an IWTP. The effluent of the MBBR without pre-treatment, despite the long period of operation of 18 months, was in compliance with the limit for total phenols (TPHs) of 0.5 mg/L only at a really low OMW's dilution ratio (DR) (1/4000 (v/v)). The Fenton oxidation (FO) and the electro-assisted Fenton (EAF) processes were investigated as pre-treatment of diluted OMW. FO resulted in good performances in terms of TPHs removal (81%) and improved biodegradability (final BOD5/COD ratio = 0.35) but in poor COD removal (24%). EAF was more effective (COD removal = 41%, TPHs removal = 85%, and final BOD5/COD ratio = 0.40) than FO. Therefore, EAF was finally investigated on undiluted OMW (COD removal = 56%, TPHs removal = 84%, and final BOD5/COD ratio = 0.62) and subsequently co-treated with simulated urban wastewater by MBBR, identifying 1/1000 as the optimal DR. The investigated multi-barrier approach is an interesting option for OMW co-treatment in IWTPs to successfully address the challenge of TPHs degradation and drastically reduce the volume of the biological process unit (4 times lower than MBBR treatment alone).

Centrifugation Effect on Olive Mill Wastewater Treatment by Coagulation-Flocculation Using Ca(OH)2-Pectin System

Centrifugation Effect on Olive Mill Wastewater Treatment by Coagulation-Flocculation Using Ca(OH)2-Pectin System

Mechanosynthesis, characterization, and adsorptive properties of Mg–Al-LDH and Zn–Al-LDH for olive mill wastewater treatment

Mechanosynthesis, characterization, and adsorptive properties of Mg–Al-LDH and Zn–Al-LDH for olive mill wastewater treatment

Modeling and Optimization of a Green Process for Olive Mill Wastewater Treatment

The olive mill wastewater (OMW) treatment process is modeled and optimized through new design of experiments (DOE). The first step of the process is coagulation–flocculation using three coagulants (modeled with the mixture design) followed by photo-degradation (modelled with the full factorial design). Based on this methodology, we successfully established a direct correlation between the system’s composition during the coagulation–flocculation step and the conditions of the photo-catalytic degradation step. Three coagulants are used in this study, Fe3+ solution, lime, and cactus juice, and two parameters are considered for the photo-degradation conditions: dilution and catalyst mass. Utilizing a sophisticated quadratic model, the analysis of the two observed responses reveals the ideal parameters for achieving maximum efficiency in coagulation–flocculation and photo-degradation processes. This is attained using a quasi-equal mixture of limewater and cactus juice, exclusively. To achieve an optimal photo-catalytic degradation, it is essential to maintain a minimal dilution rate while employing an elevated concentration of TiO2. It was found that the experimental tests validations were in good concordance with the mathematical predictions (a decolorization of 92.57 ± 0.90% and an organic degradation of 96.19 ± 0.97%).

The role of added oxidising agents in assisting the photocatalytic treatment of olive mill wastewater using a metal-free g-C3N4 optical semiconductor

Olive mill wastewaters (OMW) consist of high organic contents and are harmful to aquatic and terrestrial biota. Heterogeneous photocatalysis is a technology that can be operated under mild conditions to remove pollutants in the liquid phase. In the present work, graphitic carbon nitride (g-C3N4, hereafter referred to as GCN) is studied for the first time as a metal-free photocatalyst for OMW treatment. The integration with peroxidation (H2O2), Fenton (Fe2+/H2O2 at both acidic and natural pH), chlorination (HOCl/ClO−) or persulfate (PS) activation is also investigated. This catalyst potentiated the activation of these oxidants, and H2O2 was identified as the best option to achieve high removals of total phenolic content – TPh (87.5 ± 0.3 %), dissolved organic carbon – DOC (63.8 ± 0.4 %) and chemical oxygen demand – COD (87.7 ± 0.6 %), without need to add iron or adjust the pH. The stability and reusability of the GCN material in the H2O2-assisted photocatalytic treatment of OMW give rise to new possibilities for treating these waste waters.

A remarkable step in the aerobic biological treatment of Olive Mill Wastewater (OMW): A combination of selected microbial strains that enhance their decolorization and depollution

The olive industry extracts oil from olives but also generates solid co-products called pomace and liquid wastes known as Olive Mill Wastewater (OMW). With global annual production exceeding 30 million tons and approximately 685,000 tons in Morocco alone, these wastes pose environmental challenges due to their high acidity, organic load, and phenolic compounds. Our research aims to depollute and recycle OMW using aerobic biological treatment methods. Samples were collected from various ecological sites across four Moroccan regions. We isolated and purified several strains of molds, yeasts, and bacteria capable of decolorizing OMW. Decolorization experiments revealed promising results, with a combination of seven selected molds showing significant reductions in chemical oxygen demand (COD) by 71.44%, biochemical oxygen demand (BOD5) by 69.91%, and polyphenols content by 84.22%. Encouraged by these findings, we propose further treatment using sourdoughs composed of combinations of different pure strains, including yeasts and selected bacteria such as Bacillus subtilis and Pseudomonas aeruginosa. This approach demonstrates a practical and cost-effective method for depolluting and recycling OMW, contributing to environmental protection and human health preservation. By mitigating the risks associated with untreated OMW discharge, this study offers a viable solution to the environmental challenges posed by olive processing industries globally, particularly in regions like Morocco where olive cultivation is significant.

Alternative treatment of olive mill wastewater by combined sulfate radical-based advanced electrocoagulation processes.

The aim of this study is to investigate the performance of advanced electrocoagulation (EC) process for the treatment of olive mill wastewater. In EC process, iron plates were used as electrodes, and peroxydisulfate (PS) and peroxymonosulfate (PMS) were added as oxidants. The effects of the initial pH value, current density, oxidant dose, and electrolysis time were optimized for pollutant removal from olive mill wastewater by EC-PS and EC-PMS processes. Control experiments showed that addition of oxidants to the conventional EC process increased the pollutant removal efficiency. Classical optimization method was used to determine optimum conditions, which were initial pH4, current density 40 mA/cm2 , oxidant dose 5g/L, and electrolysis time 30 min for both processes. Under these conditions, EC-PS and EC-PMS processes achieved 50.5% and 48.9% chemical oxygen demand (COD), 93.8% and 89.3% total phenol, 87.7% and 83% UV254 , and 74.5% and 64.1% total suspended solid removal efficiencies. Quenching experiments were performed to determine the dominant radical species participating in the processes. It was observed that hydroxyl and sulfate radicals were involved in both processes but hydroxyl radicals were more active. Specific energy consumption was calculated as 5.90 kWh/kg COD for EC process, 4.95 kWh/kg COD for EC-PS process, and 5.20 kWh/kg COD for EC-PMS process. The organic removal/sludge ratio of EC-PS process was found to be higher with 17.5g/L value. Although the application of EC-PS and EC-PMS processes alone is insufficient to meet the discharge limits, they have been found to be effective in olive mill wastewater treatment. PRACTITIONER POINTS: Peroxydisulfate (PS) and peroxymonosulfate (PMS)-based advanced electrocoagulation (EC) was used in olive mill wastewater treatment. 50.5% chemical oxygen demand (COD), 93.8% TP, 87.7% UV254 , and 74.5% TSS removals were achieved by EC-PS. 48.9% COD, 89.3% TP, 83% UV254 , and 64.1% TSS removals were obtained by EC-PMS. Hydroxyl and sulfate radicals were involved in both processes.

Winery and olive mill wastewaters treatment using nitrilotriacetic acid/UV-C/Fenton process: Batch and semi-continuous mode

In this work, both red and white winery wastewaters (WW) and olive mill wastewater (OMW) were submitted to a treatment by Fenton-based processes (FBPs). The main aim was to evaluate the most efficient and economic process. Initial tests, resorting to a batch reactor, demonstrated that UV-C/Fenton (λ = 254 nm) was the most effective process. Operational conditions such as pH, H2O2 and Fe2+ concentrations revealed to have a superior influence within dissolved organic carbon (DOC) removal as well as regarding the reactor's energy consumption. As a means to prevent iron precipitation, the addition of nitrilotriacetic acid (NTA) was tested. With experimental conditions pH = 3.0, [H2O2] = 194 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), time = 240 min, the kinetic rate related with DOC removal showed a kredWW = 0.0128 min−1 > kOMW = 0.0124 min−1 > kwhiteWW = 0.0104 min−1 and both the WW and OMW achieved the Portuguese legal limit values for wastewater discharge. Furthermore, comparative experiments were performed in a semi-continuous reactor, being that the results put in evidence that the concentration of H2O2 added and the flow rate of reagents' addition (F) had a significant effect on the efficiency of the reactor. Under an optimum experimental procedure pH = 3.0, [H2O2] = 97 mM, [Fe2+] = 1.0 mM, [NTA] = 1.0 mM, radiation UV-C (254 nm), F = 1 mL min−1, time = 240 min, there were observed higher DOC removal kinetic rates (kOMW = 15.20 × 10−3 min−1 > kredWW = 11.64 × 10−3 min−1 > kwhiteWW = 11.57 × 10−3 min−1) and a cost ranging between 0.0402 and 0.0419 €/g.DOC. These results showed that semi-continuous reactors have the potential to be applied to large scale treatments, with low reagents consumption and reduced energy requirements.

Olive mill wastewater treatment using natural adsorbents: phytotoxicity on durum wheat (Triticum turgidum L. var. durum) and white bean (Phaseolus vulgaris L.) seed germination.

This research was undertaken to optimize the phenolic compound removal from Olive Mill Wastewater (OMW) by sawdust and red clay as natural adsorbents. Fractional factorial experimental design at 25-1 was used in order to optimize the experimental conditions for high removal efficiency. Statistics ANOVA analysis, Fisher's test, and Student's test suggested that the adsorbent dose has the most significant influence on polyphenol removal for both adsorbents. The maximum removal of polyphenols by sawdust reached 49.6% at 60 °C by using 60 g/L of adsorbent dose, pH 2, reaction time of 24 h, and agitation speed of 80 rpm. Whereas, for red clay, 48.08% of polyphenols removal was observed under the same conditions for sawdust except the temperature of 25 °C instead of 60 °C. In addition, the thermodynamic parameters suggested spontaneous process for both adsorbents, endothermic for the sawdust and exothermic for red clay. Furthermore, the phytotoxicity effect of OMW on durum wheat (Triticum turgidum L. var. durum) and white bean (Phaseolus vulgaris L.) seed germination was investigated. The obtained results showed that the untreated OMW inhibited the seed germination of T. turgidum and P. vulgaris seeds. OMW treatment with red clay followed by dilution (95% water) resulted in 87 and 30% germination of P. vulgaris and T. turgidum, respectively. While, the treatment of OMW with sawdust and dilution at 95% resulted in 51 and 26% germination of P. vulgaris and T. turgidum, respectively.

Uncovering applicability of Navicula permitis algae in removing phenolic compounds: A promising solution for olive mill wastewater treatment

This work identifies Navicula permitis, freshwater diatom algae, by analyzing its 18S DNAr and testing how well it could grow and remove phenolic compounds at varying concentrations from 50 to 250 mg/L. The changes in the culture's chlorophyll fluorescence were measured when being exposed to stress. The biodegradation of phenolic compounds was tested by analyzing the enzyme activities of phenol hydroxlase and catechol dioxygenase in N. permitis. It was found that N. permitis could withstand up to 145.9 mg/L of phenol concentration. The response surface methodology was used to optimize conditions for N. permitis to degrade phenol with 50.08 mg/L of concentration, 106 cells/mL of N. permitis, and 11.38 days of treatment. Phenol removal by the Navicula permitis followed a zero-order kinetic model, and N. permitis used PHase to breakdown the pollutant. The ortho-pathway played a role in phenol metabolism. While degrading phenol, N. permitis produced biomass, which makes it a promising option for environmental remediation.

Aerated lagoon/adsorption combination method for the treatment of olive mill wastewater: optimizing parameters using study design.

The current study focuses on investigating how to improve the efficacy of the combined process of aerated lagooning and adsorption for the treatment of olive mill wastewater (OMWW) from the olive industries in the Loukkos region using the design of experiments approach. The latter made it possible to optimize the experimental conditions, such as the mass concentration of lime, the mass concentration of powdered activated carbon (AC), and the speed of agitation (Va), which are required for the envisaged treatment, in order to control the results after the evaluation of the necessary physicochemical parameters, namely pH, total suspended solids (TSS), chemical oxygen demand (COD), rate of discoloration, and content of polyphenols. The experimental conditions necessary to carry out this study were between 1.4 and 1.75 g/l for AC, between 23 and 32 rpm for the stirring speed, and between 0.88 and 1.3 g/l for the mass concentration of lime. The results of this experiment showed that treating OMWW with the prototype II after adding lime to the mixture resulted in an estimated 85% reduction in the analyzed parameters. The pH, TSS, COD, discoloration rate, and polyphenol content were all reduced from initial values of 4.87, 0.63 (g/l), 80.3 (g (O2/l)), 0.8%, and 1.45 (g/l), respectively, to final values of 6.92, 0.12 (g/l), 12, 0.16%, and 0.25 (g/l). These results are highly significant when compared to those obtained during the treatment of prototype I using only powdered activated carbon, which showed a reduction rate of around 70%.

The biochemical and electrochemical characteristics of a microbial fuel cell used to produce electricity from olive mill wastewater

Olive Mill Wastewater (OMW) is a hard to treat by-product with low biodegradability and high toxicity due to its high phenolic content. Ιn the present study, OMW after centrifugation, was used for combined electricity and methane production. A three-air cathode single-chamber MFC operating continuously was set up for the exploitation of the liquid fraction of OMW obtained via centrifugation, while batch anaerobic digestion (AD) was employed for valorization of the solid residue. The MFC was also operated with a glucose-based medium, supplemented with phenolics, in order to assess the effect of phenolic compounds on its performance. In order to highlight the mechanisms and determine the limitations and electrochemical losses, electrochemical impedance spectroscopy experiments were conducted, using both the synthetic and the real wastewater. The experimental results showed that power densities of 0.7–2.0 W/m3 OMW were achieved in the MFC, corresponding to an energy of 6.2 MJ/m3 OMW while 664 MJ/m3 OMW could be obtained through AD of the solid residue. However, as the energy which could be recovered directly from AD of OMW was calculated as 1439 MJ/m3 OMW, indicates that it is a competitive technology for OMW treatment and valorization.

A review on Processes for olive mill waste water treatment

A review on Processes for olive mill waste water treatment

Hybrid treatment of olive mill wastewater by iron-catalyzed percarbonate and peroxymonosulfate oxidation followed by electrooxidation

In this study, hybrid advanced oxidation processes were applied to effectively treat olive mill wastewater (OMW). In the first stage of the hybrid process, Fe2+-activated peroxymonosulfate (PMS) and percarbonate (PC) oxidation processes were applied. Optimum conditions for maximum chemical oxygen demand (COD), ultraviolet absorbance at 254 nm (UV254), and color removal were determined. Since the difference between the removal efficiencies of the two processes was negligible, the Fe2+-activated PC process was selected. Under optimum conditions (pH: 4, PC dose: 10 g/L, Fe2+ dose: 5 g/L, reaction time: 60 min) with the Fe2+-PC process, 43.3 % COD, 69.4 % UV254, and 88.6 % color removal were obtained. In the second stage, the electrooxidation (EO) process was applied to the effluent of the Fe2+-PC process. Different anode materials were evaluated in EO based on their pollutant removal efficiency, specific energy consumption, anode efficiency, and instantaneous current efficiency, and IrO2-coated Ti (Ti/IrO2) was selected. In the EO process using Ti/IrO2 anode, 1.75 A, pH 3.5, and 120 min, 59.6 % COD, 94.5 % UV254, and 100 % color removal efficiency were achieved. A total of 77.1 % COD, 98.3 % UV254, and 100 % color removal efficiencies were obtained with hybrid processes, and it was seen that hybrid advanced oxidation is an effective application in removing pollutants from OMW.

Enhancing Nature-Based Solutions: Efficient Removal of Hydroxytyrosol in Olive Mill Wastewater Treatment for Value Creation

This study aimed to investigate the potential use of the microalgae Chlorella sorokiniana and Scenedesmus quadricauda for the bioremediation of olive mill wastewater (OMW), which is a major environmental issue and a waste product of olive oil production. The study investigated the effects of different dilutions (10% and 50%) of OMW on the growth of the microalgae and their ability to remove the phenolic component hydroxytyrosol (OH-Tyr) and enhance their antioxidant properties. The results indicated that, although the growth on OMW was not enhanced, both microalgae strains were able to remove OH-Tyr from OMW, with Chlorella sorokiniana showing higher removal efficiency than Scenedesmus quadricauda. Moreover, the antioxidant activity of the microalgal extracts increased after 96 h of exposure to OMW. These findings suggest that microalgae-based treatment of OMW could be a promising approach for the bioremediation of this waste product and the production of value-added products. Overall, the use of microalgae for the treatment of OMW could provide a sustainable solution for the management of this waste product while generating potential economic benefits for olive producers.

Mathematical Modeling of Pilot Scale Olive Mill Wastewater Phytoremediation Units

A mechanistic state–space model has been developed to describe the dynamics of olive mill wastewater (OMW) treatment in phytoremediation pilot units with P. granatum L. and M. communis L. plants and to assess further the relative contribution of the plants in the overall OMW remediation process. Both phytoremediation and bioremediation processes have been considered in the model, i.e., phytodegradation, rhizodegradation, accumulation of hardly biodegradable organic matter on the root tissue of plants, microbial growth, maintenance and decay, and enzymatic decomposition of organics. Maximum specific microbial growth rates for bacteria and fungi were estimated within the range of 0.164–0.236 1/h. The specific rate for the decomposition of hardly biodegradable organics both by bacteria and fungi was within the range of 10.75–72.73 mg-substrate/g-biomass·h, whereas, particularly for the high-molecular-weight polyphenols, it was 1.02–18.25 mg-substrate/g-biomass·h. The values of the transpiration stream concentration factor were greater than 0.95 for both the non-phenolic and phenolic organics, which indicates almost passive uptake of OMW organics’ mixture by the plants. The corresponding factors for inorganic N and P were estimated as greater than unity, indicating active uptake. Overall, the model predicts the experimental data well when the organic concentration of OMW is high, and it predicts that phytoremediation processes contribute by more than 91% to the removal of OMW organics and nutrients, irrespective of the wastewater organic strength.