Treatment Of Olive Mill Wastewater Research Articles

Treatment of olive mill wastewater by adsorption of phenolic compounds

Treatment of olive mill wastewater by adsorption of phenolic compounds

Impact of ultrasonic pretreatment on Fenton-based oxidation of olive mill wastewater - towards a sustainable treatment scheme

This study evaluated the potential of ultrasonic enhanced Fenton-based advanced oxidation to reduce toxicity, total phenol (TPh) and organic matter (COD) from olive mill wastewater (OMW). Emphasis was also placed on suggesting a sustainable treatment strategy in the light of accumulated scientific evidence, indicating the role of Fenton-based oxidation in the suggested scheme. Fenton oxidation and Fenton-like oxidation (with Fe2+ and Fe3+) were tested as selected advanced oxidation methods. The experiments were conducted in such a way that the individual removal efficiencies of ultrasonication and advanced oxidation processes be evaluated separately and in sequence. The impact on toxicity removal was tested by means of a standard respirometric method, also currently used to assess biodegradation in wastewaters. Response Surface Methodology (RSM) involving central composite design (CCD) was implemented to assess the optimum conditions. Results highlighted the merit of Fenton-based oxidation with an 80% TPh reduction and a decrease of toxicity down to the narrow margin of 13–17%, together with a COD reduction of 20–26%, all quite meaningful for the following step of biological treatment. The ultrasonic pretreatment also proved to be quite useful as it secured up to 40% of particulate COD dissolution. Studies on particle size distribution of the OMW clearly showed that preliminary treatment including advanced oxidation would leave behind the bulk of soluble COD accumulated below the size of 3 nm. Accordingly, co-treatment of OMW diluted with municipal sewage was recommended after a pretreatment sequence of holding/plain settling; chemical treatment and Fenton-based oxidation. For OMWs with low particulate COD (VSS) content, Fenton-based oxidation enhanced by ultrasonic pretreatment would be a viable option in the view of effective particulate COD dissolution achieved in this study when coupled with ultrafiltration, prior to joint biological treatment with sewage. The study highlighted advanced oxidation as an indispensable step in the treatment of olive mill wastewaters.

Performance and dynamic modeling of a continuously operated pomace olive packed bed for olive mill wastewater treatment and phenol recovery

The solid waste of olive oil extraction processes (olive pomace, OP) was converted into activated carbon (AC) by treating it with NaOH and then encapsulating it within sodium alginate (SA) in beads by crosslinking (SA-AC beads). The prepared SA-AC beads were utilized as an adsorbent for the elimination and recovery of phenolic compounds (PCs) from olive mill wastewater (OMWW) following a zero liquid and waste discharge approach to implement and promote the circular economy concept. The novel AC and SA-AC beads were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET) analysis. The adsorption performance of these beads was evaluated in batch and fixed-bed reactors operated in a concurrent flow system. The results revealed that an adsorption capacity of 68 mg g−1 was attained for 4000 mg L−1 phenolic compounds. The kinetics of the adsorption process of the PCs fit a pseudo second-order model, and the most likely mechanism took place in two stages. The adsorption isotherm conformed to the Langmuir model, representing the monolayer adsorption of the phenolic compounds. The dynamic models were used, and they accurately represented the breakthrough curves. Considering PC recovery and process reusability, a regeneration experiment of SA-AC beads was carried out in fixed-bed reactors. SA-AC beads showed a high percentage desorption >40% using ethanol and were efficient after several cycles of OMWW treatment and phenol recovery.

Heterogeneous Photo-Fenton Reaction for Olive Mill Wastewater Treatment—Case of Reusable Catalyst

Heterogeneous catalysts can be an efficient and economical option for olive mill wastewater (OMW) treatment by an advanced oxidation process if they could be reused. In this work, OMW was treated using a heterogeneous photo-Fenton reaction (artificial ultraviolet light/H2O2/HFeO2). For this purpose, different concentrations of HFeO2 were tested: 0.04; 0.3; 0.8; 5.0; 10.0; 20.0; 30.0, and 50.0 g/L. The following operational conditions were chosen: pH = 3.0, temperature = 20 °C, agitation rate = 700 rpm. The experimental results showed high removal percentages of the main OMW characterization parameters at 50 g/L of HFeO2: %CODremoval = 62.8%; %total phenolic compounds (TPCs) = 88.9%. These results were also compared with those of other control oxidation systems, i.e., UV, H2O2, and UV/H2O2, which provided 35.5 and 56.1%; 46.2 and 74.0%; 48.0 and 76.8% removal, respectively. In addition, the catalyst was reused three times, recovering more than 90.5% of it.

Multi-Response Optimization of Coagulation and Flocculation of Olive Mill Wastewater: Statistical Approach

Olive oil production is one of the important industrial sectors within the agro-food framework of the Mediterranean region, economically important to the people working in this sector, although there is also a threat to the environment due to residues. The main wastes of the olive oil extraction process are olive mill wastewater (OMW) and olive husks which also require proper treatment before dismissal. In this research work, the main goal is to introduce grey relational analysis, a technique for multi-response optimization, to the coagulation and flocculation process of OMW to select the optimum coagulant dosage. The coagulation and flocculation process was carried out by adding aluminum sulfate (Alum) to the waste stream in different dosages, starting from 100 to 2000 mg/L. In previous research work, optimization of this process on OMW was briefly discussed, but there is no literature available that reports the optimal coagulant dosage verified through the grey relational analysis method; therefore, this method was applied for selecting the best operating conditions for lowering a combination of multi-responses such as chemical oxygen demand (COD), total organic carbon (TOC), total phenols and turbidity. From the analysis, the 600 mg/L coagulant dosage appears to be top ranked, which obtained a higher grey relational grade. The implementation of statistical techniques in OMW treatment can enhance the efficiency of this process, which in turn supports the preparation of waste streams for further purification processes in a sustainable way.

Effects of High Voltage Electrical Discharge Plasma on Olive Mill Wastewater Treatment

High voltage electrical discharge plasma technology (HVED) is considered as a promising technology for wastewater remediation due to its fast removal rate and environmental compatibility. Olive mill wastewater (OMWW) treatment presents crucial environmental issues because of its high organic load and intense toxicity and phytotoxicity. The effect of cold plasma at frequencies of 60 Hz and 120 Hz, with injected gas (air, oxygen and nitrogen) and with and without the addition of FeCl3x6H2O, during 30 min, on degradation and removal of organic compounds, as well as polyphenols from OMWW, were investigated. The efficiency of cold plasma was monitored by pH, temperature, electroconductivity, redox potential, oxygen saturation and reduction of chemical oxygen demand (COD) and polyphenols. The best removal efficiency of 50.98% of organic compounds was achieved at 120 Hz with nitrogen and the addition of FeCl3x6H2O, and a 60.32% reduction of polyphenols at a frequency of 60 Hz with the air and FeCl3x6H2O added was obtained. Also, the plasma treatment resulted in a decrease in coloring intensity, with the most significant color change at 120 Hz with the addition of FeCl3x6H2O with nitrogen and air.

Effectiveness assessment of olive mill wastewater treatment by combined process: Natural flotation and anaerobic‐aerobic biodegradation

AbstractThe present work intends to study the treatment of olive oil mill wastewater (OMW) by natural flotation followed by anaerobic‐aerobic biodegradation, without dilution. After natural flotation, turbidity, chemical oxygen demand (COD) and polyphenol decreased by 37.7%, 3.7% and 3.3%, respectively. Whereas, anaerobic treatment removed 23.9% of nitrate, 29.1% of turbidity and 16.2% of polyphenol. However, intermittent aeration treatment showed the reduction of nitrate, turbidity and ammonium by 90%, 26.5% and 65.1%, respectively. In general, the combined natural flotation and anaerobic‐aerobic treatment of OMW, without dilution, have led to reduced turbidity, COD, polyphenol, nitrate, ammonium and phosphorus by 67.5%, 29.1%, 25.2%, 93.9%, 77.1% and 81.8%, respectively. The germination index of the treated OMW was 69% after 30% of dilution. Finally, the proposed treatment process could be used in small and medium‐sized industries as a simple, economical and effective method. Also, the produced water could be reused for irrigation.

Candida tropicalis as a Promising Oleaginous Yeast for Olive Mill Wastewater Bioconversion

Olive mill wastewater (OMW), which is generated during olive oil production, has detrimental effects on the environment due to its high organic load and phenolic compounds content. OMW is difficult to biodegrade, but represents a valuable resource of nutrients for microbial growth. In this study, yeast strains were screened for their growth on phenolic compounds usually found in OMW and responsible for antimicrobial effects. Candida tropicalis ATCC 750 demonstrated an extraordinary capacity to grow in phenolics and was chosen for further experiments with OMW-based medium. The effects of nitrogen supplementation, the pH, and the stirring rate on cellular growth, OMW-components consumption, and added-value compounds production were studied in batch cultures in Erlenmeyer flasks and in a bioreactor. Candida tropicalis was able to reduce 68% of the organic load (chemical oxygen demand) and 39% of the total phenols of OMW in optimized conditions in bioreactor experiments, producing lipase (203 U·L−1) and protease (1105 U·L−1). Moreover, intracellular lipids were accumulated, most significantly under nitrogen-limited conditions, which is common in this type of wastewater. The high potential of C. tropicalis to detoxify OMW and produce added-value compounds from it makes this process an alternative approach to other conventional processes of OMW treatment.

Rapid photocatalytic treatment of high-strength olive mill wastewater by sunlight and UV-induced CuCr2O4@CaFe–LDO

An efficient and cost-competitive hybrid CuCr2O4@CaFe–LDO catalyst was successfully synthesized for the decontamination of olive mill wastewater. CuCr2O4@CaFe–LDO has a bandgap of 2.56 eV, exhibited stable photocurrent response of ∼4.48 μA cm–2, possesses a wide range of pores with an average size and pore surface area of 12.51 nm and 8.25 m2 g–1, respectively. The constituent elements and optical activity of the CuCr2O4@CaFe–LDO were established by an X-ray photoelectron spectroscopy and diffuse reflectance UV–vis spectroscopy, respectively. Under optimized conditions; 50 mg CuCr2O4@CaFe–LDO achieved 54.8 % degradation of phenolics after 4 h without an oxidant in the dark, while 90 % degradation was attained within 40 min with sunlight-assisted irradiation in the presence of 0.05 M K2S2O8. Under UV assisted system, CuCr2O4@CaFe–LDO/K2S2O8 consumed 19.22 kW h m−3 (0.96$) electrical energy with an apparent rate constant, kapp =0.00598 min−1 within 120 min which resulted to 99 % degradation of the phenolics, 95.1 % COD removal (%) and 84.6 % BOD removal efficiency. The spent catalyst was rapidly recovered from the bulk solution due to its sufficient saturation magnetization of 54.7 emu g−1 and retained 93 % reuse efficiency after four consecutive recycling tests. The multiprocess mechanism was established considering the contribution of active species (OH, SO4−, h+ and O2−).

Integration of olive stones in the production of Fe/AC-catalysts for the CWPO treatment of synthetic and real olive mill wastewater

A by-product of olive mill’s operation (olive stone, OS) was transformed into activated carbon (AC) and used as support to prepare Fe-based catalysts, which were employed on the catalytic wet peroxide oxidation (CWPO) of olive mill wastewater (OMW). Three Fe-impregnation routes were tested: incipient wetness impregnation (IWI), adsorption (Ads), and hydrothermal (HT), resulting in catalysts with distinct iron loadings, particle sizes and surface dispersion. OSAC-Fe catalysts were characterized by N2 and CO2 physisorption, XRD, XPS, FTIR, HRTEM, EDX, and HRSEM techniques. Catalysts’ activity and stability was first compared in the degradation of synthetic polyphenolic solutions. After one cycle (240 min), catalysts’ sorption capacity was considerably exhausted and OH radicals were found to be the main oxidative species responsible for total phenolic content (TPh) removal. OSAC-Fe-IWI and OSAC-Fe-Ads performed better than OSAC-Fe-HT after four consecutive cycles (53 and 48 vs. 38% TPh removals, respectively), also showing considerably lower cumulative Fe leaching values (2.2 and 2.8 vs. 10 wt%). The most promising materials were used for depuration of real OMW samples. Under smooth operational conditions ([OSAC-Fe-IWI] = 2.0 g/L, [H2O2] = 0.5 g/L, pH0 ~ 4.9, T0 = 25 °C), 55% TPh removal was attained after 240 min, resulting in a significant reduction of the effluent’s toxicity (from 100% Vibrio fischeri bioluminescence inhibition to 36%), 37% chemical oxygen demand degradation, and 21% total organic carbon mineralization. Promising catalytic performances were also achieved by OSAC-Fe-Ads, despite its considerably lower iron loading, highlighting the importance of Fe surface dispersion.

Microalgae cultivation by uncoupled nutrient supply in sequencing batch reactor (SBR) integrated with olive mill wastewater treatment

The growth of bacteria contaminants can be controlled in heterotrophic microalgae cultures by using an uncoupled supply of glucose and nitrate. However, till now this strategy was only described for fed-batch cultivation. The cultivation in a sequencing batch reactor (SBR) could be more promising for the industrial scale.Here in this work, we tested the uncoupled supply of substrates on microalgae cultivated in SBR (feast/famine ratio = 1.33), with an optimized culture medium (based on the microalgae elemental formula), and the integration of this strategy with olive mill wastewater (OMW) treatment. SBR allowed to attain biomass productivities (PX) proportional to the initial biomass concentration (PX = 0.13·X0), showing the possibility to reach the same productivities as conventional axenic cultures, by maintaining bacteria contamination at negligible values (<5%, as CFU/algae). The SBR system showed a stable biomass production (1.54 folds X0) throughout 8 consecutive cycles (53 days), uncoupling biomass production and cell duplication. However, relevant grazer contamination reduced the growth of microalgae cells between the 4th and 7th cycle and the biomass yield on glucose (from 0.31 to 0.17 g g−1). The integration with OMW treatment proved the possibility to remove 52% of phenols, but the loss of fermentable substrates during OMW storage and preliminary processing (by membrane filtration) hindered the exploitation of OMW as a relevant alternative source for organic substrates.

Use of Olive-Mill Wastewater for the Containment of Phelipanche ramosa in Open Field of Processing Tomato Crop

Phelipanche ramosa (L.) Pomel is a root holoparasitic weed that infested many crops, particularly the processing tomato. In semi-arid regions of the world, this problem is increasing, both in intensity and in acreages. In the last few years, researches for the control of this parasite has increased its effort to use suitable methods, as well as the utilization of natural compounds. In this regard, four experimental trials were carried out over three growing seasons (2014, 2016 and 2017), at Foggia (Apulia Region, Southern Italy), in the open field, on processing tomato (cv. “Dres”) crop, infested by P. ramosa, where the olive-mill wastewater (OMW) was incorporated into the soil at the dose of 80 m3 ha-1 40 days prior to tomato seedling transplant in comparison with the untreated control. The numbers of P. ramosa emerged shoots (branched plants) were significantly lower in the OMW treatment than in the untreated control. The tomato marketable yield showed a significantly higher value in the OMW treatment than the untreated control. No significant differences for the fruit qualitative characteristics were observed.

Combined treatment of olive mill wastewater by multi-soil-layering ecotechnology and adsorption on activated carbon/lime

Combined treatment of olive mill wastewater by multi-soil-layering ecotechnology and adsorption on activated carbon/lime

Olive oil extraction industry wastewater treatment by coagulation and Fenton’s process

The treatment of olive mill wastewater is a problem that still does not have an effective solution. In order to minimize this problem, there has been an improvement in the olive oil production process, moving from three-phase processes in oil mills to two-phase processes, and integrating the later with the oil extraction industry with n-hexane. This improvement does not totally solve the olive mill wastewater problem on its own, it only releases the olive mills from the environmental burden and concentrates the problem in the oil extraction industry. In this study it was proposed a treatment of a real effluent from an olive oil extraction industry, using the Fenton’s process integrated with coagulation. Different coagulant loads were studied to achieve the best conditions for this process. For the Fenton’s process, the loads of iron and hydrogen peroxide were optimized. The main evaluation parameters present in this study were chemical oxygen demand (COD), biodegradability and toxicity. Regarding the toxicity of the treated effluent, tests were performed on Aliivibrio fischeri.The studied effluent has a dark color, with an organic load of about 50 g L−1 of COD and high toxicity, with 9% of biodegradability. Coagulation process was studied with a single addition of coagulant (80 mg L−1) leading to 12.5 % ​​COD removal, while the combination of 20 mg L−1 plus 20 mg L−1 allows a COD reduction of 15 %. With the best conditions for coagulation (double phased addition of a total of 40 g L−1 of coagulant) integrated with the Fenton reaction (4 g L−1 of hydrogen peroxide, 2 g L−1 of iron (II) at pH 3 with 60 min of reaction) was possible to achieve about 45 % of COD removal. This allowed to increase the biodegradability, to a ratio higher than 40 %, for further biological treatment application to definitively treat the effluent.

Isolation, identification and optimization of enhanced production of laccase from Galactomyces geotrichum under solid-state fermentation

Laccases are a group of oxidases that catalyze the oxidation of a wide range of electron rich substrates like phenolic compounds, lignin and aromatic amines. They are of interest because of their potential to be used in environmental and industrial applications. In this research, potent laccase producer fungi were screened and isolated from olive mill wastewater (OMW). One of the 23 isolated fungi was identified as Galactomyces geotrichum based on 18S rDNA sequence analysis that detected good laccase activity. Produced laccase had a molecular weight of 55 kDa that was confirmed by zymogram analysis. This is the first report about the optimization of laccase Production by G. geotrichum under solid-state fermentation. The optimization was made by the Taguchi design of experiments (DOE) methodology. An orthogonal array (L25) was designed using Minitab 19 software to study four effective process factors in five levels for laccase production. The optimum condition derived was; moisture content (80%), fermentation time (14 day), CuSO4⋅5H2O as the inducer (300 μM), glucose as a co-substrate (5 g/L). Maximum laccase activity of 52.86 (U/g of dry substrate) was obtained using optimum fermentation condition. This study aimed to better understand the laccase producing microorganisms in OMW and take them to OMW treatment that is rich in phenolic compounds.

Olive Mill Wastewater Treatment: A Recent Review

Olive oil-producing countries in the Mediterranean region generate a considerable amount of olive mill wastewater (OMW), contributing to a severe environmental polluting issue due to its high pollution load. This effluent is exceptionally toxic to the whole soil-air-water ecosystem, and the living organisms inhabiting it (i.e., plants, animals, aquatic organisms, microorganisms, etc.). Many researchers have assessed the efficiencies of different treatment techniques to find an environmentally friendly and economically viable solution to be generally adopted. In light of that, the present review article summarizes the state-of-the-art concerning the OMW treatment options, with their pros and cons when possible

Treatment of Olive Mill Wastewater through Integrated Pressure-Driven Membrane Processes.

The disposal of wastewater resulting from olive oil production (olive mill wastewater, OMW) is a major issue for olive oil producers. This wastewater is among the most polluting due to the very high concentration of organic substances and the presence of hardly degradable phenolic compounds. The systems proposed for OMW treatment are essentially based either on conventional chemical-physical, biological and thermal processes, or on membrane processes. With respect to conventional methods, membrane processes allow to separate different species without the use of chemicals or heat. This work deals with the use of the integrated pressure-driven membrane processes for the treatment of OMW. They consist of a first stage (microfiltration, MF) in which a porous multichannel ceramic membrane retains suspended materials and produces a clarified permeate for a second stage (reverse osmosis, RO), in order to separate (and concentrate) dissolved substances from water. Laboratory scale experiments with different small flat sheet RO membranes were first carried out in order to select the most appropriate one for the successive bench scale tests with a spiral wound module having a large membrane surface. The aim of this test was to concentrate the dissolved substances and to produce water with low salinity, chemical oxygen demand (COD), and reduced phytotoxicity due to a low content of phenolic compounds. The trend of the permeate flux and membrane retention as a function of the volume concentration ratio was investigated. The influence of OMW origin and its aging on the membrane performance was also studied.

Olive mill wastewater treatment and valorization by extraction/concentration of hydroxytyrosol and other natural phenols

Olive mill wastewater (OMW) is a by-product generated from olive oil extraction systems. It contains high concentrations of organic compounds mainly phenols which cause environmental problems for the ecosystem, such as soil contamination and water pollution. Therefore, treatment of OMW is very much needed. Some of the naturally present chemicals in OMW have a positive economic value. In this investigation, liquid/liquid extraction using ethyl acetate (EA) as a solvent to recover such valuable compounds was investigated. Several parameters were studied namely, time of extraction, pH, EA/OMW volumetric ratio, and initial concentration of total phenols. Based on UHPLC analysis, hydroxytyrosol (HT) was the most abundant phenol in EA extracts from OMW. Many other phenols (tyrosol, oleuropein, p-coumaric acid, syringic acid, and 4-hydroxybinzoic acid) were also identified. Percentage recovery of HT reached 62 % after 2 h of extraction, at an EA/OMW ratio of 2/1 (v/v) and a pH of 2. Distribution coefficient of HT in EA was evaluated and was found to be around 0.8. The above process is envisioned to ultimately produce clean water which may be used in irrigation or in olive mills in a sustainable way. In addition, the extract is expected to have a high economic value.

Investigation of Olive Mill Wastewater Treatment with Advanced Oxidation Processes

Bu çalışmada, Balıkesir ilinde faaliyet gösteren bir zeytinyağı üretim tesisinden temin edilen zeytin karasuyunun arıtımında ozon (O3), ozon+hidrojen peroksit (O3+H2O2) ve fenton (Fe2++H2O2) proseslerinin etkinlikleri incelenmiştir. İlk olarak %10 kapasite ile O3 jeneratörü çalıştırılmış ve 3 farklı pH (4.75, 10 ve 11) değerinde 6 saat boyunca ozonlama işlemi gerçekleştirilmiş ve maksimum giderim verimi pH değeri 11 olarak ayarlandığında %15.27 olarak hesaplanmıştır. İkinci olarak %10 kapasite ile O3 jeneratörü çalıştırılmış ve ortama 500 mg L-1 H2O2 ilave edilmiştir. 6 saatlik bu deneme sonrasında giderim verimi %9.8 olarak gerçekleşmiştir. Son olarak zeytin karasuyunun arıtımı için farklı Fe2+ (2.014 g L-1 ve 4.028 g L-1) ve H2O2 (19.05, 44.44 ve 80 g L-1) konsantrasyonlarının etkilerinin incelendiği fenton prosesinde Fe2+ ve H2O2 konsantrasyonları arttığında deney sonunda ortamda kalan KOİ konsantrasyonları sürekli azalmıştır. Fe2+ konsantrasyonu 4.029 mg L-1 ve H2O2 konsantrasyonu 80 mg L-1 olarak ayarlanmış ve %81.94 oranında KOİ giderimi sağlanmıştır. Elde edilen sonuçlar fenton prosesinin, diğer proseslerden çok daha fazla etkinliğinin olduğunu ortaya çıkarmıştır.

Photovoltaic electrocoagulation treatment of olive mill wastewater using an external-loop airlift reactor

Over the years, olive mill wastewater (OMW), which is generated from olive oil production has attracted considerable attention as one of the most polluted wastewaters due to its high concentrations of toxic compounds. It is a truism nowadays to guide research towards a novel and efficient technologies in order to treat this hazardous waste.In this paper, detoxification of OMW in an external loop airlift reactor (ALR) by electrocoagulation (EC) powered by photovoltaic solar system as a renewable and sustainable energy source was investigated. The effects of the operating parameters, such as electrolysis time, initial pH, current density (CD), and the axial position of the electrode were studied in continuous flow with two aluminum electrodes. A rate of abatement of about 79.24% for COD, 94.82% for polyphenols and 97.87% for dark color was observed within 40 min of treatment at 32.14 mA/cm2 current density, a position of the electrodes at 35 cm from the bottom of the riser compartment, and initial pH of 5.6. Furthermore, under these optimal conditions, the power supplied by photovoltaic cells led to amount of electrode dissolved (ELC) and specific energy consumption (SEC) of around 0.1118 kg/m3 and 9.86 kWh/m3, respectively. It has been proven that the EC treatment of OMW in ALR coupled with renewable energy source offers a low operation cost (0.2 USD/m3) compared to other treatment processes.