Detoxification Of Olive Mill Wastewater Research Articles

Effective Detoxification of Olive Mill Wastewater Using Multi-Step Surfactant-Based Treatment: Assessment of Environmental and Health Impact.

Olive mill wastewater (OMW) poses a significant environmental challenge and health concern in olive-producing countries, including Jordan. Surfactant micelles are frequently employed as solubilizing agents to enhance the water solubility of chemical compounds. This study aims to leverage the sodium dodecyl sulfate (SDS) micelles in a multi-step process to detoxify OMW for agricultural and industrial uses and reduce its impact. The OMW was treated in multiple steps: screening, coagulation with different chemicals, and distillation with different surfactants. The treatment steps were monitored using LC-MS, GC-MS, ICP-MS, chemical oxygen demand contents, and total phenolic compounds. The detoxification of OMW was evaluated using standard germination assays, MTT assays using tissue culture, and toxicity assays using fluorescence bacteria. Following the treatment, the seed growth rate improved significantly from 0% to 100%. The GC-MS revealed a substantial decrease in pollutants. The concentration of polyphenols was reduced to 2.5%, while the COD level decreased to 35%. The toxicity in bacteria was significantly reduced in a time-dependent manner, and the toxicity in human cells decreased by 95%. Additionally, between 50% and 95% of metals in OMW were removed. The multi-step SDS-based approach successfully detoxified the OMW and enhanced water quality, which would pave the road for its direct application in industry and agriculture.

Upgrading Major Waste Streams Derived from the Biodiesel Industry and Olive Mills via Microbial Bioprocessing with Non-Conventional Yarrowia lipolytica Strains

This study reports the development of a bioprocess involving the valorization of biodiesel-derived glycerol as the main carbon source for cell proliferation of Yarrowia lipolytica strains and production of metabolic compounds, i.e., citric acid (Cit), polyols, and other bio-metabolites, the substitution of process tap water with olive mill wastewater (OMW) in batch fermentations, and partial detoxification of OMW (up to 31.1% decolorization). Increasing initial phenolics (Phen) of OMW-glycerol blends led to substantial Cit secretion. Maximum Cit values, varying between 64.1–65.1 g/L, combined with high yield (YCit/S = 0.682–0.690 g Cit/g carbon sources) and productivity (0.335–0.344 g/L/h) were achieved in the presence of Phen = 3 g/L. The notable accumulation of endopolysaccharides (EPs) on the produced biomass was determined when Y. lipolytica LMBF Y-46 (51.9%) and ACA-YC 5033 (61.5%) were cultivated on glycerol-based media. Blending with various amounts of OMW negatively affected EPs and polyols biosynthesis. The ratio of mannitol:arabitol:erythritol was significantly affected (p < 0.05) by the fermentation media. Erythritol was the major polyol in the absence of OMW (53.5–62.32%), while blends of OMW-glycerol (with Phen = 1–3 g/L) promoted mannitol production (54.5–76.6%). Nitrogen-limited conditions did not favor the production of cellular lipids (up to 16.6%). This study addressed sustainable management and resource efficiency enabling the bioconversion of high-organic-load and toxic waste streams into valuable products within a circular bioeconomy approach.

Detoxification of olive mill wastewater by adsorption on activated clay

Detoxification of olive mill wastewater by adsorption on activated clay

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.

Potential of Acclimated Earthworm (Eisenia Andrei) for Detoxification of Olive Mill Wastewater

Potential of Acclimated Earthworm (Eisenia Andrei) for Detoxification of Olive Mill Wastewater

Advanced oxidation technologies for the treatment and detoxification of olive mill wastewater: a general review

Abstract Olive oil production has an economic importance for Mediterranean countries, ensuring employment opportunities and export earnings. The crushing units produce two types of residues, one solid (pomace) and the other liquid, called olive mill wastewater (OMW). This by-product has adverse effects on the olive oil sector and particularly on the quality of waters into which they are discharged. Hence, there is a critical need to orient the scientific research toward the treatment of this hazardous waste. Several techniques have been proposed and developed for OMW management. However, the advanced oxidation processes (AOP) remain the most advantageous with high treatment efficiencies. This trend allowed achieving a significant detoxification of OMW. A considerable amount of effort has been expanded to provide detailed and critical reviews on the use of this alternative technology in the treatment of water and wastewaters. Regrettably most, if not all, of these review papers were not focused mainly on OMW application. This paper aims to highlight the ancient and recent progress of various types of oxidation techniques for OMW treatment. Moreover, principles, advantages, limitations, and efficiencies of each method are presented, to gain a more scientific understanding of the most feasible approach regarding the treatment of this harmful residue.

Detoxification of Olive Mill Wastewaters by Fenton’s Process

Olive mill wastewaters (OMW) constitute an environmental problem affecting mainly Mediterranean Sea area countries where the olive mill industry is a very important economic sector. The strong impact and management issues of these effluents are mainly due to their seasonality, localized production, and high organic load with high toxic features and low biodegradability. As the olive oil industry is highly water demanding, the search for suitable water recovery strategies requires the development and optimization of advanced treatment technologies. The classical Fenton’s process is an interesting alternative, as it operates at room conditions of pressure and temperature. However, it shows some drawbacks, such as the generation of iron sludges, which require further management. Nevertheless, because of its features that make it industrially desirable, overcoming these limitations has been the focus of researchers in the last years. Bearing this in mind, this paper focuses on the recent research regarding OMW treatment using Fenton’s process. The use of Fenton’s peroxidation treatment at homogenous, heterogeneous, and photo-aided conditions is analysed. The use of solid catalysts may be an interesting way to avoid sludge formation. Light-driven Fenton can also reduce the amount of iron needed for effective degradation. Moreover, Fenton’s process integration in combined treatment schemes is discussed. Finally, remarks regarding its application at full scale are given.

Detoxification and methane production kinetics from three‐phase olive mill wastewater using Fenton's reagent followed by anaerobic digestion

AbstractBACKGROUNDThe implementation of an integrated treatment scheme consisting of an oxidation and an anaerobic digestion (AD) process was investigated at laboratory scale for the detoxification of olive mill wastewaters (OMWW) and their utilization for energy production. Initially, a detoxification step was implemented for oxidizing the OMWW in a batch‐stirred reactor with Fenton's reagent. Subsequently, the pretreated OMWW was fed to an anaerobic digester containing active sludge in order to determine its suitability for further biological treatment and biogas production.RESULTSThe kinetics of the two processes were examined for different initial conditions by varying the most important parameters: the initial concentrations of H2O2 and FeSO4.7H2O and the temperature of the oxidation process while the initial pH was kept constant. Increasing the initial concentrations of H2O2 and FeSO4.7H2O from 1 to 5 g L−1 and temperature from 20 to 35 °C, led to increased total phenolic content (TPC) removal (88.8%) and TOC degradation (35.4%) in the chemical oxidation process and an increased pseudo‐first‐order constant value (kAD = 0.718 d−1) in the AD process. The optimum kAD value corresponded to a biomethane production of 20.1 L CH4 / L pretreated OMWW. A modified pseudo‐first order model was selected to describe the conducted experiments.CONCLUSIONThe combination of Fenton's oxidation together with AD is an effective method for treating three‐phase OMWW as the TPC is first significantly decreased and then substrate biodegradability is enhanced as the proposed pretreatment methodology increases considerably the rate of AD. © 2018 Society of Chemical Industry

Bioenergetic strategy of microalgae for the biodegradation of tyrosol and hydroxytyrosol.

Olive mill wastewater has significant polluting properties due to its high phenolic content [mainly tyrosol (trs) and hydroxytyrosol (htrs)]. Growth kinetics and a series of fluorescence induction measurements for Scenedesmus obliquus cultures showed that microalgae can be tolerant of these phenolic compounds. Changes in the cellular energy reserves and concentration of the phenolic compounds adjust the "toxicity" of these compounds to the microalgae and are, therefore, the main parameters that affect biodegradation. Autotrophic growth conditions of microalgae and high concentrations of trs or htrs induce higher biodegradation compared with mixotrophic conditions and lower phenolic concentrations. When microalgae face trs and htrs simultaneously, biodegradation begins from htrs, the more energetically demanding compound. All these lead to the conviction that microalgae have a "rational" management of cellular energy balance. Low toxicity levels lead to higher growth and lower biodegradation, whereas higher toxicity levels lead to lower growth and higher biodegradation. The selection of appropriate conditions (compatible to the bioenergetic strategies of microalgae) seems to be the key for a successful biodegradation of a series of toxic compounds, thus paving the way for future biotechnological applications for solving complicated pollution problems, like the detoxification of olive mill wastewater.

Detoxification of Olive Mill Wastewater and Bioconversion of Olive Crop Residues into High-Value-Added Biomass by the Choice Edible Mushroom Hericium erinaceus.

Environmentally acceptable disposal of olive cultivation residues (e.g., olive prunings; olive pruning residues (OLPR)) and olive mill wastes is of paramount importance since they are generated in huge quantities within a short time. Moreover, olive mill wastewater (OMW) or sludge-like effluents ("alperujo"; two-phase olive mill waste (TPOMW)) are highly biotoxic. Hericium erinaceus is a white-rot fungus which produces choice edible mushrooms on substrates rich in lignocellulosics, and its suitability for the treatment of olive by-products was examined for the first time. Fungal growth resulted in a notable reduction of OMW's pollution parameters (i.e., 65% decolorization, 47% total phenolic reduction, and 52% phytotoxicity decrease) and correlated with laccase and manganese peroxidase activities. Solid-state fermentation of various mixtures of OLPR, TPOMW, and beech sawdust (control) by H. erinaceus qualified OLPR in subsequent cultivation experiments, where it exhibited high mushroom yields and biological efficiency (31%). Analyses of proximate composition and bioactive compound content revealed that mushrooms deriving from OLPR substrates showed significantly higher crude fat, total glucan, β-glucan, total phenolics, and ferric-reducing antioxidant potential values than the control. H. erinaceus demonstrated the potential to detoxify OMW and bioconvert OLPR into high-quality biomass, and hence, this fungus could be successfully exploited for the treatment of such by-products.

Land Application-Based Olive Mill Wastewater Μanagement

Land application of olive mill wastewater (OMW) is considered a promising low-cost practice for olive-oil producing countries. The objectives of this work were to investigate: (i) OMW treatment potential of a land treatment system (LTS), planted with a E. camaldulensis species, regarding N, P, C, and phenols; (ii) the effects of OMW on chemical properties of soil and soil solution characteristics; and (iii) the performance of E. camaldulensis in terms of biomass production and N and P recovery. E. camaldulensis received OMW for two growing seasons at rates based on maximum organic loading. These rates were almost equivalent to the reference evapotranspiration of the area. Soil solution and soil samples were collected from three different depths (15, 30 and 60 cm) at specified time intervals. -Also, samples of plant tissues were collected at the end of application periods. OMW land application resulted in significant reduction in inorganic and organic constituents of OMW. At 15 cm of soil profile, the average removal of COD, TKN, NH4+-N, TP, In-P, and total phenols approached 93%, 86%, 70%, 86%, 82%, and 85%, respectively, while an increase in soil depth (30 and 60 cm) did not improve significantly treatment efficiency. Furthermore, OMW increased soil organic matter (SOM), total kjeldahl nitrogen (TKN), and available P, particularly in the upper soil layer. In contrast, low inorganic N content was observed in the soil throughout the study period caused probably by increased competition among soil microorganisms induced by the organic substrate supply and high C/N ratio. Also, electrical conductivity (EC) and SAR increased by OMW addition, but at levels that may do not pose severe risk for soil texture. Enhancement of soil fertility due to OMW application sustained eucalyptus trees and provided remarkable biomass yield. In conclusion, land application of OMW has a great potential for organic matter and phenol assimilation and can be effectively used for OMW detoxification.

Dephenolization, dearomatization and detoxification of olive mill wastewater with sonication combined with additives and radical scavengers

In this study, the effects of some additives [manganese (III) oxide (Mn3O4), Cu+2, Fe0 and potassium iodate (KIO3)] and some radical scavengers [sodium carbonate (Na2CO3), perfluorohexane (C6F14) and t-butyl alcohol (C4H10O)] on the sonication of olive mill effluent wastewater (OMW) were investigated since the wastewaters of this industry are removed with low efficiencies. The maximum total phenol and total aromatic amines (TAAs) removal efficiencies were 88% and 79%, respectively, at 60°C with only 150min sonication. The maximum phenol removal was found as 98% with 19mgL−1 perfluorohexane and 5mgL−1 Fe0 while the maximum TAAs removal was 99% with 16mgL−1 KIO3. Catechol, tyrosol, quercetin, caffeic acid, 4-methyl catechol, 2-phenylphenol (2-PHE) and 3-phenyl phenol (3-PHE) were detected as phenol intermediates while trimethlyaniline, aniline, o-toluidine, o-anisidine, dimethylaniline, ethylbenzene and durene were identified as TAAs in the OMW. The maximum acute toxicity removals were 96% and 99% in Vibrio fischeri and Daphnia magna, respectively. Total phenol, TAAs and the toxicity in an OMW were removed efficiently and cost-effectively through sonication.

Improvement of biological process using biocoagulation–flocculation pretreatment aid in olive mill wastewater detoxification

Olive mill wastewaters (OMWW) are a significant source of potential or existing environmental pollution in the Mediterranean countries. Treatment and reuse of OMWW present significant challenges, both due to the nature of olive oil production (seasonal and concentration in a small scale) and due to the characteristics of the wastewater (high chemical oxygen demand (COD) and high phenolic content). In the present work, experiments of different pretreatment methods were undertaken and compared in order to select the most adequate process to be applied before biological treatment of OMWW. In fact, three different pretreatments were tested and compared: two different coagulants (alginate and Kim2120) and electrocoagulation (EC) process. At the second stage, biological treatment (using white-rot fungus) was investigated. Tests were conducted with raw OMWW and with OMWW diluted in 50% tap water and adjusted to a neutral pH with lime. The raw effluent presents high COD (178 g O2 l−1), about 6.4g l−1 of total suspended solids (TSS), a high conductivity (29 mS cm−1), acidic pH 4.8, and turbidity of 90 NTU. Results show that after 90 min of EC process, using 15 V/m2 voltage, a maximum of 49% of organic matter removals was achieved. The optimum removals of COD and turbidity obtained were 39 and 75%, respectively when 20 mg l−1 dose of alginate is used, especially at pH 7. Coagulation using Kim2120 at 10 mg l−1 applied on diluted OMWW showed reduction reaching 52.3% of COD and 85% of turbidity. The maximum removal of total polyphenols, tyrosol and hydroxytyrosol obtained were 60.1, 23.1, and 59.1% with lime/alginate and 64.2, 67.8, and 76.3% with lime/kim2120, respectively. Only 57% of polyphenols was removed by EC. The pretreated effluents by different physicochemical processes tested showed that the best yields were obtained with lime/kim2120. The pretreated olive mill wastewater was then treated aerobically with white-rot fungus. The results showed that the white-rot fungus was capable of reducing 68% and 75% of COD, respectively for the diluted OMWW and pretreated by lime or lime/Kim2120, after only 5 days of growth. The best biological treatment was obtained with neutral pH.

The effects of olives harvest period and production year on olive mill wastewater properties – Evaluation of Pleurotus strains as bioindicators of the effluent’s toxicity

Olive mill wastewater (OMW) generated during the oil extraction from Olea europea L. var. koroneiki olives was sampled at the beginning, the middle and the end of the harvesting season for three successive crop production years, and from four olive mills. OMW samples were examined in respect to their physicochemical characteristics, fatty acid composition of the lipid fraction, and adverse effects on biomass production of nine white-rot fungi of the basidiomycetous genus Pleurotus. Total N, nitrogen species, potassium and phosphate concentrations as well as total phenolics content of OMW samples were influenced by the crop year but not from the harvest period (albeit higher values for nitrate, nitrite, phosphate and potassium as well as total phenolics contents were obtained during ripening of olives), whereas protein concentration, total organic carbon and total solids were not significantly affected by the crop year or the harvest period. In addition, fatty acids composition, i.e. nC14:0, nC16:1Δ9cis, nC17:1Δ10cis, nC18:0, nC18:1Δ9cis, nC22:0 and nC24:0 varied significantly during different crop years and harvest periods. Olive fruits maturity and biannual alternate-bearing appear to play key-roles in the fatty acid variation detected in OMW samples. OMW toxicity as evaluated by the mycelium growth of Pleurotus strains was influenced significantly by the phenolic content of OMW samples obtained during three successive crop years; in contrast, the olives harvest period did not affect Pleurotus biomass production. Hence, experimental data indicated that selected Pleurotus strains could serve as bioindicators of OMW toxicity. Development of viable OMW detoxification processes as well as the exploitation of the effluent’s fertilizing value are discussed in the light of the above findings.

Treatment of wastewaters from the olive mill industry by sonication

AbstractBACKGROUND: In this study, the effects of additives (manganese (III) oxide (Mn3O4), Cu+2, Fe0 and potassium iodate (KIO3)) and radical scavengers (sodium carbonate (Na2CO3), perfluorohexane (C6F14) and t‐buthyl alcohol (C4H10O)) on the dephenolization, decolorization, dearomatization and detoxification of olive mill wastewater (OMW) by sonication were investigated because wastewaters from this industry are not removed effectively.RESULTS: The maximum COD, color, total phenol and total aromatic amines (TAAs) removal efficiencies were 63, 82, 78 and 71%, respectively, at 60 °C with sonication only. The TAAs and phenol yields were increased to 96 and 97% with 6 mg L−1 KIO3 and 3 mg L−1 Fe0 while color removal reached 97% with 6 mg L−1 C6F14. The total annual cost with sonication only was 665 € m−3 year−1 while the cost slightly increased (666€ m3 year−1) with C6F14. The maximum acute toxicity removals were 97‐98% in Daphnia magna and Vibrio fischeri The Microtox acute toxicity test was more sensitive than the Daphnia magna to the OMW samples.CONCLUSION: COD, color, total phenol, TAAs and toxicity in an OMW were removed efficiently and cost‐effectively by sonication. © 2012 Society of Chemical Industry

Biodegradation and detoxification of olive mill wastewater by selected strains of the mushroom genera Ganoderma and Pleurotus

Thirty-nine white-rot fungi belonging to nine species of Agaricomycotina (Basidiomycota) were initially screened for their ability to decrease olive-mill wastewater (OMW) phenolics. Four strains of Ganoderma australe, Ganoderma carnosum, Pleurotus eryngii and Pleurotus ostreatus, were selected and further examined for key-aspects of the OMW biodegradation process. Fungal growth in OMW-containing batch cultures resulted in significant decolorization (by 40–46% and 60–65% for Ganoderma and Pleurotus spp. respectively) and reduction of phenolics (by 64–67% and 74–81% for Ganoderma and Pleurotus spp. respectively). COD decrease was less pronounced (12–29%). Cress-seeds germination increased by 30–40% when OMW was treated by Pleurotus strains. Toxicity expressed as inhibition of Aliivibrio fischeri luminescence was reduced in fungal-treated OMW samples by approximately 5–15times compared to the control. As regards the pertinent enzyme activities, laccase and Mn-independent peroxidase were detected for Ganoderma spp. during the entire incubation period. In contrast, Pleurotus spp. did not exhibit any enzyme activities at early growth stages; instead, high laccase (five times greater than those of Ganoderma spp.) and Mn peroxidases activities were determined at the end of treatment. OMW decolorization by Ganoderma strains was strongly correlated to the reduction of phenolics, whereas P. eryngii laccase activity was correlated with the effluent’s decolorization.

Detoxification of olive mill wastewaters by zinc–aluminium layered double hydroxides

Disposal of olive mill waste waters (OMWW) represents a serious problem due to its elevated toxicity and pollution risk for environmental and aquatic bodies, which is mainly related to its polyphenol content. The use of layered double hydroxides (LDHs) or anionic clays for OMWW detoxification may represent an effective remediation process. In the current study, OMWW was treated with cold methanol to obtain a dark humic acid-like precipitate made of high molecular weight organic compounds named polymerin and a supernatant made of low molecular weight organics named OMWW-S. After precipitation with methanol, phenol content decreased from 2.14 g L −1 to 0.80 and 1.20 g L −1, in polymerin and OMWW-S, respectively. The chemical oxygen demand of OMWW-S decreased by about 30% with respect to raw OMWW, from 62.2 to 40.2 g L −1. A phenolic concentrate, named OMWW-E was also obtained by ethyl acetate extraction of OMWW-S at pH 2.0. LDHs of zinc and aluminium (LDH) were obtained at room temperature and after calcination at 450 °C (LDH-450). An organo-mineral complex of LDH with polymerin (LDH-Pol) was also synthesised. Phenols from OMWW-E were sorbed preferentially on three matrices according to the following order: LDH-450 > LDH > LDH-Pol, with percent sorption of up to 73% for LDH-450. Repeated cycles of sorption of OMWW-S onto LDH-450 decreased phenol concentration by about 90%. Use of remediated water in a phytotoxicity bioassay revealed scant inhibition of germination and coleoptile elongation rate in tomato seeds and seedlings. Thus, OMWW-S after sorption onto LDH-450 could represent a low cost source of irrigation water for arid soil of the Mediterranean region.

Original and Residual Phytotoxicity of Olive Mill Wastewater Revealed by Fractionations before and after Incubation withPleurotus ostreatus

Concentrations of dissolved organic carbon (DOC) and total phenols (TP), and the phytotoxicity to cress (Lepidium sativum L.) were determined for three molecular-sized fractions of olive mill wastewater (OMW), <1000, 1000-5000, and >5000 Da, before and after incubation with Pleurotus ostreatus. The <1000-Da fraction contained 82% of the total DOC and 48% of the TP, and was the most phytotoxic. Ethyl acetate separation of aqueous and solvent fractions showed that the aqueous fraction contained 93% of the total DOC, 83% of the TP, and was most phytotoxic, indicating low importance of monomeric phenols. Incubation of whole OMW and of the separate size fractions with P. ostreatus mycelia reduced TP by factors of 4.3-5.3, but exerted diverse impact on phytotoxicity; overall, P. ostreatus efficacy in organic load removal and OMW detoxification was limited. Additional size fractionation of the incubated fractions revealed that most residual phytotoxicity was associated with low-molecular weight (MW) compounds originated from the <1000 Da fraction and not with low-MW byproducts from the degradation of higher-MW fractions and that polymerized metabolites were nonphytotoxic. Total phenols should not be used as sole indicators of the successful remediation of OMW.

Dephenolization and detoxification of olive-mill wastewater (OMW) by purified biotic and abiotic oxidative catalysts

The capability of two oxidative catalysts, a laccase from Rhus vernicifera and birnessite, a manganese oxide, in the dephenolization and detoxification of two olive-mill wastewater (OMW) samples, C1 and C2, differing for complexity and composition, was evaluated. OMW phenolic extracts (EC1 and EC2) and mono-substrate solutions of phenols mostly present in OMW samples were also tested. Birnessite was more effective than laccase in removing the phenolic content from mono-substrate solutions (more than 70% of each initial phenolic concentration) and of either OMW samples or EC1 and EC2 extracts. For instance, 60% of the total phenolic content of EC1 was removed after 48-h treatment with 5 mg mL −1 birnessite and the efficiency was lower as greater was the complexity of the OMW sample (only 17% removal from EC2 over the same time span). Phytotoxicity tests with Lepidium sativum and Lycopersicon esculentum seeds and antibacterial toxicity tests with Bacillus megaterium were performed on crude OMW samples and their extract and exhausted fractions before and after the catalytic treatment. Results demonstrated that (a) monomeric phenols were certainly but not exclusively responsible of OMW phytotoxicity, whereas their removal led to a quite complete elimination of the toxicity toward bacterial growth; (b) other components not removable by the oxidative catalysts very likely contribute to OMW phytotoxicity; and (c) the choice of the vegetal species to use in toxicity tests might be crucial for correct and easily interpretable results. Overall the results provided useful information on the possible use of oxidative catalysts for the efficient treatment of complex aqueous wastes such as those deriving from olive industry.

Characterisation of Paenibacillus jamilae strains that produce exopolysaccharide during growth on and detoxification of olive mill wastewaters

A total of 10 bacterial strains were isolated from a compost of corn treated with olive mill wastewaters (OMW) and selected by their capacity to synthesize exopolysaccharides (EPS). Morphological, physiological, biochemical and nutritional tests were used for a phenotypic study. A numerical analysis showed that all strains were 90% similar to each other. A DNA–DNA hybridization assay confirmed that all the strains belonged to Paenibacillus jamilae species. All the characterized strains were able to produce EPS growing on OMW batch cultures. The strain which was able to produce the highest EPS yield was chosen to perform an assay for testing its putative detoxifying activity, and it showed to reduce more than half the toxic capacity of the OMW. The results presented in this study, indicated the possible perspectives for using these bacterial strains to produce EPS and contribute to the bioremediation of the waste waters that are produced in the olive oil elaboration process.