Raw Olive Mill Wastewater Research Articles

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.

Land spreading of olive mill wastewater (OMW): Biodegradation of organic matter and polyphenols in soil and effect on the activity of the total soil microflora

Abstract Agricultural spreading of olive mill wastewater (OMW) can represent a promising alternative solution, provided that the operation is controlled and the doses applied are respected. However, a reserve toward OMW spreading remains, for fears of possible microbiological negative incidences on the soil. To contribute to assessing this area, we have tried to study their microbiological impact and the fate of OMW polyphenols in soil in a greenhouse. In comparison with untreated soil with OMW (control), the application of 50, 100, and 200 m3/ha was studied for two months. The results obtained revealed that phenolic extracts from raw OMW showed five major peaks by HPLC at 280 nm, which were present only in trace amounts after 2 weeks of treatment at neutral pH. The phenols and organic matter (OM) from OMW were biodegraded or reorganized, and the bacterial population of soil treated with 50 and 100 m3/ha OMW was significantly higher compared to the soil that received water. However, a dose of 200 m3/ha did not affect soil microflora. Consequently, using OMW by direct spreading can be recommended at doses of 50 and 100 m3/ha. Doses higher than those studied, which are considered excessive and not recommended, could have undesirable repercussions.

Characterizing and optimizing adsorption for olive mill wastewater processing in Loukkos, Morocco.

The present research consists of studying the characterization and treatment of the olive mill wastewater (OMWW) resulting from the olive industries of the region of Loukkos, Morocco. According to the national plan for green Morocco, the annual volumes of OMWW discharges increase with the expansion of the areas of olive plantations compared to agricultural activities. The study of the organic, mineral, and microbiological composition of the obtained OMWW showed that they are rich in microbiological (FMAT, Let M., and B.L.), mineral (total Kjeldhal nitrogen, orthophosphate, total phosphorus, sodium, potassium, calcium, copper, iron, zinc, manganese, and lead ions), and organic (COD, BOD5, and polyphenols) micropollutants with very high percentages that are higher than the standards in force. The treatment used in this study is the combined process of aerated lagooning/adsorption using powdered activated carbon after optimization of the experimental parameters (mass concentration of activated carbon (AC) and agitation rapidity (Ar)) by experiment design method. The obtained physicochemical parameters, such as pH, total suspended solids (TSS), chemical oxygen demand (COD), rate of discoloration, and polyphenol content of raw OMWW, were 4.87, 0.63, 80.3, 0.8, and 1.45 g/l, respectively. The results of these parameters for the treated OMWW were obtained in the order of 6.10, 0.22, 28, 0.28, and 0.44 g/l for pH, TSS, COD, discoloration rate, and polyphenol content, respectively. These results show that the proposed treatment significantly reduced acidity, TSS, COD, discoloration rate, and polyphenol contents, with a performance of about 25.26, 65, 65.13, 65, and 69.65%, respectively. This indicates that there is significant performance in the processing of exploited OMWW.

Effects Sequential Usage of Coagulations (Ferric Chloride or Alum) and Fenton's Solution or Biochar on Removal Phenolic Compounds and Organic Load from Olive Mill Wastewater

The chemical properties of the wastewater of 17 olive mills in the area between Al-Dafniyah into Qaraboli in the west of Libya were studied and chemical coagulants such as alum, ferric chloride, chemical oxidation, and biochar were used to remove the organic load and phenolic compounds from this water. The results showed that the wastewater of the olive mill is highly acidic with an average pH of 5.15 and its high content of solids reached 192 g/L, while the average of dissolved solids was 63.5 g/L and the organic solids were about 90% of the total solids and the average of chemical oxygen demand is 104.9 g O2/L, and the concentration of phenolic compounds is high and it was 1.86 g /L. In addition, the results showed that the usage of Ferric chloride as a coagulant gave higher removal percentage of phenolic compounds, dissolved solids, and chemical oxygen demand in comparison with Alum in the pH range of 6-9. The removal percentage was higher in alkaline pH, especially for phenolic compounds. Moreover, increasing the amount of the coagulant from 2 to 16 g/L enhanced the removal of phenolic compounds and chemical oxygen demand, while the removal efficiency of dissolved solids was weak, which required the use of chemical oxidation and adsorption on biochar to improve the efficiency of the removal. Although sequential treatments by coagulants and chemical oxidation by Fenton solution or biochar improved the percentage of removal in biochar treatments compared to chemical oxidation, the concentration of pollutants is still high for disposal, especially phenolic compounds. As a result of that, these methods need more studies to improve them. Langmuir and Freundlich’s models gave a good describing the adsorption of phenolic compounds on the surface of biochar. However, the adsorption capacity is low compared to the scientific literature, because this study uses raw olive mill wastewater with a high organic load, which causes competition between these substances on the adsorption sites or inhibits adsorption by depositing them on the surface of the biochar.

Assessment of the impact of diluted and pretreated olive mill wastewater on the treatment efficiency by infiltration-percolation using natural bio-adsorbents.

The current study was carried out to treat the olive mill wastewater (OMW) via infiltration percolation process, using low-cost natural adsorbents that could improve the ability of the system to enhance the disposal rate of elimination of pollutant from the OMW. The experimental pilot was composed of three PVC(polyvinyl chloride)columns with 10cm in diameter and 110-cm height equipped with lateral air entries. Each column was filled with four layers of 10cm of a mixture of sand (70%), charcoal (20%) and sawdust (10%) respectively. These layers were alternated by four permeable layers of 10cm of Pouzzolane. To assess the effect of the pretreatment on the efficiency of the system, three types of OMW were used: raw OMW, diluted OMW with domestic wastewater at 1/1(v/v) ratio and OMW pretreated with lime. For the column feed with raw OMW, an average removal of total COD (41%), dissolved COD (54%), NH4-N (40.25%), NO3- (15.76%), total phosphorus (55.63%) and orthophosphate (50.84%) was recorded. The results showed that the column feed with diluted OMW with domestic wastewater was the most efficient one with a removal rate that reached 93.2% of total COD, 86.2% of dissolved COD, 92% of polyphenol, 92% of orthophosphate (OP), 97.2% of total phosphorus (TP) and 81% of NH4-N. The pretreatment of OMW with lime gave the lowest removal rate for all the parameters: total COD (34%), dissolved COD (50%), NH4-N (30%), NO3- (- 21%), total phosphorus (15.19%) and orthophosphate (9.04%). This study demonstrated that the dilution is a way to optimize the efficiency of the system of infiltration-percolation in treating the OMW.

Comparing the performance of UV/Acetylacetone and UV/O3 processes for treatment of olive mill wastewater

Background: Olive mill wastewater (OMW) is characterized by its high organic content and refractory compounds. The aim of this study was to evaluate and compare the efficiency of UV/O3 and UV/ acetylacetone (UV/AcAc) processes for treatment of pretreated OMW by coagulation/microfiltration (C&M) process. Methods: In this study, a laboratory-scale UV plug flow reactor with ancillary equipment was fabricated. The experimental factors including initial pH (5-9), O3 dosages (1.5-4.5 g/h), and AcAc concentrations (0.01-0.03 M) were measured. For both processes, a reaction time of 120 min was considered. The effect of these variables on removal of wastewater contaminants including BOD, COD, TSS, turbidity, phenol, oil, and grease were investigated. Results: Results showed that raw OMW has a high load of pollutants and very low biodegradability (BOD5 /COD=0.12). In UV/O3 process, the optimal conditions were obtained at pH 8 and ozone injection at 4 g/h. The combined C&M-UV/O3 process removed 78.75% COD, 46.66% BOD5 , 90.88% total phenol, 91.78% TSS, 99.14% oil and grease, and 98.38% turbidity, with promotion of BOD5 / COD from 0.12 to 0.33. In UV/AcAc process, the optimal conditions were achieved at pH 5 and AcAc concentration of 0.03 M. The combined C&M-UV/AcAc process removed 58.75% COD, 67.58% BOD5 , 38.03% total phenol, 83.50% TSS, 93.65% oil and grease, and 95.00% turbidity, with promotion of BOD5 / COD from 0.12 to 0.22. Conclusion: The results showed that the UV/O3 process is completely superior to the UV/AcAc process for removal of OMW contaminants, as well as promoting the biodegradability of OMW.

Multistage treatment for olive mill wastewater: Assessing legal compliance and operational costs

A treatment train for the remediation of a raw olive mill wastewater (OMW) was investigated, aiming to comply with the emission limit values (ELVs) for direct discharge into water bodies. The following stages were proposed: (i) pre-treatment (filtration and sedimentation), (ii) coagulation, (iii) biological oxidation, and (iv) advanced oxidation process (AOP). Under the best-operating conditions for coagulation (0.8 g L−1 of Al2(SO4)3, pH = 4.5), high removal of total suspended solids (TSS) (97%), turbidity (98%), and phenols (57%) was achieved, along with a decrease in the inhibition of the biological activity. A subsequent biological oxidation stage provided a high removal of organic matter (chemical oxygen demand (COD) removal of 73%). For the third stage, three AOPs were applied and compared – photo-Fenton with UVA radiation (PF-UVA), anodic oxidation (AO), and ozonation (O3). After 3 h of treatment, the PF-UVA process (pH = 2.8, [H2O2] = 400–500 mg L−1, [Total dissolved iron]0 = 100 mg L−1) allowed to meet the ELV for COD, but the other parameters exceeded the threshold, while O3 process (inlet concentration = 100 mg O3 Ndm−3, gas flow = 0.2 Ndm3 min−1) allowed to comply with phenols, TSS, and sulfate limits. The AO process (current density up to 200 mA cm−2) was the least efficient AOP for all studied parameters. The operational costs for the coagulation and biological oxidation stages were estimated at 1.20 € m−3. Regarding the most effective AOPs, ozonation presented an estimated cost 2.3-fold higher than PF-UVA (11.9 € m−3vs. 5.2 € m−3).

Exploitation of olive mill wastewater in sorghum irrigation

Purpose In Morocco, the olive industry has made remarkable progress thanks to the "Green Morocco Plan" adopted by the Ministry of Agriculture. In 2018, the total production was around 2,000,000 tons of olives, with a growth of 11.93% compared to the previous years. However, each year this activity generates millions of tons of liquid and solid pollutants "olive mill wastewater (OMW)" and "pomace", discharged directly into water streams without prior treatment, which creates serious ecological problems. Method This study focuses on the use of raw and diluted OMW for the fertilization of sorghum. The OMW were characterized, diluted (½ and ¼), and applied at a rate of 5 L /week /m2. Sorghum growth was monitored by studying physiological performance (transpiration, stomatal conductance, the intensity of photosynthesis, and the performance of photosystem II). Results The raw OMW is acidic, salty, highly loaded with organic (COD / BOD5 = 7.1> 3), and inorganic matter and polyphenol content of 9 g/L. All the parameters for monitoring the growth of sorghum are lower for plants irrigated by raw OMW, which are symptoms of water stress. Using the T-test, the plants irrigated by half-diluted OMW have yielded the same results as those of the control. Conclusion Despite the fact that the half dilution of OMW has proved promising results, we suggest that it should be pretreated before its use in sorghum irrigation to reduce its organic loads and acidity.

Effective Approach of Activated Jordanian Bentonite by Sodium Ions for Total Phenolic Compounds Removal from Olive Mill Wastewater

Olive mill wastewater (OMW) is nowadays considered a serious environmental problem, especially within the Mediterranean region. With this in mind, water shortages are also a very serious and prevalent concern in third world countries. The aim of this study is to investigate the feasibility of using Jordanian bentonite, a simple and natural clay, as a possible adsorbent to decrease the negative characteristics of raw OMW, as an approach to the development of a methodology that addresses the OMW problem without affecting freshwater resources. The purified bentonite was activated by sodium ions at room temperature. FTIR, XRD, TGA, and BET surface area measurements were performed. OMW was contacted with both purified and activated bentonite in the batch technique to figure out the optimum parameters for the adsorption process. Physiochemical parameters of OMW were measured before and after treatment. The maximum adsorption qm was found as 8.81 mg/g at 323 K for the total phenolic compounds. The Langmuir and Freundlich models were utilized to describe the equilibrium isotherms and both models fit well. The parameters of thermodynamic show that the adsorption process was feasible, spontaneous, and endothermic in nature. These promising results along with the sodium activation of bentonite significantly improve bentonite’s adsorption capacity.

Nanocomposites Photocatalysis Application for the Purification of Phenols and Real Olive Mill Wastewater through a Sequential Process

In this study, a synthetic phenol solution of water and raw olive mill wastewater (OMW) were considered to achieve purification of the aqueous streams from pollutants. Only OMW was initially submitted to a coagulation/flocculation process, to reduce the turbidity, phenols, and chemical oxygen demand (COD). This first treatment appeared to be mandatory in order to remove solids from wastewater, allowing the successive use of laboratory-made core-shell nanocomposites. In detail, the optimal coagulant concentration, i.e., chitosan, was 500 mg/L, allowing a reduction of the turbidity and the COD value by 90% and 33%, respectively. After this, phenol wastewater was tested for photocatalysis and then OMW was treated by employing the laboratory-made nanocomposites in a photoreactor equipped with visible light sources and using optimal catalyst concentrations, which allowed for an additional 45% reduction of the COD of the OMW. In addition to this, the effect of the operating temperature was investigated on the photocatalytic process, and suitable kinetic models proposed.

Olive Mill Wastewater (OMW) Polyphenols Adsorption onto Polymeric Resins: Part I—Batch Anaerobic Digestion of OMW

Adsorption experiments using pure aqueous phenol solutions (in the range of 200 to 1000 ppm) were performed in the presence of different adsorbent resins (namely XAD 4, XAD 16, FPX 66) at 1% w/v (ratio of resin weight to phenol solution volume) at constant temperature (25 °C) and ionic strength (0.1 M NaCl). Langmuir and Freundlich isotherm models were used to describe the adsorption kinetics of all tested resins. The experimental equilibrium data were very well fitted to both Langmuir and Freundlich models (R2 > 0.900). FPX 66 exhibited the best efficiency among the tested resins. Regeneration of adsorbent resins thus recovery experiments of pure phenol solutions were also performed. Adsorbent tested resins were further examined in different mass ratios (10, 15, 20%) for phenolics removal from olive mill wastewater (OMW). A reduction of 75% of the soluble phenolic content was observed when 20% of FPX 66 was applied. Finally batch anaerobic digestion experiments of resin-pretreated OMW were carried out under mesophilic conditions (37 °C). Augmentation of methane production was measured during anaerobic digestion of resin-pretreated OMW compared to raw OMW. Polyphenols in OMW were proved to inhibit OMW fermentation and thus methane production.

Industrial scale bio-detoxification of raw olive mill wastewaters by the use of selected microbial yeast and bacterial strains to obtain a new source for fertigation

The Olive Mill Wastewaters (OMWs) are one of the most important agro-industrial wastes of the Mediterranean Countries and the disposal by draining them onto land has been proved to be damaging for soils, plants and groundwater due to their polluting power. The present report describes a new method for bio-detoxification of undiluted fresh OMW based on the driven selection of aerobic yeasts and bacteria. The identified yeast Candida boidinii A5y and the bacterium Paenibacillus albidus R32b strains allowed the treatment of freshly produced raw OMW characterized by very high COD value and phenolic content, when applied as sequential inoculum. The treated OMW showed the absence of antimicrobial effects and a strongly reduction of phytotoxic activity on the germination of several plant seeds. The process was successfully validated on an industrial scale without any pre-treatment, dilution and/or supplementation of the raw waste. Bio-detoxified OMW produced by this sustainable and low-cost process would be suitable for new non-chemical fertigation or soilless applications. The described procedure represents a virtuous example of circular economy efficaciously applied for a depleting agri-food resource.

Spreading raw olive mill wastewater is compatible with the growth and the beneficial functions of the earthworm Octodrilus complanatus

Recycling Olive Mill Wastewater (OMW) by its application on agricultural land is considered to be a sustainable practice for soil enrichment and waste management, and recent legislation permits large scale OMW recycling in Mediterranean countries. Therefore, studies on the effects of OMW application on earthworms under experimental conditions that closely resemble those occurring in the field are urgently required to facilitate the safe and ecologically friendly use of OMW at large scale. In this study, the effects of three-phase OMW liquid on the survival and growth of the earthworm Octodrilus complanatus (Dugès, 1828), commonly present in olive groves, were assessed. The liquid was applied at a rate i) equal to the maximum authorized by Greek legislation for olive groves fertilization (80 m3 ha−1) and ii) half of this amount (40 m3 ha−1). The effects were tested in an indoor experiment conducted in plastic containers. The results showed no adverse effect on the survival of the earthworms over a period of 56 days post-treatment, at both application doses. The growth of earthworms, as estimated by their body weight change at 28 or 56 days post-treatment, was not negatively affected; instead, there was a relative increase seen at the higher dose (80 m3 ha−1), although the difference between the treatments was not significant. Qualitative observations indicated feeding of earthworms on the OMW liquids. Organic matter decomposition was not affected and there was no significant alteration in the soil properties, except the electrical conductivity that was increased at the higher level of OMW application. Therefore, the application of OMW liquids at the doses recommended by the legislation does not affect the survival and growth of the earthworms and is compatible with their activities to promote organic matter decomposition.

A study of olive mill wastewaters obtained from different treatment processes effects on chemical and microbial properties of a Typic Xerofluvent soil and wheat yield

This study was carried out to investigate the potential for the usability of treated olive mill wastewater (OMW) as an organic amendment in agricultural soils under Mediterranean climate conditions. OMW was treated by two different treatment processes as economical (E-OMW) and advanced (A-OMW). The treated OMWs and raw OMW (R-OMW) were applied to a loamy soil at a rate of 100 m3 ha-1 year-1 for 2 years. Soils were sampled 15 days and about 5 months (at harvest) after OMW application for chemical and microbial analyses in each year. The total concentrations of N, P, Cu, Zn, and phenol of R-OMW decreased after both treatment processes while salinity (EC) and the total amounts of K, Na, and Ca increased. The applications of OMW caused changes in soil chemical (pH, EC, Pext, Kext) and microbial (microbial biomass-C (MB-C), microbial biomass-N (MB-N), basal soil respiration (BSR), N-mineralization (N-min)) characteristics (P < 0.05). In the second year of the experiment, initial samplings showed that the values of soil pH and EC increased significantly under all OMW applications compared to the control. High Pext concentrations were determined in soils amended with R-OMW, while there were high Kext concentrations in soils amended with the treated OMWs. The increases determined in MB-C and MB-N at all sampling times resulted in high MB-C/TOC and MB-N/TN ratios in soils amended with the treated OMWs. The wheat grain yield over the 2-year period showed that the application of the treated OMWs had a positive effect. It was determined that no negative effects occurred for either soil properties or wheat growth with the treated OMW applied at rates of up to 100 m3 ha-1. The addition of treated OMW after removal of its phenolic components may be considered as a good option for evaluating this waste in countries where OMW causes serious environmental pollution.

Olive mill wastewater treatment using infiltration percolation in column followed by aerobic biological treatment

This work aims to treat olive mill wastewater (OMWW) by infiltration percolation in different columns containing filtration sand, granular activated carbon, and lime, and thus followed by biological treatment using the soil microorganisms to the treatment that will give the best results. The optimum removal efficiency was obtained using granular activated carbon column mixed with 15% of lime with percentages removal of 39.33, 60.28, 53.17 and 88.74% for biological oxygen demand (BOD5), chemical oxygen demand (COD), polyphenols and suspended matter respectively. Aerobic treatment 30 days of OMWW obtained from the column of activated carbon mixed with 15% of lime, neutralized and diluted 15 times with distilled water was investigated. The results showed a significant percentage reduction of 79.78, 69.43, and 60.67%, respectively, for BOD5, COD, and polyphenols. The global removal percentages after the two successive treatments were 87.86% for COD, 87.39% for BOD5 and 81.59% for polyphenols compounds. Fourier Transformed Infrared spectroscopy analysis of crude OMWW, infiltrated percolated and biologically treated, showed a difference between the spectra that manifests by the reduction of the spectrum intensity bands after each treatment stage, which confirmed the analytical results. Soil microorganisms have shown their biodegradation efficiency of organic matter and polyphenols of these much-polluted effluents under aerobic conditions. The results indicated that the pretreatment of raw olive mill wastewater could be realized before biological treatment to obtain a satisfactory reduction.

Study of the phytotoxic potential of olive mill wastewaters on a leguminous plant 'Vicia faba L.'

We investigated the study of the phytotoxic potential of olive mill wastewaters (OMW) on the germination and growth responses of the faba bean 'Vicia faba L.' leguminous plant cultivated under an arid Mediterranean climate. The results showed that the raw OMW blocked the germination of the seeds tested, while OMW treated soil extracts stimulate the seeds' germination rate. The monitoring of the faba bean growth parameters in the different OMW treated soils showed that the optimal growth of the faba bean plants has been recorded for the soil amended with 25 m3 ha-1 of OMW. Although the 50 m3 ha-1 dose is the most suitable for the soil studied, our results showed that the 25 m3 ha-1 dose is the most suitable for the vegetative development, as well as for the productivity of the plant tested 'Vicia faba L.'.

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.

Toxicity evaluation of olive oil mill wastewater and its polar fraction using multiple whole-organism bioassays

Olive mill wastewater (OMW) as a by-product of olive oil extraction process has significant polluting properties mainly related to high organic load, increased COD/BOD ratio, high phenolic content and relatively acidic pH. Raw OMW from Slovenian Istria olive oil mill and its polar fraction were investigated in this study. Chemical characterization of OMW polar fraction identified tyrosol as the most abundant phenolic product, followed by catechol. Lethal and sub-lethal effects of OMW matrix and its polar fraction were tested using a battery of bioassays with model organisms: bacteria Vibrio fischeri, algae Chlorella vulgaris, water fleas Daphnia magna, zebrafish Danio rerio embryos, clover Trifolium repens and wheat Triticum aestivum. Raw OMW sample was the most toxic to V. fischeri (EC50 = 0.24% of OMW sample final concentration), followed by D. magna (EC50 = 1.43%), C. vulgaris (EC50 = 5.20%), D. rerio (EC50 = 7.05%), seeds T. repens (EC50 = 8.68%) and T. aestivum (EC50 = 11.58%). Similar toxicity trend was observed during exposure to OMW polar fraction, showing EC50 values 2.75–4.11 times lower comparing to raw OMW. Tested samples induced also sub-acute effects to clover and wheat (decreased roots, sprouts elongation); and to zebrafish embryos (increased mortality, higher abnormality rate, decreased hatching and pigmentation formation rate). A comprehensive approach using a battery of bioassays, like those used in this study should be applied during ecotoxicity monitoring of untreated and treated OMW.

Effects of raw and treated olive mill wastewater (OMW) by coagulation-flocculation, on the germination and the growth of three plant species (wheat, white beans, lettuce)

Olive mill wastewater (OMW) constitutes a grand environmental issue for olive oil producing countries. It produces a large amount of organic matter, which is difficult to degrade, in particular phenolic compounds which are responsible for the phytotoxic effect. The aim of this research is to determine the potential COD and phenolic compounds removal of OMW treated by coagulation-flocculation with lime as coagulant and to evaluate the effects of raw and treated OMW on the germination and the growth of three plant species (wheat ( Triticum turgidum L. var Durum ), lettuce ( Lactuca sativa varcrispa ) and White bean ( Phaseolus vulgaris L .). This treatment induced a high removal at a dose of 30g/L of lime by 40% and 97% respectively. The raw OMW showed an inhibitory effect on the germination and the growth of the three species. However, the three OMW dilutions (50%, 25% and 12.5%) stimulated the germination and the growth of wheat and white bean. The germination tests with OMW treated with lime and diluted at different concentrations present the best medium for growth of the three plants and the germination rate can reach 100%.

Agro-physiological and biochemical responses of Sorghum bicolor in soil amended by olive mill wastewater

Produced in huge quantities, olive mill wastewater (OMW) causes serious environmental problems in the Mediterranean basin, where olive growing is concentrated.The purpose of this study has been to evaluate the short term effects of various OMW quantities application on several Sorghum bicolor agro-physiological and biochemical parameters as well as the effects on the main properties of the amended soils. Four doses of OMW (25, 50, 75 and 100 m³ haˉ¹) have been applied in comparison to control soil not treated with OMW.Results have showed an improvement of the organic matter, total nitrogen and minerals contents in soils treated with OMW proportionally to the increase of the doses applied. Moreover, soils microbiological activities have been strongly enhanced in comparison with control soil. Furthermore, the study of the effects of OMW on the Sorghum bicolor seeds germination has showed that raw OMW has blocked germination seeds. However, various effects on Sorghum bicolor seeds germination have been observed for the OMW amended soils extracts related to quantities applied. An improvement of the main agro-physiological and biochemical parameters as stems height, stems thickness, leaves number, leaves circumferences’, roots lengths, plant productivity, proteins content and essential minerals elements rates for the plants growing in soil treated with 25 m3 ha−1 OMW dose has been reported. Nevertheless, clear inhibitions have been observed for the highest OMW doses applied as 75 and 100 m3 ha−1.