Biodegradation Of Olive Mill Wastewater Research Articles

Biodegradation of olive mill wastewater by two bacterial strains

Wastewater from olive mill is a by-product of olive oil production, that is a serious environmental problem in many Mediterranean countries. The production of large quantities of waste in a short period of time together with the high organic load and high toxicity of the waste make it difficult to deal with the problem. Phenolic compounds are one of the main factors responsible for the toxicity of olive mill wastewater (OMW). In the present work, two selectively anaerobic bacteria, Sporolactobacillus spp. and Rhodopseudomonas spp. isolated from compost tea were used. These two strains were tested for their ability to reduce the BOD5 and COD levels and to degrade polyphenols responsible for the toxicity of OMW. The two strains were able to grow on a dilution of a natural OMW and largely degrade the polyphenols. The dilution depended on the initial COD value of the waste. After 90 days of treatment reduction over 70% was observed in all three parameters which were measured while in an additional sampling that carried out in the 150th day, the reduction of BOD5, COD and total phenols concentration, reached to 96.1%, 81.8% and 75.1% respectively. Additionally, an increase in the pH was observed, moving from acidic to slightly alkaline. All these features make the two strains attractive candidates for the development of a biotechnological process for the biodegradation of OMW.

Biodegradation of Olive Mill Wastewater by a newly isolated novel bacterial consortium under RSM optimized culture conditions

Olive Mill Wastewater (OMW) is the main olive processing residual product and its disposal represent a relevant environmental issue in Mediterranean countries, specialy in Tunisia where olive oil production is largely received in a revised form and concentrated in a short-lasting period. OMW is characterised not only by its high pollutant load, salinity and phytotoxic levels of polyphenols, but also by a high amount of organic compounds and plant mineral. Therefore, the optimization process was analyzed using custom response surface methodology (RSM) and central composite design (CCD). In the present study, the effect of different combinations of nine strains S1 (Aeromonas salmonicidae), S2 (Cryptococcus humicolus), S3 (Penicillium sp.), F1 (Aeromonas hydrophyla), F2 (Candida boidinii), F3 (Bacillus sp.), T1 (Sphingomonas paucimobilis), T2 (Staphylococcus xylosus) and T3 (Lactobacillus sp.) was studied using the equilateral triangle diagram and a mixture experimental design to assess color and COD removal during the species growth., Under optimal conditions, the developed bacterial consortium (59% (S, S2 and S3), 28.28% (F1, F2 and F3) and 12.62% (T1, T2 and T3)) was able to decolorize completely (>84%) the OMW within 4 days at static condition. The color and COD removal were 90% and 86%, respectively. A very high regression coefficient between the variables and the responses: color and COD removal were R2 = 84.78% and R2 = 80.44%, respectively indicating an excellent evaluation of experimental data by polynomial regression model. UV–vis spectroscopy analysis confirmed the biodegradability of OMW by the developed bacterial consortium.

Treatment of olive mill wastewater through employing sequencing batch reactor: performance and microbial diversity assessment.

This work describes the performance of a sequencing batch reactor (SBR) and the involvement of a novel reconstituted bacterial consortium in olive mill wastewater (OMW) treatment. The organic loading rate applied to the SBR was serially increased in terms of initial COD from 10to 75 gL-1 to allow gradual acclimatization of activated sludge to high concentrations of toxic compounds in OMW. After the acclimatization period, up to 60% of the total COD content were effectively biodegraded from OMW at 75gL-1 COD within 30day hydraulic retention time. The diversity and community composition of cultivable bacteria participating in the aerobic process of treating OMW were further assessed. A total of 91 bacterial strains were isolated from the reactor and analyzed by amplification of the 16S-23S rRNA internal transcribed spacer (ITS) region and by 16S rRNA gene sequencing. The most abundant phylum was Firmicutes (57.1%) followed by Proteobacteria (35.2%) and Actinobacteria (7.7%). The use of the Biolog® Phenotype Microarray system to evaluate the ability of isolated strains to utilize OMW phenolic compounds is reported in this work for the first time. Interestingly, results showed that all species tested were able to utilize phenolics as sole carbon and energy sources. The removals of COD and phenolics from undiluted OMW by the reconstituted bacterial consortium were almost similar to those obtained by the acclimatized activated sludge, which suggest that cultivable bacteria play the major role in OMW biodegradation. Phytotoxicity assays using tomato seeds showed a significant improvement of seed germination values for treated OMW. Our overall results suggest that the novel developed bacterial consortium could be considered as a good prospect for phenolics-rich wastewaters bioremediation applications.

The influence of phenols extracted from olive mill wastewater on the heterotrophic and mixotrophic growth of Scenedesmus sp.

ABSTRACTBACKGROUNDMixotrophic and heterotrophic growth of microalgae through biodegradation of olive mill wastewaters (OMW) is a promising strategy to improve the economic viability of microalgae production processes. However, OMW are characterized by an elevated phenols content, which makes their treatment by biological processes difficult.In this work, the influence of OMW phenols on microalgae growth was investigated by using the phenols extracted with a resin from OMW.RESULTSOMW phenols, at 0.5 g L−1, were found to inhibit the growth of Scenedesmus sp. This inhibition was reduced by replacing an inoculum in the stationary phase with an inoculum in the exponential phase. Even with this strategy, a relevant negative effect (− 30%) on maximum cell concentration was found, which could be prevented by decreasing the phenol concentration to 0.1 g L−1. Under mixotrophic conditions, phenols reduced light penetration, limiting photosynthetic activity without significant improvement in phenols biodegradation. Under both mixotrophic and heterotrophic condition, percentage phenols removal up to 57% was achieved.CONCLUSIONSThe most promising strategy to achieve integrated microalgal cell growth and OMW phenols biodegradation is the heterotrophic cultivation with phenols concentration not greater than 0.1 g L−1 and an inoculum in exponential phase. © 2018 Society of Chemical Industry

Integrated microalgae biomass production and olive mill wastewater biodegradation: Optimization of the wastewater supply strategy

Olive mill wastewater (OMW) was supplied to Scenedesmus sp. cultures to simultaneously achieve biomass production and wastewater biodegradation. Two OMW supply strategies were implemented to prevent the reduced growth performances that are attained, compared to photoautotrophic cultivation, when OMW is supplied at the beginning of cultivation (batch strategy). A fed-batch strategy including the gradual OMW supply yielded a biomass production equal to 0.86 g/L, while 1.4 g/L was attained by a two-stage strategy including OMW addition during nitrogen-starvation. OMW enhanced the carbohydrate accumulation (up to 44%) through the removal of OMW sugars (60–70%). About 55% OMW phenol removal was achieved by the fed-batch strategy when the phenol concentration was lower than 100 mg/L, and by the two-stage strategy when the heterotrophic stage lasted longer than 8–10 days. The illustrated results indicate that the OMW supply strategy can be purposefully tailored to regulate biomass production and OMW biodegradation.

Anaerobic biodegradation of olive mill wastewater: batch and UASB reactor performance

Batch biodegradability tests were carried out to determine the digestibility of olive mill waste water (OMW), the COD removal and potential methane (CH4) yield. The tests were prepared with anaerobic sludge and different volumes of OMW (0 ml, 10 ml unfiltered, 20 ml unfiltered and 10 ml of filtered sample). The biodegradability of the mixtures based on the gas production rate was 43, 58, 53, and 59%, respectively. Anaerobic treatment of OMW was also investigated in an up flow anaerobic sludge blanket (UASB) reactor at organic loading rates (OLRs) between 1.6 and 8 kg COD m−3 d−1 at a hydraulic retention time of 15 h. The results showed stable COD removal efficiencies (∼85%) for OLRs up to 7.6 kg m−3 d−1. Gradual improvement in the biogas production rate was observed with higher OLRs. The highest CH4 yield was about 0.37 L CH4 g−1 of COD removed.

Anaerobic biodegradation of olive mill wastewater: batch and UASB reactor performance

Batch biodegradability tests were carried out to determine the digestibility of olive mill waste water (OMW), the COD removal and potential methane (CH4) yield. The tests were prepared with anaerobic sludge and different volumes of OMW (0 ml, 10 ml unfiltered, 20 ml unfiltered and 10 ml of filtered sample). The biodegradability of the mixtures based on the gas production rate was 43, 58, 53, and 59%, respectively. Anaerobic treatment of OMW was also investigated in an up flow anaerobic sludge blanket (UASB) reactor at organic loading rates (OLRs) between 1.6 and 8 kg COD m−3 d−1 at a hydraulic retention time of 15 h. The results showed stable COD removal efficiencies (∼85%) for OLRs up to 7.6 kg m−3 d−1. Gradual improvement in the biogas production rate was observed with higher OLRs. The highest CH4 yield was about 0.37 L CH4 g−1 of COD removed.

A Novel Two-Step Process to Co-valorize Antioxidant Rich By-products of Olive and Grape Processing Industries

An integrated process for collective recovery of phenolic compounds from olive mill wastewater (OMW) and grape pomace (GP), which would also benefit easier biodegradation of OMW in a further process, was developed. Response surface methodology was employed to optimize the process parameters. Treatment of GP with OMW resulted in the transfer of 64.41 % of total polyphenols contained in OMW to GP under the optimal conditions predicted by the model. In the following step, extraction of phenolic compounds in treated-GP with ethyl alcohol:water under the optimum conditions predicted by the model was performed and 11.97 mg g−1 phenolics was recovered. The total antioxidant activity of the recovered phenolics was 81 % (inh.).

Agronomic application of olive mill wastewater: Effects on maize production and soil properties

This study investigates the effect of direct amendment of olive mill wastewater (OMW) on the fertility of soil, described as poor in the area of Marrakech (semi-arid region) in Morocco. The treated plots were amended with untreated OMW generated by a traditional extraction process at the amount of 10 L/m2/year during two consecutive years. Results of these two years treatments with crude OMW at relatively high dose reveal an important increase in soil physicochemical characteristics, namely electric conductivity (EC), Na+, K+, phosphorus, nitrogen, organic matter and soluble phenolic compounds. EC of treated soil was enhanced from 0.34 to 2.91 mS/cm as compared to the control soil. After spreading OMW in soil, the amounts of its nutritive elements increased by 81% for nitrogen, 66% for phosphorus and 88% for potassium. The accumulation of phenolic compounds and the increase of total peroxidase activity in plants provide evidence of their protective role against the physiological stress induced by OMW. However, this enrichment in mineral and nutritive elements decreased three months after OMW application, revealing OMW biodegradation in the studied calcareous soil. In parallel, an increase in the contents of the soluble phenolic compounds on the upper layer of soil was denoted and maize plants growth was efficiently raised. Significant amelioration was obtained notably in terms of fresh and dry weight of leaves, leaves area, spikes fresh and dry weight, 100 seeds weight and straw yield (37, 54, 27, 24, 14 and 9% respectively). Along with the correct choice of convenient soils notably calcareous ones and tolerant crops such as maize, this method could constitute an efficient approach for avoiding problems attributed to the uncontrolled disposal of these effluents and an effective strategy to regenerate degraded soils and represents an economical alternative that provides a local fertilizer.

Integrated biomass production and biodegradation of olive mill wastewater by cultivation of Scenedesmus sp.

Biomass production and bio-treatment of olive mill wastewater (OMW) were simultaneously achieved by cultivation of Scenedesmus sp. The influence of medium composition was addressed by analyzing the effect of the addition of unsterilized OMW (9% v·v−1) and of inorganic nutrients, and the use of tap water. Performance of implemented treatments was assessed by analysis of the following variables: biomass productivity, growth rate, content of target microalgal fractions (lipids and carbohydrates), and consumption of OMW organic carbon fractions (reducing sugars and phenols).The addition of unsterilized OMW (9% v·v−1) caused darkening of microalgal cultures inducing transition to heterotrophic growth. Growth rate values attained in heterotrophic cultures (with OMW) (0.0181 and 0.023h−1) were comparable to those attained in autotrophic cultures (without OMW) (0.0272 and 0.0249h−1). Nonetheless, significantly lower biomass productions were achieved by heterotrophic growth (0.22 and 0.35g·L−1 vs. 0.56 and 0.51g·L−1). Even though leading to lower biomass productions, heterotrophic growth ensured carbohydrate productions comparable to those attained by autotrophic growth (0.1 and 0.16 vs. 0.12 and 0.17g·L−1). Biodegradation of OMW phenols was found to be significantly affected by the concentration of inorganic nutrients. The inhibition of microalgal growth induced by phenols, and the interaction between phenol biodegradation and biomass production were analyzed.

Biodegradation of olive mill wastewater in a membrane bioreactor: acclimation of the biomass and constraints

AbstractIn order to overcome the toxic effect of olive mill wastewater (OMWW) on biomass during biological treatment, this work will test OMWW biodegradation in a membrane bioreactor (MBR) using an acclimation procedure and will study its constraints. Special focus will be put on soluble microbial products (SMP) analysis in MBR and their impact on membrane fouling. The study was realized in an external ceramic ultrafiltration MBR which offers more flexibility than the other biological treatments (i.e. independence between both hydraulic and sludge retention time) and a smaller footprint. Fed with a mass ratio of 40% OMWW/60% glucose, MBR biomass showed efficient chemical oxygen demand and polyphenols removal rates of, respectively, 90 and 65% despite a low activity of 3.2 mgO2 gMLVSS−1 h−1 due to the harsh and toxic environment. Moreover, HPLC analysis has showed a removal from the permeate of the major phenolic compounds including hydroxytyrosol, tyrosol, and caffeic acid. The monitoring of SMP concentra...

Development of pH adjustment-based operational strategy to increase total phenol removal rate in biodegradation of olive mill wastewater byRhodotorula glutinis

During the treatment of olive mill wastewater (OMW) by Rhodotorula glutinis, the pH of the medium increases in accordance with cell accumulation and biodegradation. Considering the pH of the medium as an indicator of biodegradation, an operation strategy depending on the pH adjustment of the batch medium with intermittent additions of OMW was developed. The addition of OMW into the biodegradation medium decreased the medium’s pH; fresh substrate was provided to the cells and the cells were kept active for biodegradation up to a critical pH value. This approach also provided the biodegradation of high volumes of undiluted OMW. About five- and twofold enhancements in total phenol removal rate were obtained in batch biodegradation but with interval feedings being carried out by free and immobilized cells, respectively, relative to the corresponding batch-wise operations.

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.

Biodegradation of olive mill wastewaters by a wild isolate of Candida oleophila

Olive mill wastewaters (OMW) resulting from the extraction of olive oil possess high organic loads and elevated contents in phenolic compounds, which are usually toxic and recalcitrant to biological wastewater treatments. In this work, a strain of Candida oleophila isolated from olive wastewaters was used for biological detoxification treatments of OMW samples. The effect of treatment with this isolate was evaluated by using germination tests, bioluminescence assays, and studies on mitochondrial bioenergetics. Incubation with the C. oleophila isolate was able to remove about 50% of the organic load, and 83% of total polyphenol content, from undiluted and non-supplemented OMW samples. Germination tests confirmed the reduction of toxicity of the treated effluent since when using diluted and treated OMW the germination index increased up to 32% when compared to the values obtained with untreated water. Treated OMW also decreased antimicrobial activity in about 50% as confirmed by the bioluminescence inhibition assay. Significant effects were also observed in mitochondrial bioenergetics. A decrease of toxicity toward two respiratory complexes, namely succinate dehydrogenase and ATPase, was recorded when using treated OMW. Overall, this C. oleophila isolate was able to remove organic matter and decrease toxicity of OMW effluents, showing promising abilities for future application in biological treatments.

Variations in phenolic compounds during biodegradation of olive mill wastewater by Debaryomyces hansenii

Variations in phenolic compounds during biodegradation of olive mill wastewater by Debaryomyces hansenii

Biodegradation of Olive Mill Wastewater by Trichosporon Cutaneum and Geotrichum Candidum

Olive oil production generates large volumes of wastewater. These wastewaters are characterised by high chemical oxygen demand (COD), high content of microbial growth-inhibiting compounds such as phenolic compounds and tannins, and dark colour. The aim of this study was to investigate biodegradation of olive mill wastewater (OMW) by yeasts Trichosporon cutaneum and Geotrichum candidum. The yeast Trichosporon cutaneum was used because it has a high potential to biodegrade phenolic compounds and a wide range of toxic compounds. The yeast Geotrichum candidum was used to see how successful it is in biodegrading compounds that give the dark colour to the wastewater. Under aerobic conditions, Trichosporon cutaneum removed 88 % of COD and 64 % of phenolic compounds, while the dark colour remained. Geotrichum candidum grown in static conditions reduced COD and colour further by 77 % and 47 %, respectively. This investigation has shown that Trichosporon cutaneum under aerobic conditions and Geotrichum candidum under facultative anaerobic conditions could be used successfully in a two-step biodegradation process. Further investigation of OMW treatment by selected yeasts should contribute to better understanding of biodegradation and decolourisation and should include ecotoxicological evaluation of the treated OMW.

Olive mill wastewater disposal in evaporation ponds in Sfax (Tunisia): moisture content effect on microbiological and physical chemical parameters

The study of the isotherms desorption of olive mill wastewater (OMW) was investigated to describe its water activity under different saturated environments. The microbial biodegradation of OMW during its storage in 5 evaporation ponds located in Agareb (Sfax-Tunisia) was carried out during the oil-harvesting year held 105 days in 2004. Gravimetric static method using saturated salt solutions was used and OMW as placed at 30 degrees C and under different water activities ranging from 0.11 to 0.90. Eight models were taken from the literature to describe experimental desorption isotherms. During storage, the evolution of physico-chemical parameters including pH, temperature, evaporation, humidity, total phosphorus, chemical oxygen demand (COD), biological oxygen demand (BOD) and phenols and three microbiological flora (aerobic mesophilic bacteria, yeasts and moulds) were considered. At 30 degrees C, when relative humidity increased in the experimented ponds of 69, 84 and 90%, the evaporation speed decreased from 1.24 x 10(-5) to 5 x 10(-6) cm(3) s(-1), from 6 x 10(-5) to 7 x 10(-6) cm(3) s(-1) and from 5 x 10(-6) to 1.1 x 10(-7) cm(3) s(-1) respectively. The desorption isotherm exhibited a sigmoidal curve corresponding to type II, typical of many organic material. The GAB and Peleg models gave the best fit for describing the relationship between the equilibrium moisture content and water activity in OMW (R (2) = 0.998). During the storage period, the analysis showed an increase of all the physico-chemical parameters studied, except phenols and total phosphorus concentrations. The microbiological study showed the predominance of yeasts and moulds and the decrease of bacteria population after 75 days reflecting both effect of recalcitrant compounds and the water activity on microbial growth.

Use of Geotrichum candidum for olive mill wastewater treatment in submerged and static culture

The production of lignin peroxidase (LiP), manganese peroxidase (MnP) and lipases by Geotrichum candidum were performed in order to control the decolourisation and biodegradation of olive mill wastewater (OMW). Optimisation of different factors showed that dilution, carbon and ammonium concentrations significantly affected decolourisation and activities of ligniolytic peroxidases (LiP and MnP) on OMW. Moreover, addition of olive oil and agitation improved the lipase production. Batch and continuous OMW treatments in settler or bubble column bioreactors showed high COD and colour removal efficiencies of 60% and 50%, respectively. Lipolytic activity was greater in the batch bubble column whereas, LiP and MnP productions were improved in the settler. The performance of the continuous processes decreased with the decrease of hydraulic retention time (HRT). It has been shown that decolourisation and biodegradation decreased with an average of 40% and 45%, respectively, by decreasing the HRT from 4 d to 1.7 d.

Aerobic biological treatment of olive mill wastewater by olive pulp bacteria

The capability of olive fruit bacteria to remove chemical oxygen demand (COD) and phenolic compounds from olive mill wastewater (OMW) using flasks and packed bed reactors was tested. Batch aerobic experiments were performed in flask reactors, with OMW at different dilutions (20%, 50%, and 100%). The maximum phenolic and dissolved COD removal reached up to 82–90% for the dilutions of 20%, 50%, and 100%, in 11, 23, and 30 days, respectively. Experiments were also conducted in a bench and a pilot-scale packed bed reactor, operated in the laboratory and at an olive mill, respectively. At 28 °C the maximum phenolic and dissolved COD removal, recorded at the bench-scale reactor, reached about 60% and 70%, respectively, for a time period of only 27 h. At the pilot-scale reactor, where the maximum daily temperature varied between 6 and 20 °C, the maximum phenolic and d-COD removal reached about 55% and 70% in 5 and 3 days, respectively. These results indicate an economically feasible method for OMW biodegradation.

Activity and elution profile of laccase during biological decolorization and dephenolization of olive mill wastewater

The performance and enzymatic strategy exhibited by basidiomycete Euc-1, a laccase producing strain, was investigated during the biodegradation of olive mill wastewater (OMW). This strain yielded better decolorization of solidified OMW than Phanerochaete chrysosporium and removed 90% of phenols (initial concentration=800 mg l −1), 73% of color (initial A 465=4.4), and 45% of chemical oxygen demand in batch cultures containing OMW. Since partial phenol removal occurred before the detection of enzymatic activity, no plausible correlation could be established between them. In contrast, decolorization occurred only after the detection of laccase activity and coincided with its production over time. Two laccase fractions (Lac1 and Lac2) were separated by chromatography. OMW strongly induced Lac2 that was almost absent in defined liquid medium. Furthermore, Lac2 was the main laccase fraction in the presence of OMW. This study pointed out that basidiomycete Euc-1 and its ligninolytic system could be a useful tool for the bioremediation of wastewater generated in the process of olive oil extraction.