The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform
Michele Besson - One of the best experts on this subject based on the ideXlab platform.
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catalytic wet air oxidation of olive Oil Mill Effluents 4 treatment and detoxification of real Effluents
Applied Catalysis B-environmental, 2008Co-Authors: Doan Pham Minh, Pierre Gallezot, Samia Azabou, Sami Sayadi, Michele BessonAbstract:Abstract Olive Oil Mill wastewater (OMW) generated by the olive Oil extraction industry constitutes a major pollutant, posing severe environmental threats. It contains a high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Platinum and ruthenium supported titania or zirconia were studied in the catalytic wet air oxidation (CWAO) of OMWs in a batch reactor and in a continuous trickle-bed reactor. CWAO experiments at 190 °C and 70 bar total air pressure confirmed the effective elimination of the TOC (total organic carbon) and of the phenolic content of actual diluted OMW. Simultaneously, toxicity towards Vibrio fischeri was reduced and a decrease in phytotoxicity occurred. The ruthenium catalysts were found stable over a long period of operation in a trickle-bed reactor. The biodegradability of the oxidized waste has been enhanced and this study also examined the feasibility of coupling CWAO and an anaerobic digestion treatment. The pretreatment of the OMW in the presence of a ruthenium catalyst reduced considerably the total phenolic contents of the wastewater, and produced an effluent suitable to be treated by anaerobic treatment with increased biomethane production compared to the untreated effluent.
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degradation of olive Oil Mill Effluents by catalytic wet air oxidation 2 oxidation of p hydroxyphenylacetic and p hydroxybenzoic acids over pt and ru supported catalysts
Applied Catalysis B-environmental, 2007Co-Authors: Pham D Minh, Pierre Gallezot, G Aubert, Michele BessonAbstract:Abstract Catalytic wet air oxidation of p -hydroxyphenylacetic acid and p -hydroxybenzoic acid, two important pollutants present in the olive Oil Mill wastewaters, was studied in a batch reactor using platinum and ruthenium catalysts supported on titanium and zirconium oxides at 140 °C and 50 bar of total air pressure. Reaction pathways for the oxidation of these two substrates were proposed, with formation of different aromatic compounds and short-chain organic acids through hydroxylation and decarboxylation reactions. It was observed that the conversion and the mineralization of these two substrates were markedly affected by the nature of the ruthenium precursor (RuCl 3 or Ru(NO)(NO 3 ) 3 ), with the non-chlorine containing salt giving the best performances. Calcination of the catalyst precursor before reduction was detrimental. The nature of the metallic precursor (H 2 PtCl 6 or Pt(NH 3 ) 4 (NO 3 ) 2 ) had little influence on the catalytic properties of platinum catalysts, whereas the textural properties of the support were an important factor.
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degradation of olive Oil Mill Effluents by catalytic wet air oxidation 1 reactivity of p coumaric acid over pt and ru supported catalysts
Applied Catalysis B-environmental, 2006Co-Authors: Doan Pham Minh, Pierre Gallezot, Michele BessonAbstract:Abstract The objective of this work was to investigate the catalytic wet air oxidation of p-coumaric acid, a biorecalcitrant phenolic compound typically found in olive Oil wastewaters in the presence of Pt and Ru supported catalysts. The influence of the operating variables were established. The most important intermediates determined by HPLC measurements suggest a rapid attack by oxygen of the side-chain of p-coumaric acid, and the mineralization proceeds through different aromatic compounds reacting further to aliphatic intermediates (mainly acids). Important mineralization yields were achieved in the presence of the catalysts at 140 °C and 50 bar air. The importance of the nature of the support (TiO2, ZrO2) on the adsorption of p-coumaric acid was demonstrated.
Pierre Gallezot - One of the best experts on this subject based on the ideXlab platform.
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catalytic wet air oxidation of olive Oil Mill Effluents 4 treatment and detoxification of real Effluents
Applied Catalysis B-environmental, 2008Co-Authors: Doan Pham Minh, Pierre Gallezot, Samia Azabou, Sami Sayadi, Michele BessonAbstract:Abstract Olive Oil Mill wastewater (OMW) generated by the olive Oil extraction industry constitutes a major pollutant, posing severe environmental threats. It contains a high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Platinum and ruthenium supported titania or zirconia were studied in the catalytic wet air oxidation (CWAO) of OMWs in a batch reactor and in a continuous trickle-bed reactor. CWAO experiments at 190 °C and 70 bar total air pressure confirmed the effective elimination of the TOC (total organic carbon) and of the phenolic content of actual diluted OMW. Simultaneously, toxicity towards Vibrio fischeri was reduced and a decrease in phytotoxicity occurred. The ruthenium catalysts were found stable over a long period of operation in a trickle-bed reactor. The biodegradability of the oxidized waste has been enhanced and this study also examined the feasibility of coupling CWAO and an anaerobic digestion treatment. The pretreatment of the OMW in the presence of a ruthenium catalyst reduced considerably the total phenolic contents of the wastewater, and produced an effluent suitable to be treated by anaerobic treatment with increased biomethane production compared to the untreated effluent.
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degradation of olive Oil Mill Effluents by catalytic wet air oxidation 2 oxidation of p hydroxyphenylacetic and p hydroxybenzoic acids over pt and ru supported catalysts
Applied Catalysis B-environmental, 2007Co-Authors: Pham D Minh, Pierre Gallezot, G Aubert, Michele BessonAbstract:Abstract Catalytic wet air oxidation of p -hydroxyphenylacetic acid and p -hydroxybenzoic acid, two important pollutants present in the olive Oil Mill wastewaters, was studied in a batch reactor using platinum and ruthenium catalysts supported on titanium and zirconium oxides at 140 °C and 50 bar of total air pressure. Reaction pathways for the oxidation of these two substrates were proposed, with formation of different aromatic compounds and short-chain organic acids through hydroxylation and decarboxylation reactions. It was observed that the conversion and the mineralization of these two substrates were markedly affected by the nature of the ruthenium precursor (RuCl 3 or Ru(NO)(NO 3 ) 3 ), with the non-chlorine containing salt giving the best performances. Calcination of the catalyst precursor before reduction was detrimental. The nature of the metallic precursor (H 2 PtCl 6 or Pt(NH 3 ) 4 (NO 3 ) 2 ) had little influence on the catalytic properties of platinum catalysts, whereas the textural properties of the support were an important factor.
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degradation of olive Oil Mill Effluents by catalytic wet air oxidation 1 reactivity of p coumaric acid over pt and ru supported catalysts
Applied Catalysis B-environmental, 2006Co-Authors: Doan Pham Minh, Pierre Gallezot, Michele BessonAbstract:Abstract The objective of this work was to investigate the catalytic wet air oxidation of p-coumaric acid, a biorecalcitrant phenolic compound typically found in olive Oil wastewaters in the presence of Pt and Ru supported catalysts. The influence of the operating variables were established. The most important intermediates determined by HPLC measurements suggest a rapid attack by oxygen of the side-chain of p-coumaric acid, and the mineralization proceeds through different aromatic compounds reacting further to aliphatic intermediates (mainly acids). Important mineralization yields were achieved in the presence of the catalysts at 140 °C and 50 bar air. The importance of the nature of the support (TiO2, ZrO2) on the adsorption of p-coumaric acid was demonstrated.
Doan Pham Minh - One of the best experts on this subject based on the ideXlab platform.
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catalytic wet air oxidation of olive Oil Mill Effluents 4 treatment and detoxification of real Effluents
Applied Catalysis B-environmental, 2008Co-Authors: Doan Pham Minh, Pierre Gallezot, Samia Azabou, Sami Sayadi, Michele BessonAbstract:Abstract Olive Oil Mill wastewater (OMW) generated by the olive Oil extraction industry constitutes a major pollutant, posing severe environmental threats. It contains a high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Platinum and ruthenium supported titania or zirconia were studied in the catalytic wet air oxidation (CWAO) of OMWs in a batch reactor and in a continuous trickle-bed reactor. CWAO experiments at 190 °C and 70 bar total air pressure confirmed the effective elimination of the TOC (total organic carbon) and of the phenolic content of actual diluted OMW. Simultaneously, toxicity towards Vibrio fischeri was reduced and a decrease in phytotoxicity occurred. The ruthenium catalysts were found stable over a long period of operation in a trickle-bed reactor. The biodegradability of the oxidized waste has been enhanced and this study also examined the feasibility of coupling CWAO and an anaerobic digestion treatment. The pretreatment of the OMW in the presence of a ruthenium catalyst reduced considerably the total phenolic contents of the wastewater, and produced an effluent suitable to be treated by anaerobic treatment with increased biomethane production compared to the untreated effluent.
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degradation of olive Oil Mill Effluents by catalytic wet air oxidation 1 reactivity of p coumaric acid over pt and ru supported catalysts
Applied Catalysis B-environmental, 2006Co-Authors: Doan Pham Minh, Pierre Gallezot, Michele BessonAbstract:Abstract The objective of this work was to investigate the catalytic wet air oxidation of p-coumaric acid, a biorecalcitrant phenolic compound typically found in olive Oil wastewaters in the presence of Pt and Ru supported catalysts. The influence of the operating variables were established. The most important intermediates determined by HPLC measurements suggest a rapid attack by oxygen of the side-chain of p-coumaric acid, and the mineralization proceeds through different aromatic compounds reacting further to aliphatic intermediates (mainly acids). Important mineralization yields were achieved in the presence of the catalysts at 140 °C and 50 bar air. The importance of the nature of the support (TiO2, ZrO2) on the adsorption of p-coumaric acid was demonstrated.
Mauro Majone - One of the best experts on this subject based on the ideXlab platform.
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Exploiting olive Oil Mill Effluents as a renewable resource for production of biodegradable polymers through a combined anaerobic-aerobic process
Journal of Chemical Technology and Biotechnology, 2009Co-Authors: Mario Beccari, Dominique Dionisi, Francesca Fava, S. Lampis, Lucie Bertin, Francesca Valentino, Mauro Majone, Giovanni Vallini, Michael VillanoAbstract:BACKGROUND: The performance of a three-stage process for polyhydroxyalkanoate (PHA) bioproduction from olive Oil Mill Effluents (OME) has been investigated. In the first anaerobic stage OME were fermented in a packed bed biofilm reactor into volatile fatty acids (VFAs). This VFA-rich effluent was fed to the second stage, operated in an aerobic sequencing batch reactor (SBR), to enrich mixed cultures able to store PHAs. Finally, the storage response of the selected consortia was exploited in the third aerobic stage, operated in batch conditions.RESULTS: The anaerobic stage increased the VFA percentage in the OME from 18% to ∼32% of the overall chemical oxygen demand (COD). A biomass with high storage response was successfully enriched in the SBR fed with the fermented OME at an organic load rate of 8.5 gCOD L−1 d−1, with maximum storage rate and yield (146 mgCOD gCOD−1 h−1 and 0.36 COD COD−1, respectively) very similar to those obtained with a synthetic VFA mixture. By means of denaturing gradient gel electrophoresis (DGGE) analysis, different bacterial strains were identified during the two SBR runs: Lampropedia hyalina and Candidatus Meganema perideroedes, with the synthetic feed or the fermented OMEs, respectively. In the third stage, operated at increasing loads, the maximum concentration of the PHA produced increased linearly with the substrate fed. Moreover, about half of the stored PHAs were produced from substrates other than VFAs, mostly alcohols.CONCLUSION: The results obtained indicate that the process is effective for simultaneous treatment of OME and their valorization as a renewable resource for PHA production. Copyright © 2009 Society of Chemical Industry
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olive Oil Mill Effluents as a feedstock for production of biodegradable polymers
Water Research, 2005Co-Authors: Dominique Dionisi, Mauro Majone, G Carucci, Petrangeli M Papini, C Riccardi, F CarrascoAbstract:The aim of the present paper was to study the feasibility of using olive Oil Mill Effluents (OMEs) as a substrate in biodegradable polymer production. OMEs were anaerobically fermented to obtain volatile fatty acids (VFAs), which are the most highly used substrate for polyhydroxyalkanotes (PHAs) production. The anaerobic fermentation step was studied both without pretreatment and with different pretreatments (i.e., centrifugation, bentonite addition, and bentonite addition followed by centrifugation) and at various concentrations (28.5, 36.7 and 70.4 g CODL(-1)). During fermentation, VFA concentration was determined (7-16 g CODL(-1)) as well as the corresponding yield with respect to initial COD (22-44%). At all initial concentrations, centrifugation pretreatment (with or without previous addition of bentonite) significantly increased the final VFA concentration and yield, whereas the addition of bentonite alone had no influence. Moreover, centrifugation pretreatment led to a different acid distribution, which affected the hydroxyvalerate (HV) content within the obtained copolymer poly beta-(hydroxybutyrate-hydroxyvalerate) [P(HB-HV)]. OMEs were tested for PHA production by using a mixed culture from an aerobic SBR. Centrifuged OMEs, both with or without fermentation, were tested. PHAs were produced from both matrices, but with fermented OMEs PHA production was much higher, because of the higher VFA concentration. The initial specific rate of PHA production obtained with fermented OMEs was approximately 420 mg COD g COD(-1)h(-1) and the maximum HV content within the copolymer was about 11% (on a molar basis). The HV monomer was produced only until propionic acid remained present in the medium.
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removal of molecular weight fractions of cod and phenolic compounds in an integrated treatment of olive Oil Mill Effluents
Biodegradation, 2002Co-Authors: Mario Beccari, Mauro Majone, G Carucci, A M Lanz, Petrangeli M PapiniAbstract:Previous works (Beccari et al. 1999b; Beccari et al. 2001a; Beccari et al. 2001b)on the anaerobic treatment of olive Oil Mill Effluents (OME) have shown: (a) apre-treatment based on the addition of Ca(OH)2 and bentonite was able toremove lipids (i.e. the most inhibiting substances present in OME) almostquantitatively; (b) the mixture OME – Ca(OH)2 – bentonite, fed to amethanogenic reactor without providing an intermediate phase separation,gave way to high biogas production even at very low dilution ratios; (c) theeffluent from the methanogenic reactor still contained significant concentrationsof residual phenolic compounds (i.e. the most biorecalcitrant substances present inOME). Consequently, this paper was aimed at evaluating the fate of the phenolicfractions with different molecular weights during the sequence of operations(adsorption on bentonite, methanogenic digestion, activated sludge post-treatment).The results show that a very high percentage (above 80%) of the phenolic fractionbelow 500 D is removed by the methanogenic process whereas the phenolic fractionsabove 1,000 D are significantly adsorbed on bentonite; the 8-day activated sludgepost-treatment allows an additional removal of about 40% of total filtered phenoliccompounds. The complete sequence of treatments was able to remove more than the96% of the phenolic fraction below 500 D (i.e. the most toxic fraction towards plantgermination). Preliminary respirometric tests show low level of inhibition exerted bythe effluent from the methanogenic reactor on aerobic activated sludges taken fromfull-scale municipal wastewater plants.
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enhancement of anaerobic treatability of olive Oil Mill Effluents by addition of ca oh 2 and bentonite without intermediate solid liquid separation
Water Science and Technology, 2001Co-Authors: Mario Beccari, Mauro Majone, L Torrisi, Petrangeli M PapiniAbstract:Previous work on the anaerobic treatment of olive Oil Mill Effluents (OME) have shown : (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH) 2 and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bioconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH) 2 and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment : the best results in terms of methane production were obtained by addition of Ca(OH) 2 up to pH 6.5 and of 10 g L -1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous methanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m -3 d -1 and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH 4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor).
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role of lipids and phenolic compounds in the anaerobic treatment of olive Oil Mill Effluents
Environmental Technology, 1999Co-Authors: Mario Beccari, Mauro Majone, G Carucci, L TorrisiAbstract:The inhibitory effects of olive Oil Mill Effluents (OME) on methanogenesis were studied by using p-hydroxybenzoic acid (HBA) and oleic acid (OA) as model compounds for phenolic compounds and lipids respectively. The addition of HBA (0.3 g l−1) to diluted OME (5.7 g COD l−1) had a negligible effect on methanogenesis in terms of kinetics and final methane yield. Strong inhibition was observed only at high HBA concentrations (6 g l−1). The OA inhibited methane production much more strongly. Indeed, 0.35 g l−1 of OA were able to double the lag phase for methanogenesis from diluted OME. With both compounds, the presence of an easily biodegradable co-substrate (glucose) did not increase the rate of substrate degradation nor methane formation. OME acidogenesis was significantly less sensitive than methanogenesis to the inhibitory effects exerted by OA and HBA, even at relatively high concentrations of the model compounds.
Mario Beccari - One of the best experts on this subject based on the ideXlab platform.
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Exploiting olive Oil Mill Effluents as a renewable resource for production of biodegradable polymers through a combined anaerobic-aerobic process
Journal of Chemical Technology and Biotechnology, 2009Co-Authors: Mario Beccari, Dominique Dionisi, Francesca Fava, S. Lampis, Lucie Bertin, Francesca Valentino, Mauro Majone, Giovanni Vallini, Michael VillanoAbstract:BACKGROUND: The performance of a three-stage process for polyhydroxyalkanoate (PHA) bioproduction from olive Oil Mill Effluents (OME) has been investigated. In the first anaerobic stage OME were fermented in a packed bed biofilm reactor into volatile fatty acids (VFAs). This VFA-rich effluent was fed to the second stage, operated in an aerobic sequencing batch reactor (SBR), to enrich mixed cultures able to store PHAs. Finally, the storage response of the selected consortia was exploited in the third aerobic stage, operated in batch conditions.RESULTS: The anaerobic stage increased the VFA percentage in the OME from 18% to ∼32% of the overall chemical oxygen demand (COD). A biomass with high storage response was successfully enriched in the SBR fed with the fermented OME at an organic load rate of 8.5 gCOD L−1 d−1, with maximum storage rate and yield (146 mgCOD gCOD−1 h−1 and 0.36 COD COD−1, respectively) very similar to those obtained with a synthetic VFA mixture. By means of denaturing gradient gel electrophoresis (DGGE) analysis, different bacterial strains were identified during the two SBR runs: Lampropedia hyalina and Candidatus Meganema perideroedes, with the synthetic feed or the fermented OMEs, respectively. In the third stage, operated at increasing loads, the maximum concentration of the PHA produced increased linearly with the substrate fed. Moreover, about half of the stored PHAs were produced from substrates other than VFAs, mostly alcohols.CONCLUSION: The results obtained indicate that the process is effective for simultaneous treatment of OME and their valorization as a renewable resource for PHA production. Copyright © 2009 Society of Chemical Industry
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removal of molecular weight fractions of cod and phenolic compounds in an integrated treatment of olive Oil Mill Effluents
Biodegradation, 2002Co-Authors: Mario Beccari, Mauro Majone, G Carucci, A M Lanz, Petrangeli M PapiniAbstract:Previous works (Beccari et al. 1999b; Beccari et al. 2001a; Beccari et al. 2001b)on the anaerobic treatment of olive Oil Mill Effluents (OME) have shown: (a) apre-treatment based on the addition of Ca(OH)2 and bentonite was able toremove lipids (i.e. the most inhibiting substances present in OME) almostquantitatively; (b) the mixture OME – Ca(OH)2 – bentonite, fed to amethanogenic reactor without providing an intermediate phase separation,gave way to high biogas production even at very low dilution ratios; (c) theeffluent from the methanogenic reactor still contained significant concentrationsof residual phenolic compounds (i.e. the most biorecalcitrant substances present inOME). Consequently, this paper was aimed at evaluating the fate of the phenolicfractions with different molecular weights during the sequence of operations(adsorption on bentonite, methanogenic digestion, activated sludge post-treatment).The results show that a very high percentage (above 80%) of the phenolic fractionbelow 500 D is removed by the methanogenic process whereas the phenolic fractionsabove 1,000 D are significantly adsorbed on bentonite; the 8-day activated sludgepost-treatment allows an additional removal of about 40% of total filtered phenoliccompounds. The complete sequence of treatments was able to remove more than the96% of the phenolic fraction below 500 D (i.e. the most toxic fraction towards plantgermination). Preliminary respirometric tests show low level of inhibition exerted bythe effluent from the methanogenic reactor on aerobic activated sludges taken fromfull-scale municipal wastewater plants.
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enhancement of anaerobic treatability of olive Oil Mill Effluents by addition of ca oh 2 and bentonite without intermediate solid liquid separation
Water Science and Technology, 2001Co-Authors: Mario Beccari, Mauro Majone, L Torrisi, Petrangeli M PapiniAbstract:Previous work on the anaerobic treatment of olive Oil Mill Effluents (OME) have shown : (a) lipids, even if more easily degraded than phenols, were potentially capable of inhibiting methanogenesis more strongly; (b) a pretreatment based on addition of Ca(OH) 2 and bentonite removed lipids almost quantitatively; (c) preliminary biotreatability tests performed on the pretreated OME showed high bioconversion into methane at very low dilutions ratios, especially when the mixture (OME, Ca(OH) 2 and bentonite) was fed to the biological treatment without providing an intermediate phase separation. This paper was directed towards two main aims: (a) to optimize pretreatment : the best results in terms of methane production were obtained by addition of Ca(OH) 2 up to pH 6.5 and of 10 g L -1 of bentonite; (b) to evaluate the enhancement of anaerobic treatability of OME pretreated under optimized conditions in a lab-scale continuous methanogenic reactor fed with the substrate without intermediate solid/liquid separation: very satisfactory performances were obtained (at an organic load of 8.2 kg COD m -3 d -1 and at a dilution ratio of 1:1.5 total COD removal was 91%, biogas production was 0.80 g CH 4 (as COD)/g tot. COD, lipids removal was 98%, phenols removal was 63%). The results confirm the double role played by bentonite (adsorption of the inhibiting substances and release of the adsorbed biodegradable matter in the methanogenic reactor).
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role of lipids and phenolic compounds in the anaerobic treatment of olive Oil Mill Effluents
Environmental Technology, 1999Co-Authors: Mario Beccari, Mauro Majone, G Carucci, L TorrisiAbstract:The inhibitory effects of olive Oil Mill Effluents (OME) on methanogenesis were studied by using p-hydroxybenzoic acid (HBA) and oleic acid (OA) as model compounds for phenolic compounds and lipids respectively. The addition of HBA (0.3 g l−1) to diluted OME (5.7 g COD l−1) had a negligible effect on methanogenesis in terms of kinetics and final methane yield. Strong inhibition was observed only at high HBA concentrations (6 g l−1). The OA inhibited methane production much more strongly. Indeed, 0.35 g l−1 of OA were able to double the lag phase for methanogenesis from diluted OME. With both compounds, the presence of an easily biodegradable co-substrate (glucose) did not increase the rate of substrate degradation nor methane formation. OME acidogenesis was significantly less sensitive than methanogenesis to the inhibitory effects exerted by OA and HBA, even at relatively high concentrations of the model compounds.
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integrated treatment of olive Oil Mill Effluents effect of chemical and physical pretreatment on anaerobic treatability
Water Science and Technology, 1999Co-Authors: Mario Beccari, Mauro Majone, C Riccardi, F Savarese, L TorrisiAbstract:Difficulties met in the anaerobic treatment of olive Oil Mill Effluents (OME) suggest the use of a chemico-physical pretreatment for the removal of biorecalcitrant and/or inhibiting substances (essentially lipids and polyphenols) as selectively as possible before anaerobic digestion. Laboratory scale experiments were carried out in order to identify pretreatment type and conditions capable of optimizing OME anaerobic digestion in terms both of kinetics and methane yield. Ultrafiltration, even if it allowed very high removals of lipids and polyphenols, was affected by poor selectivity (indeed, large amounts of biodegradable COD were also removed). Centrifugation turned out to be preferable to sedimentation owing to smaller volumes of separated phase. Results of great significance were obtained by adding Ca(OH)2 (up to pH 6.5) and 15 g/l of bentonite, and then feeding the mixture to the biological treatment without providing an intermediate phase separation. Indeed, the biodegradable matter adsorbed on the surface of bentonite was gradually released during the biotreatability test, thus allowing the same methane yield (referred to the total COD contained in untreated OME) both in scarcely diluted (1: 1.5) pretreated OME and in very diluted (1: 12) untreated OME. Application of a continuous process combining pretreatment (with Ca(OH)2 and bentonite) and anaerobic digestion without intermediate phase separation is suggested.
