Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform ch... more Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform chemicals. However, the major challenges in this fermentation are limited product yields and productivities faced due to product inhibition and difficulty in carboxylate separation and recovery from fermentation broths. To mitigate the above problems, process optimization via integrated fermentation-separation i.e. in-situ product recovery (ISPR) systems can be considered. As a first step towards development of such coupled carboxylate bioprocesses, this study aimed to provide a detailed analysis of extraction behaviour of a wide array of extractants and diluents for C2-C6 carboxylates in synthetic solutions and real effluent from acidogenic fermentation. Compared to physical extraction without extractant, a 75-85% increase was achieved when using reactive extraction (RE) and the difference was more pronounced for short chain carboxylates, particularly at pH 4.5. Distribution coefficients and extraction efficiencies increased with increasing extractant concentration and reached an equilibrium at molar ratio of 1:2. Aliquat 336 and tri-octylphosphine oxide solved in methyloctanoate emerged as the best RE systems and yielded high extraction efficiencies of 11.5 and 29.5 (acetic acid) to almost 100 (caproic acid) respectively. Testing with real fermentation effluent demonstrated similar high extraction yields as observed on synthetic solutions. Potential toxicity of RE on acidogenic fermentation was also investigated which suggested the application of an external ISPR configuration for these coupled bioprocesses.
Environmental Engineering and Management Journal, 2013
Pesticides can be considered useful to eliminate pests, but can also induce negative effects to t... more Pesticides can be considered useful to eliminate pests, but can also induce negative effects to the processes of germination, growth and development of plants or disrupt some physiological and metabolic processes. By studying the effect of pesticides on treated seeds germination, and determination of growth indices, it was possible to evaluate the positive or negative influence or toxicity of the chemical compounds. The aim of this research is to highlight the effects of differentiated treatment with two types of pesticides with their common name Actara 25 WG and Topsin AL 70 PU on germination, growth and development of wheat plantlets. The experiment included 1300 wheat seeds which were divided into thirteen groups, the first group of 100 wheat seeds was considered the control sample and the others were divided equally into twelve groups which were treated with three different concentration dose of each pesticide, one less, one optimal, and one more compared to the optimal one for treatment, acting for a period of 14 and 24 hours. Biometric examinations of seedlings were subjected to analysis of variance (ANOVA) followed by Tukey's B test and analysis of covariance (ANCOVA). The concentration of each pesticides and acting time may also influence the allometric relationship between stem weights and stem length, root weight and number of roots, in different ways. It was observed the existence of a relationship between pesticides concentration, exposure time and weight of steam, in case of Topsin fungicide, under the influence of steam length, the observed power of this dependence being very high, 0.975.
The production of oxygenated bio-additives for traditional fuels represents a key challenge due t... more The production of oxygenated bio-additives for traditional fuels represents a key challenge due to their depletion in the near-future and their positive contribution to the reduction in environmental pollution. The present study considers the synthesis of 1-hexanol/hexyl hexanoate mixtures, two oxygenated Diesel bio-additives produced through the hydrogenation of hexanoic acid, obtainable from the fermentation of a wide variety of waste biomasses. In our case, crude hexanoic acid was produced through the fermentation of grape pomace, an abundant Italian agrifood waste. Commercial 5 wt% Re/γ-Al2O3 was adopted for the catalytic hydrogenation of crude hexanoic acid, and the support acidity allowed the tuning of the reaction selectivity toward the formation of hexyl hexanoate, instead of 1-hexanol, reaching yields of 40 and 25 mol%, respectively. The effects of each bio-additive on Diesel engine performance and exhaust emissions (soot, nitrogen oxides, carbon monoxide, unburned hydrocar...
The transition from fossil resources to renewable ones represents a pressing need. The acidogenic... more The transition from fossil resources to renewable ones represents a pressing need. The acidogenic fermentation of biomass-derived ethanol to carboxylic acids represents a novel and smart possibility, opening the way for the production of further value-added bio-products through cascade chemical approaches. In this work, the hydrogenation of commercial hexanoic acid to give 1-hexanol/hexyl hexanoate mixtures was preliminary studied in the presence of commercial rhenium catalysts (Re2O7 and 5 wt% Re/C), which resulted as mainly active and selective towards 1-hexanol. On the other hand, the use of niobium phosphate as the acid co-catalyst markedly shifted the selectivity towards hexyl hexanoate. Moreover, 5 wt% Re/C and physical mixtures of (5 wt% Re/C + niobium phosphate) were further tested for the hydrogenation of crude hexanoic acid obtained through fermentation of white grape pomace, confirming the promising performance of these catalytic systems and their recyclability. For the f...
Biorefinery has been defined as the sustainable conversion of biomass towards a spectrum of bioba... more Biorefinery has been defined as the sustainable conversion of biomass towards a spectrum of biobased products for different industrial fields, among which the food and feed, chemical, and energetic sectors. This concept was assessed at the beginning of the century and it was initially related to biofuels production through processing of dedicated biomass, i.e., sugar or oleaginous crops specifically cultivated for bioethanol and biodiesel production, respectively. Despite the consequent development of strategies for culture intensification, biofuel costs have not been competitive when compared with fossil-based counterparts. Low energy product values have contributed to this evidence; furthermore, with respect to conventional refinery fed with fossil sources, biofuel production needs to face up to higher costs associated with related raw materials, due to the facts that they are typically seasonal, widely distributed in larger territories, complex and variable in composition.
Environmental Engineering and Management Journal, 2013
A large variety of agro-wastes are actually investigated for their reliability as renewable sourc... more A large variety of agro-wastes are actually investigated for their reliability as renewable sources: the possibility to employ some organic residues for the production of biomolecules, biofuels and biomaterials has fostered the born of the concept of second generation biorefineries, which differ from the first generation processes, since non dedicated crops are used as the feedstock. To this aim, Olive Mill Wastewaters (OMWs) are the most investigated wastes, due to their high organic content and to a high concentration of polyphenols, compounds that are natural antioxidant. If on the one hand OMWs are recalcitrant to biodegradation and their environmental impact can represent a serious issue, on the other hand these wastes show a biochemically interesting composition, rich of sugars, lipids, alcohols and organic acids. Recent studies have demonstrated that a lot of processes can be applied to OMWs, which can be exploited for the recovery of polyphenols, production of biofuels or ch...
Environmental Engineering and Management Journal, 2013
1 DICAM, University of Bologna, via Terracini 28, I-40131, Bologna, Italy 2 Eridania Sadam S.p.A,... more 1 DICAM, University of Bologna, via Terracini 28, I-40131, Bologna, Italy 2 Eridania Sadam S.p.A, Via degli Agresti 4/6, I-40123, Bologna, Italy 3 Sebigas S.p.A., Via Santa Rita, 21057, Olgiate Olona (VA), Italy 4 Sadam Engineering s.r.l., Via degli Agresti 4/6, I-40123, Bologna, Italy Stefano Rebecchi1, Lorenzo Bertin1, Veronica Vallini2, Giacomo Bucchi3, Fabrizio Bartocci4, Fabio Fava1 Rimini, 7 Novembre 2013
Biogas upgrading from anaerobic digestion of waste frying oils (WFO) was accessed in this study. ... more Biogas upgrading from anaerobic digestion of waste frying oils (WFO) was accessed in this study. For that, two bioreactors (Rb-biogas-lift bioreactor with gas and liquid recirculation, Rc-control reactor with liquid recirculation) were fed three times per week, with a mixture of WFO, glycerol and volatile fatty acids (VFA). Rb produced 1.4 times more biogas with higher methane content (79%) than Rc (67%). Higher relative abundance of hydrogenotrophic methanogens (34%e39%) was observed in Rb, when compared to Rc (16%e21%). The relative abundance of Sprochaetia class, which includes some homoacetogens/ syntrophic acetate oxidizing genera, was also higher in Rb. This work shows that biogas recirculation applied in the biogas-lift bioreactor facilitated WFO degradation, most probably due to the selective enrichment of hydrogenotrophic methanogens. Recirculation of CO 2 present in the biogas and reverse homoacetogenesis (i.e. syntrophic acetate oxidation) seem to be the main factors involved in the stimulation of hydrogenotrophic methanogenesis.
Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform ch... more Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform chemicals. However, the major challenges in this fermentation are limited product yields and productivities faced due to product inhibition and difficulty in carboxylate separation and recovery from fermentation broths. To mitigate the above problems, process optimization via integrated fermentation-separation i.e. in-situ product recovery (ISPR) systems can be considered. As a first step towards development of such coupled carboxylate bioprocesses, this study aimed to provide a detailed analysis of extraction behaviour of a wide array of extractants and diluents for C2-C6 carboxylates in synthetic solutions and real effluent from acidogenic fermentation. Compared to physical extraction without extractant, a 75-85% increase was achieved when using reactive extraction (RE) and the difference was more pronounced for short chain carboxylates, particularly at pH 4.5. Distribution coefficients and extraction efficiencies increased with increasing extractant concentration and reached an equilibrium at molar ratio of 1:2. Aliquat 336 and tri-octylphosphine oxide solved in methyloctanoate emerged as the best RE systems and yielded high extraction efficiencies of 11.5 and 29.5 (acetic acid) to almost 100 (caproic acid) respectively. Testing with real fermentation effluent demonstrated similar high extraction yields as observed on synthetic solutions. Potential toxicity of RE on acidogenic fermentation was also investigated which suggested the application of an external ISPR configuration for these coupled bioprocesses.
Wastewater reclamation and reuse became essential to meet the more restrictive discharge limits a... more Wastewater reclamation and reuse became essential to meet the more restrictive discharge limits and to overcome the water scarcity issue. Industrial wastewaters treated by membrane bioreactor (MBR) systems generally include high amounts of salinity, nutrients as nitrogen and phosphorus, heavy metals, hardness, etc. which in most cases, do not fit with discharge and reuse limits. Membrane processes like nanofiltration (NF) and reverse osmosis (RO) are widely adopted for secondary effluent treatment producing high-quality water. Since untreated brine can damage the environment, this work focused on reduction of amount of concentrate by working in membrane-in-series configuration. Tests with two membrane-in-series (NF90+NF90, BW30+BW30, BW30+NF270 combinations) were performed as the concentrate stream of the first one was fed to the second one. Water recoveries were over 80% in each experiment. Water fluxes of 44.0, 41.4 and 73.4 L/m 2 .h were obtained with NF90+NF90, BW30+BW30, BW30+NF270 combinations, respectively. Also, salinity rejections represented by electrical conductivity were 93.0%, 97.4% and 42.4% for NF90+NF90, BW30+BW30, BW30+NF270 configurations, respectively. Permeates of BW30+BW30 and NF90+NF90 combinations seem to be useable for agricultural irrigation although soil permeability is an important issue, not only ion concentrations and salinity of water used.
Clean water sources are quickly depleted since the industrial revolution due to climate change an... more Clean water sources are quickly depleted since the industrial revolution due to climate change and overpopulation. Use of potable water for agricultural irrigation is under imminent threat. Therefore, it is important to obtain irrigation water from alternative sources such as industrial wastewaters. On the other hand, industrial wastewaters have to be treated well otherwise they can pollute the environment and decrease the irrigation potential of soil. Membrane bioreactor (MBR) effluents of industrial wastewaters have a great potential to be used in agricultural irrigation. In this study, the permeates of NF270 and BW30-RO membranes were produced from MBR effluent discharged from Wastewater Treatment Plant of ITOB Organized Industrial Zone, Menderes, Izmir. They were evaluated for their reuse in agricultural irrigation. While doing this evaluation, effect of operating pressure on water quality was also investigated. It was found that the RO permeate is not suitable to reuse in irrigation. On the other hand, the NF permeate could be suitable for medium-salinity tolerant plants.
Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed ... more Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed bed bioreactor was set-up to digest anaerobically under acidogenic condition a water solution of a cheese whey powder. Batch tests pointed out that the whole VFAs production process occurred via two sequential phases: (a) conversion of lactose into lactic acid; (b) conversion of lactic acid into a mixture of VFAs. Furthermore, the same tests showed that the ceramic material Vukopor S10 can be used as an effective support for cell immobilization in anaerobic fermentation processes. The effect of the hydraulic retention time (HRT) and organic loading rate (OLR) were then studied in a bench-top bioreactor operated continuously. By a HRT of 6 days, OLR of 25 glactose.L -1 .d -1 and pH 5.8-6, 16 g.L -1 of total VFAs were produced, with a yield higher than 75% (CmolVFAs.Cmollactose -1 ). Characterization with Illumina-based sequencing suggested that high VFAs productivities were obtained when microbial community structures developed in the biofilm reactor were highly enriched in few genera.
International Journal of Chemical Engineering, 2016
The goals of this work were (i) to compare two anion ion exchange resins (IRA958 Cl and IRA67) an... more The goals of this work were (i) to compare two anion ion exchange resins (IRA958 Cl and IRA67) and a nonionic resin (XAD16) in terms of phenolic compounds adsorption capacity from olive mill wastewater and (ii) to compare the adsorption capacity of the best resin on columns of different length. The ion exchange resins performed worse than nonionic XAD16 in terms of resin utilization efficiency (20% versus 43%) and phenolic compounds/COD enrichment factor (1.0 versus 2.5). The addition of volatile fatty acids did not hinder phenolic compounds adsorption on either resin, suggesting a noncompetitive adsorption mechanism. A pH increase from 4.9 to 7.2 did not affect the result of this comparison. For the best performing resin (XAD16), an increase in column length from 0.5 to 1.8 m determined an increase in resin utilization efficiency (from 12% to 43%), resin productivity (from 3.4 to 7.6 gsorbed phenolics/kgresin), and phenolics/COD enrichment factor (from 1.2 to 2.5). An axial disper...
Rotating Algal Biofilm Reactor (RABR) technology was successfully employed in an effective strate... more Rotating Algal Biofilm Reactor (RABR) technology was successfully employed in an effective strategy to couple the removal of wastewater nutrients with accumulation of valuable bioproducts by grown algae. A secondary stage municipal wastewater was fed to the developed system and the effects of the hydraulic retention time (HRT) parameter on both nutrient removal and bioproduct production were evaluated under fed-batch operation mode. Two sets of bench scale RABRs were designed and operated with HRTs of 2 and 6 days in order to provide competitive environment for algal growth. The HRT significantly affected nitrogen and phosphorus uptakes along with lipid and starch accumulations by microalgae in harvested biofilms. Domination of nitrogen removal in 2-day HRT with higher lipid accumulation (20% on dried weight basis) and phosphorus removal in 6-day HRT with higher starch production (27% on dried weight basis) was observed by comparing the performances of the RABRs in duplicate runs.
Electrodialysis (ED) is applied for the first time as a separation-concentration step of the Vola... more Electrodialysis (ED) is applied for the first time as a separation-concentration step of the Volatile Fatty Acids (VFAs) enriched effluent resulting from fermentation of olive mill wastewaters. The process would represent a key step of an integrated multi-purpose biorefinery scheme including the biotechnological production of polyhydroxyalkanoates from acidified bioresidues. A feasibility study is introduced by testing separation efficiency of membranes with synthetic model solutions of different compositions (sodium acetate and NaCl, or acetic-propionic-butyric acids with NaCl) and with actual OMW (a complex mixture of sodium salts of acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic, caproic, eptanoic acids, NaCl and other electrolytes). Experiments were performed at room temperature in a lab-scale 2-compartments ED stack, containing Neosepta AMX-CMX membranes, at constant current density (31 A/m 2 ). Membrane resistance was tested by performing additional ED experiments according to a proper protocol developed in this work. Removal of VFAs from actual OMW is feasible; no evidence of remarkable damages nor losses of membrane performance were observed after dedicated trials. Under the operative conditions investigated, VFAs removals ranged from 30 to 35%, resulting in a concentration factor between 1.2 and 1.5 with respect to the initial mother solution. Chloride removal was remarkably high and it was greatly favoured at the beginning of operation; competition between chloride and acidic anions was remarkable as far as chloride concentration was high, whereas acidic anions transport across the membrane increased after NaCl removal overcame 50%. Removal and concomitant concentration of VFAs were accomplished by a slight fractionation of acids with respect to the initial solution; the main outcome of which was an enrichment of acetate in the concentrate. Transport of each acidic anion across the membranes was affected by the concomitant role of concentration and diffusivity, which can shift the natural order imposed by the steric hindrance of the species.
The present work was dedicated to verify the possibility of producing polyhydroxyalkanoates (PHAs... more The present work was dedicated to verify the possibility of producing polyhydroxyalkanoates (PHAs) by using a pure culture of Cupriavidus necator with a volatile fatty acids (VFAs)-rich, anaerobically digested olive mill waste water (OMWacid). To this aim, two experiments were carried out in 500-mL Erlenmeyer flasks (working volume: 150 mL). In the first one, the fermentation was divided into two sequential phases: a balanced growth phase, dedicated to biomass accumulation within a mineral medium (E2) containing glucose and fructose (2.5 g/L each); and a storage phase, carried out by replacing the culture medium with a nitrogen limiting one containing VFAs as the carbon source. The latter medium was prepared by mixing OMWacid with ammonia-free E2 in the ratio 100, 75, 50 and 25%. The total VFAs concentration in OMWacid was about 10 g/L (acetic, butyric and propionic acids concentrations: 7, 1.8 and 1.3 g/L, respectively). First results showed a higher polymer production by employing...
Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform ch... more Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform chemicals. However, the major challenges in this fermentation are limited product yields and productivities faced due to product inhibition and difficulty in carboxylate separation and recovery from fermentation broths. To mitigate the above problems, process optimization via integrated fermentation-separation i.e. in-situ product recovery (ISPR) systems can be considered. As a first step towards development of such coupled carboxylate bioprocesses, this study aimed to provide a detailed analysis of extraction behaviour of a wide array of extractants and diluents for C2-C6 carboxylates in synthetic solutions and real effluent from acidogenic fermentation. Compared to physical extraction without extractant, a 75-85% increase was achieved when using reactive extraction (RE) and the difference was more pronounced for short chain carboxylates, particularly at pH 4.5. Distribution coefficients and extraction efficiencies increased with increasing extractant concentration and reached an equilibrium at molar ratio of 1:2. Aliquat 336 and tri-octylphosphine oxide solved in methyloctanoate emerged as the best RE systems and yielded high extraction efficiencies of 11.5 and 29.5 (acetic acid) to almost 100 (caproic acid) respectively. Testing with real fermentation effluent demonstrated similar high extraction yields as observed on synthetic solutions. Potential toxicity of RE on acidogenic fermentation was also investigated which suggested the application of an external ISPR configuration for these coupled bioprocesses.
Environmental Engineering and Management Journal, 2013
Pesticides can be considered useful to eliminate pests, but can also induce negative effects to t... more Pesticides can be considered useful to eliminate pests, but can also induce negative effects to the processes of germination, growth and development of plants or disrupt some physiological and metabolic processes. By studying the effect of pesticides on treated seeds germination, and determination of growth indices, it was possible to evaluate the positive or negative influence or toxicity of the chemical compounds. The aim of this research is to highlight the effects of differentiated treatment with two types of pesticides with their common name Actara 25 WG and Topsin AL 70 PU on germination, growth and development of wheat plantlets. The experiment included 1300 wheat seeds which were divided into thirteen groups, the first group of 100 wheat seeds was considered the control sample and the others were divided equally into twelve groups which were treated with three different concentration dose of each pesticide, one less, one optimal, and one more compared to the optimal one for treatment, acting for a period of 14 and 24 hours. Biometric examinations of seedlings were subjected to analysis of variance (ANOVA) followed by Tukey's B test and analysis of covariance (ANCOVA). The concentration of each pesticides and acting time may also influence the allometric relationship between stem weights and stem length, root weight and number of roots, in different ways. It was observed the existence of a relationship between pesticides concentration, exposure time and weight of steam, in case of Topsin fungicide, under the influence of steam length, the observed power of this dependence being very high, 0.975.
The production of oxygenated bio-additives for traditional fuels represents a key challenge due t... more The production of oxygenated bio-additives for traditional fuels represents a key challenge due to their depletion in the near-future and their positive contribution to the reduction in environmental pollution. The present study considers the synthesis of 1-hexanol/hexyl hexanoate mixtures, two oxygenated Diesel bio-additives produced through the hydrogenation of hexanoic acid, obtainable from the fermentation of a wide variety of waste biomasses. In our case, crude hexanoic acid was produced through the fermentation of grape pomace, an abundant Italian agrifood waste. Commercial 5 wt% Re/γ-Al2O3 was adopted for the catalytic hydrogenation of crude hexanoic acid, and the support acidity allowed the tuning of the reaction selectivity toward the formation of hexyl hexanoate, instead of 1-hexanol, reaching yields of 40 and 25 mol%, respectively. The effects of each bio-additive on Diesel engine performance and exhaust emissions (soot, nitrogen oxides, carbon monoxide, unburned hydrocar...
The transition from fossil resources to renewable ones represents a pressing need. The acidogenic... more The transition from fossil resources to renewable ones represents a pressing need. The acidogenic fermentation of biomass-derived ethanol to carboxylic acids represents a novel and smart possibility, opening the way for the production of further value-added bio-products through cascade chemical approaches. In this work, the hydrogenation of commercial hexanoic acid to give 1-hexanol/hexyl hexanoate mixtures was preliminary studied in the presence of commercial rhenium catalysts (Re2O7 and 5 wt% Re/C), which resulted as mainly active and selective towards 1-hexanol. On the other hand, the use of niobium phosphate as the acid co-catalyst markedly shifted the selectivity towards hexyl hexanoate. Moreover, 5 wt% Re/C and physical mixtures of (5 wt% Re/C + niobium phosphate) were further tested for the hydrogenation of crude hexanoic acid obtained through fermentation of white grape pomace, confirming the promising performance of these catalytic systems and their recyclability. For the f...
Biorefinery has been defined as the sustainable conversion of biomass towards a spectrum of bioba... more Biorefinery has been defined as the sustainable conversion of biomass towards a spectrum of biobased products for different industrial fields, among which the food and feed, chemical, and energetic sectors. This concept was assessed at the beginning of the century and it was initially related to biofuels production through processing of dedicated biomass, i.e., sugar or oleaginous crops specifically cultivated for bioethanol and biodiesel production, respectively. Despite the consequent development of strategies for culture intensification, biofuel costs have not been competitive when compared with fossil-based counterparts. Low energy product values have contributed to this evidence; furthermore, with respect to conventional refinery fed with fossil sources, biofuel production needs to face up to higher costs associated with related raw materials, due to the facts that they are typically seasonal, widely distributed in larger territories, complex and variable in composition.
Environmental Engineering and Management Journal, 2013
A large variety of agro-wastes are actually investigated for their reliability as renewable sourc... more A large variety of agro-wastes are actually investigated for their reliability as renewable sources: the possibility to employ some organic residues for the production of biomolecules, biofuels and biomaterials has fostered the born of the concept of second generation biorefineries, which differ from the first generation processes, since non dedicated crops are used as the feedstock. To this aim, Olive Mill Wastewaters (OMWs) are the most investigated wastes, due to their high organic content and to a high concentration of polyphenols, compounds that are natural antioxidant. If on the one hand OMWs are recalcitrant to biodegradation and their environmental impact can represent a serious issue, on the other hand these wastes show a biochemically interesting composition, rich of sugars, lipids, alcohols and organic acids. Recent studies have demonstrated that a lot of processes can be applied to OMWs, which can be exploited for the recovery of polyphenols, production of biofuels or ch...
Environmental Engineering and Management Journal, 2013
1 DICAM, University of Bologna, via Terracini 28, I-40131, Bologna, Italy 2 Eridania Sadam S.p.A,... more 1 DICAM, University of Bologna, via Terracini 28, I-40131, Bologna, Italy 2 Eridania Sadam S.p.A, Via degli Agresti 4/6, I-40123, Bologna, Italy 3 Sebigas S.p.A., Via Santa Rita, 21057, Olgiate Olona (VA), Italy 4 Sadam Engineering s.r.l., Via degli Agresti 4/6, I-40123, Bologna, Italy Stefano Rebecchi1, Lorenzo Bertin1, Veronica Vallini2, Giacomo Bucchi3, Fabrizio Bartocci4, Fabio Fava1 Rimini, 7 Novembre 2013
Biogas upgrading from anaerobic digestion of waste frying oils (WFO) was accessed in this study. ... more Biogas upgrading from anaerobic digestion of waste frying oils (WFO) was accessed in this study. For that, two bioreactors (Rb-biogas-lift bioreactor with gas and liquid recirculation, Rc-control reactor with liquid recirculation) were fed three times per week, with a mixture of WFO, glycerol and volatile fatty acids (VFA). Rb produced 1.4 times more biogas with higher methane content (79%) than Rc (67%). Higher relative abundance of hydrogenotrophic methanogens (34%e39%) was observed in Rb, when compared to Rc (16%e21%). The relative abundance of Sprochaetia class, which includes some homoacetogens/ syntrophic acetate oxidizing genera, was also higher in Rb. This work shows that biogas recirculation applied in the biogas-lift bioreactor facilitated WFO degradation, most probably due to the selective enrichment of hydrogenotrophic methanogens. Recirculation of CO 2 present in the biogas and reverse homoacetogenesis (i.e. syntrophic acetate oxidation) seem to be the main factors involved in the stimulation of hydrogenotrophic methanogenesis.
Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform ch... more Biorefinery wastewaters can be fermented to produce carboxylates which are high-value platform chemicals. However, the major challenges in this fermentation are limited product yields and productivities faced due to product inhibition and difficulty in carboxylate separation and recovery from fermentation broths. To mitigate the above problems, process optimization via integrated fermentation-separation i.e. in-situ product recovery (ISPR) systems can be considered. As a first step towards development of such coupled carboxylate bioprocesses, this study aimed to provide a detailed analysis of extraction behaviour of a wide array of extractants and diluents for C2-C6 carboxylates in synthetic solutions and real effluent from acidogenic fermentation. Compared to physical extraction without extractant, a 75-85% increase was achieved when using reactive extraction (RE) and the difference was more pronounced for short chain carboxylates, particularly at pH 4.5. Distribution coefficients and extraction efficiencies increased with increasing extractant concentration and reached an equilibrium at molar ratio of 1:2. Aliquat 336 and tri-octylphosphine oxide solved in methyloctanoate emerged as the best RE systems and yielded high extraction efficiencies of 11.5 and 29.5 (acetic acid) to almost 100 (caproic acid) respectively. Testing with real fermentation effluent demonstrated similar high extraction yields as observed on synthetic solutions. Potential toxicity of RE on acidogenic fermentation was also investigated which suggested the application of an external ISPR configuration for these coupled bioprocesses.
Wastewater reclamation and reuse became essential to meet the more restrictive discharge limits a... more Wastewater reclamation and reuse became essential to meet the more restrictive discharge limits and to overcome the water scarcity issue. Industrial wastewaters treated by membrane bioreactor (MBR) systems generally include high amounts of salinity, nutrients as nitrogen and phosphorus, heavy metals, hardness, etc. which in most cases, do not fit with discharge and reuse limits. Membrane processes like nanofiltration (NF) and reverse osmosis (RO) are widely adopted for secondary effluent treatment producing high-quality water. Since untreated brine can damage the environment, this work focused on reduction of amount of concentrate by working in membrane-in-series configuration. Tests with two membrane-in-series (NF90+NF90, BW30+BW30, BW30+NF270 combinations) were performed as the concentrate stream of the first one was fed to the second one. Water recoveries were over 80% in each experiment. Water fluxes of 44.0, 41.4 and 73.4 L/m 2 .h were obtained with NF90+NF90, BW30+BW30, BW30+NF270 combinations, respectively. Also, salinity rejections represented by electrical conductivity were 93.0%, 97.4% and 42.4% for NF90+NF90, BW30+BW30, BW30+NF270 configurations, respectively. Permeates of BW30+BW30 and NF90+NF90 combinations seem to be useable for agricultural irrigation although soil permeability is an important issue, not only ion concentrations and salinity of water used.
Clean water sources are quickly depleted since the industrial revolution due to climate change an... more Clean water sources are quickly depleted since the industrial revolution due to climate change and overpopulation. Use of potable water for agricultural irrigation is under imminent threat. Therefore, it is important to obtain irrigation water from alternative sources such as industrial wastewaters. On the other hand, industrial wastewaters have to be treated well otherwise they can pollute the environment and decrease the irrigation potential of soil. Membrane bioreactor (MBR) effluents of industrial wastewaters have a great potential to be used in agricultural irrigation. In this study, the permeates of NF270 and BW30-RO membranes were produced from MBR effluent discharged from Wastewater Treatment Plant of ITOB Organized Industrial Zone, Menderes, Izmir. They were evaluated for their reuse in agricultural irrigation. While doing this evaluation, effect of operating pressure on water quality was also investigated. It was found that the RO permeate is not suitable to reuse in irrigation. On the other hand, the NF permeate could be suitable for medium-salinity tolerant plants.
Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed ... more Volatile fatty acids (VFAs) were produced using cheese whey as feedstock. A mixed culture packed bed bioreactor was set-up to digest anaerobically under acidogenic condition a water solution of a cheese whey powder. Batch tests pointed out that the whole VFAs production process occurred via two sequential phases: (a) conversion of lactose into lactic acid; (b) conversion of lactic acid into a mixture of VFAs. Furthermore, the same tests showed that the ceramic material Vukopor S10 can be used as an effective support for cell immobilization in anaerobic fermentation processes. The effect of the hydraulic retention time (HRT) and organic loading rate (OLR) were then studied in a bench-top bioreactor operated continuously. By a HRT of 6 days, OLR of 25 glactose.L -1 .d -1 and pH 5.8-6, 16 g.L -1 of total VFAs were produced, with a yield higher than 75% (CmolVFAs.Cmollactose -1 ). Characterization with Illumina-based sequencing suggested that high VFAs productivities were obtained when microbial community structures developed in the biofilm reactor were highly enriched in few genera.
International Journal of Chemical Engineering, 2016
The goals of this work were (i) to compare two anion ion exchange resins (IRA958 Cl and IRA67) an... more The goals of this work were (i) to compare two anion ion exchange resins (IRA958 Cl and IRA67) and a nonionic resin (XAD16) in terms of phenolic compounds adsorption capacity from olive mill wastewater and (ii) to compare the adsorption capacity of the best resin on columns of different length. The ion exchange resins performed worse than nonionic XAD16 in terms of resin utilization efficiency (20% versus 43%) and phenolic compounds/COD enrichment factor (1.0 versus 2.5). The addition of volatile fatty acids did not hinder phenolic compounds adsorption on either resin, suggesting a noncompetitive adsorption mechanism. A pH increase from 4.9 to 7.2 did not affect the result of this comparison. For the best performing resin (XAD16), an increase in column length from 0.5 to 1.8 m determined an increase in resin utilization efficiency (from 12% to 43%), resin productivity (from 3.4 to 7.6 gsorbed phenolics/kgresin), and phenolics/COD enrichment factor (from 1.2 to 2.5). An axial disper...
Rotating Algal Biofilm Reactor (RABR) technology was successfully employed in an effective strate... more Rotating Algal Biofilm Reactor (RABR) technology was successfully employed in an effective strategy to couple the removal of wastewater nutrients with accumulation of valuable bioproducts by grown algae. A secondary stage municipal wastewater was fed to the developed system and the effects of the hydraulic retention time (HRT) parameter on both nutrient removal and bioproduct production were evaluated under fed-batch operation mode. Two sets of bench scale RABRs were designed and operated with HRTs of 2 and 6 days in order to provide competitive environment for algal growth. The HRT significantly affected nitrogen and phosphorus uptakes along with lipid and starch accumulations by microalgae in harvested biofilms. Domination of nitrogen removal in 2-day HRT with higher lipid accumulation (20% on dried weight basis) and phosphorus removal in 6-day HRT with higher starch production (27% on dried weight basis) was observed by comparing the performances of the RABRs in duplicate runs.
Electrodialysis (ED) is applied for the first time as a separation-concentration step of the Vola... more Electrodialysis (ED) is applied for the first time as a separation-concentration step of the Volatile Fatty Acids (VFAs) enriched effluent resulting from fermentation of olive mill wastewaters. The process would represent a key step of an integrated multi-purpose biorefinery scheme including the biotechnological production of polyhydroxyalkanoates from acidified bioresidues. A feasibility study is introduced by testing separation efficiency of membranes with synthetic model solutions of different compositions (sodium acetate and NaCl, or acetic-propionic-butyric acids with NaCl) and with actual OMW (a complex mixture of sodium salts of acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic, caproic, eptanoic acids, NaCl and other electrolytes). Experiments were performed at room temperature in a lab-scale 2-compartments ED stack, containing Neosepta AMX-CMX membranes, at constant current density (31 A/m 2 ). Membrane resistance was tested by performing additional ED experiments according to a proper protocol developed in this work. Removal of VFAs from actual OMW is feasible; no evidence of remarkable damages nor losses of membrane performance were observed after dedicated trials. Under the operative conditions investigated, VFAs removals ranged from 30 to 35%, resulting in a concentration factor between 1.2 and 1.5 with respect to the initial mother solution. Chloride removal was remarkably high and it was greatly favoured at the beginning of operation; competition between chloride and acidic anions was remarkable as far as chloride concentration was high, whereas acidic anions transport across the membrane increased after NaCl removal overcame 50%. Removal and concomitant concentration of VFAs were accomplished by a slight fractionation of acids with respect to the initial solution; the main outcome of which was an enrichment of acetate in the concentrate. Transport of each acidic anion across the membranes was affected by the concomitant role of concentration and diffusivity, which can shift the natural order imposed by the steric hindrance of the species.
The present work was dedicated to verify the possibility of producing polyhydroxyalkanoates (PHAs... more The present work was dedicated to verify the possibility of producing polyhydroxyalkanoates (PHAs) by using a pure culture of Cupriavidus necator with a volatile fatty acids (VFAs)-rich, anaerobically digested olive mill waste water (OMWacid). To this aim, two experiments were carried out in 500-mL Erlenmeyer flasks (working volume: 150 mL). In the first one, the fermentation was divided into two sequential phases: a balanced growth phase, dedicated to biomass accumulation within a mineral medium (E2) containing glucose and fructose (2.5 g/L each); and a storage phase, carried out by replacing the culture medium with a nitrogen limiting one containing VFAs as the carbon source. The latter medium was prepared by mixing OMWacid with ammonia-free E2 in the ratio 100, 75, 50 and 25%. The total VFAs concentration in OMWacid was about 10 g/L (acetic, butyric and propionic acids concentrations: 7, 1.8 and 1.3 g/L, respectively). First results showed a higher polymer production by employing...
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