The application of different techniques to determine activated sludge kinetic parameters in a food industry wastewater

In the present work, a continuous-feed system under steady state conditions (classical method) and a respirometric technique based on oxygen consumption measurements, were used to compare microbial parameters using a wastewater model system of a potato processing plant. The effects of the operating conditions in the continuous aerobic reactor on microbial growth and flora composition were also analysed. Continuous-feed experiments allowed for the calculation of the following biodegradation parameters: maximum substrate consumption specific rate (qSmax) = 0.19 mgCOD (mgVSS)-1·h-1, saturation constant (Ks) = 8.3 mgCOD·l-1, biomass yield (YX/S) = 0.61 mgVSS (mgCOD)-1, biomass decay constant (kd) = 0.04·h-1 and maximum oxygen consumption specific rate (qO2max) = 0.03 mgCOD (mgVSS)-1·h-1.The respirometric technique also allowed for the calculation of kinetic parameters. However, these parameters depended on dilution rate (D) and / or on dissolved oxygen concentration (DO). Values of qO2max and Ks increased with D; qO2max ranged between 0.05 and 0.13 mgO2 (mgVSS)-1·h-1 and Ks between 2 and 26 mgCOD·ℓ-1 for D values varying between 0.01 and 0.15·h-1. Microscope observations showed that sludge composition was a function of dilution rate. Low D values (low soluble organic matter (Ss) and high DO concentrations) yielded sludges mainly formed by floc-forming bacteria; high D values (high Ss and low DO concentrations) yielded sludges mainly formed by filamentous micro-organisms. Since the low substrate / biomass ratios used in the respirometric method limit the growth of micro-organisms maintaining the initial physiological state of the original biomass, the observed differences in the respirometric parameters reflected the actual microbial composition.Fil: Contreras, Edgardo Martin. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Bertola, Nora Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería; ArgentinaFil: Zaritzky, Noemi Elisabet. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería; Argentin

Kinetic characterization of digestive proteinases extracted from the processing waste of South Atlantic fish

In Argentina, the fishing industry is highly developed, producing large quantities of waste products from fish processing which contain digestive enzymes with potential biotechnological uses. Among these enzymes are proteinases that hydrolyze proteins and can convert them into functional ingredients. To use these value-added compounds in industrial processes, kinetic characterization of these proteinases under specific conditions, such as contact time, pH, and temperature, must first be carried out. The objective of the present work was to perform a kinetic characterization of crude extracts of alkaline proteinases from intestine-ceca of Merluccius hubbsi, Percophis brasiliensis, Urophycis brasiliensis, and Cynoscion guatucupa. Results showed that the reached maximum values of A440 depended on both the species analyzed and the initial concentration of azocasein. The maximum concentration of hydrolysis products obtained at long times was proportional to the initial concentration of the target protein. P. brasiliensis was the most suitable tested species to obtain high hydrolysis rates at high azocasein concentrations, and exhibited the highest proteinase activities, so it can be considered a candidate species for future biotechnological applications.Fil: Friedman, Ivana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Fernandez Gimenez, Analia Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Orange II removal by a horseradish peroxidase immobilized onto chemically modified diatomites is a combination of adsorption and oxidation processes

In this work, a horseradish peroxidase (HRP) was immobilized onto diatomites by covalent bonding. Results indicated that the enzyme loading increased when diatomites were modified with (3-Aminopropyl) triethoxysilane (APTES) and glutaraldehyde. The immobilization was confirmed by SEM/EDX, XRD, DRIFT, and TGA analysis. Higher HRP concentrations of the immobilization solution and immobilization time had also a positive effect on the enzyme loading. Orange II (OII) adsorption onto diatomites and oxidative catalytic activity was evaluated. Results demonstrated that diatomites had a low OII adsorption capacity. However, under the presence of hydrogen peroxide, the dye removal was highly increased due to the catalytic activity of the immobilized HRP. A mathematical model that adequately describes the simultaneous adsorption and enzymatic oxidation of OII in batch tests was developed. Finally, immobilized diatomites were tested in the decolourization reaction of Orange II in a fixed-bed column reactor. Column results demonstrated that the immobilized HRP remained active for at least 12 h during three sequential OII removal tests.Fil: Morales Urrea, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química; ArgentinaFil: Haure, Patricia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química; ArgentinaFil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Simultaneous biodegradation of bisphenol A and a biogenic substrate in semi-continuous activated sludge reactors

In this work, the simultaneous degradation of BPA and cheese whey (CW) in semi-continuous activated sludge reactors was studied. The acclimation process and microbial growth on BPA, CW and BPA + CW were analyzed. In addition, the effect of increasing CW concentration on the BPA degradation by acclimated activated sludge was also studied. In order to reduce the factors involved in the analysis of the simultaneous degradation of BPA and CW, the effect of bisphenol A (BPA) on activated sludge not previously exposed to BPA (native activated sludge) was studied. Results demonstrate that BPA concentrations lower than 40 mg l−1 had a negligible effect on the growth of native activated sludge. In the semi-continuous reactors, the presence of CW increased the acclimation time to 40 mg l−1 of BPA. Once the capability of degrading BPA was acquired, the removal of BPA was not affected by the presence of CW. Increasing the CW concentration did not affect the removal of BPA by the acclimated activated sludge. Additionally, the CW consumption was not modified by the presence of BPA. Kinetic and stoichiometric coefficients reported in the present work can be useful in developing mathematical models to describe the simultaneous aerobic biodegradation of a biogenic substrate, such as CW, and BPA by activated sludge.Fil: Ferro Orozco, Ana Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Zaritzky, Noemi Elisabet. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin

Potato pulp as a biomaterial to remove an industrial pollutant compound (Orange II)

En el presente estudio se acondicionó un biomaterial a base de pulpa de papa liofilizada (PPL) para la remoción de un colorante industrial, Orange II (S), con peróxido de hidrógeno (P). El uso de enzimas es actualmente una de las tecnologías más promisorias para la eliminación de contaminantes industriales recalcitrantes. Se caracteriza la actividad peroxidasa de PPL mediante la oxidación de ácido 2,2´-azino-bis-(3-etillbenzotiazolin-6-sulfónico) (ABTS) y su capacidad para remover S. Los resultados indicaron que PPL es una potencial fuente de enzima peroxidasa y que además tiene la capacidad para eliminar el Orange II mediante oxidación enzimática y bioadsorción. Esto aporta la catálisis enzimática, un 65 % de la remoción total del colorante. Se concluye que la decoloración de S con P en presencia de PPL es conveniente realizarla a pH 9 y un valor inicial de P0/S0 = 10 mol/mol.In the present research study, a biomaterial from lyophilized potato pulp (PPL) was developed to remove a common industrial dye (Orange II, S) with hydrogen peroxide (P). Enzymatic catalysis is one of the most promising technologies to eliminate recalcitrant industrial compounds. Peroxidase activity of PPL is characterized by oxidation of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate acid (ABTS) and its ability to remove S. The results indicated that PPL was a potential source of peroxidase enzymes that can also remove Orange II by enzymatic oxidation and bioadsorption. The enzymatic process contributed to close to 65 % of the total dye removal. It is concluded that S decolourization with P by PPL was best at pH 9 and with an initial value of P0/S0 = 10 mol/mol.Fil: Morales Urrea, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: López Córdoba, Alex Fernando. Universidad Pedagógica y Tecnológica de Colombia; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Inactivation of a commercial peroxidase by hydrogen peroxide

El objetivo del presente trabajo fue evaluar la estabilidad de una peroxidasa comercial (HRP) en condiciones de reacción. Espectrofotométricamente se pudieron identificar tres estados de la enzima. En ausencia de peróxido (P), la enzima está en su estado basal (E0). Aunque la literatura indica que en presencia de P el estado basal E0 se oxida a un estado E1 perdiendo dos electrones, solo se observó el estado intermedio E2, el cual está un electrón debajo de E0. En presencia altas concentraciones de P se identificó una tercera especie E3, la cual decae a E0. Además, la HRP pudo catalizar la descomposición del peróxido, evidenciando la actividad catalásica de la HRP. El decaimiento de E3 también generó una especie Ex, la cual resultó catalíticamente inactiva. Asimismo, la formación de la especie inactiva se correlacionó con la pérdida de actividad peroxidasa. Experimentos similares en presencia de OII como sustrato reductor externo, empleando bajas concentraciones de P y tiempos cortos, muestran también una disminución de la actividad peroxidasa. Considerando que en estas condiciones la formación de E3 es despreciable, los resultados sugieren una ruta alternativa de inactivación, independiente de la formación de E3. Por lo tanto, se concluye que en las condiciones estudiadas la pérdida de actividad enzimática es una característica intrínseca de la HRP estudiada.The objective of the present work was to evaluate the stability of a commercial peroxidase (HRP) under reaction conditions. Three states of the enzyme could be identified spectrophotometrically. In the absence of peroxide (P), the enzyme is under its basal state (E0). Although the literature indicates that the ground state E0 can be readily oxidized by P to a state E1 losing two electrons, only the intermediate state E2 was observed, which is one electron below E0. In the presence of high concentrations of P, a third species E3 was identified, which slowly decays to E0. Furthermore, HRP was able to catalyze the decomposition of peroxide, demonatrating the catalasic activity of HRP. The decay of E3 also generated a species Ex, which was catalytically inactive. Likewise, the formation of the inactive species was correlated with the loss of peroxidase activity. Experiments in the presence of OII as an external reducing substrate, using low concentrations of P and short times, also show a decrease in peroxidase activity. Considering that under these conditions the formation of E3 is negligible, results suggest an alternative inactivation pathway, independent of the formation of E3. Therefore, it is concluded that in the studied conditions the loss of enzymatic activity is an intrinsic characteristic of the studied HRP.Fil: Morales Urrea, Diego Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

Carbon dioxide stripping in bubbled columns

The carbonate buffer system plays a fundamental role in the biological treatments of wastewaters. In this work, the CO2 volumetric mass transfer coefficient (kLac) in a bubbled column was determined using the conventional titration method for different column volumes and air flow rates. In addition, a simple method to determine k Lac based on the interpretation of the changes in the pH level due to the CO2 stripping was developed. Results show that the apparent CO2 volumetric mass transfer coefficient (k Lac-app was strongly affected by the pH level; however, the actual CO2 volumetric mass transfer coefficient, k Lac = kLac-app/aα 0«, was constant within the tested pH conditions. In addition, kLac increased with higher air flow rates and lower column volumes; the obtained kLac values ranged between 20.0 and 71,9 h-1. For all the tested conditions, kLac values obtained using the noncontrolled pH method were similar to the values measured using the titrimetric method. The proposed mathematical model represented adequately the changes on the pH level and total inorganic carbon species concentration as a function of time. The model was extended to take into account the effect of phosphates. Simulation results showed that, although phosphates buffered the changes of pH, the losses of total inorganic carbon were faster than in the case of a nonbuffered solution; thus, the rise in the pH level prevented the stripping of CO2.Fil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

COD/DOC balanced models for the oxidation process of organic compounds

Nowadays, several advanced oxidation and enzymatic processes are available for the removal of organic compounds. Mathematical models are crucial to optimize the operating conditions and to reduce the costs associated with the studied oxidation process. The present work deals with a procedure to develop COD/DOC balanced models to represent the oxidation process of organic compounds. The procedure is of general nature since no hypothesis is made regarding the identity of the organic compounds or the oxidant employed. Using the developed procedure, proposed oxidation pathways always fulfill elemental and electron balances. Several examples of oxidation pathways were studied to demonstrate the usefulness of the procedure. From the analysis of a particular pathway, several restrictions regarding the range of possible values of the model coefficients can be found. These restrictions can be used to enhance the robustness of the fitting procedure of the model by using different types of data, such as COD, DOC and/or the actual concentration of some relevant species. This work will help researchers in areas related to the removal of organic compounds using any oxidation process.Fil: Contreras, Edgardo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin