Firmness and Gentleness in the Spirituality of Father Francis Libermann

https://dsc.duq.edu/libermann-collection/1033/thumbnail.jp

Role and variations of supernatant compounds in submerged membrane bioreactor fouling

Many studies have been performed to analyze the influence of extracellular polymeric substances (EPS) in membrane fouling. Most of these works deal with the impact of solid contents in the fouling, and some of them have studied the role ofsupematant compounds. The aim of this work was to clarify the role of the different sludge fractions in the context of membrane bioreactor fouling. The laboratory-scale reactor used for experiments consists of a submerged membrane bioreactor for the treatment of synthetic wastewater. For the same organic load (0.4 g COD/g MLSS.d), several samples of sludge were taken off and divided intohree fractions (solid contents, soluble and colloids). COD and extractable EPS were quantified (carbohydrates and proteins). Dead-end filtration tests for each fraction were also carried out. According to these experiments, no correlation between EPS concentration in the solid part of the sludge and filtration resistance was found. Instead, a change of the filtration resistance was explained as a function of COD in the supematant, and more especially as a function of proteins concentration. Indeed, when the value of proteins concentration in the supernatant changes from 30 to 100 mg/1, the value of specific resistance increased by a factor of 10. Finally, the characterization of the supematant was shown as a key parameter for the MBR operating control. When the COD and proteins concentration in the supematant remained low, the transmembrane pressure in the reactor remained even lower. Moreover, with the biomass growth rate analysis, our results suggest that the EPS production was linked to growth of microorganisms. The faster he growth, the less EPS production

Rheological characterization of mixed liquor in a submerged membrane bioreactor: Interest for process management

Rheological analyses of a submerged membrane bioreactor mixed liquor were performed in the aim of characterizing the mixed liquor present in the bioreactor and thus proposing a process management. These analyses pointed out that the mixed liquor was characterized by its viscoplastic property, which leads to a possible restructuring ability when a shear stress lower than the yield stress is applied. As the shear stress in the bioreactor is essentially generated by coarse bubbles, specific experiments were carried out in which coarse bubbles were injected in an intermittent way. The results of these experiments showed that this method could avoid damage to the mixed liquor. So working with intermittent coarse bubbles is useful to prevent fouling, keep good flocculation and minimize the energy cost

Aeration mode, shear stress and sludge rheology in a submerged membrane bioreactor: some keys of energy saving

Aeration mode, shear stress and sludge rheology in a submerged membrane bioreactor: some keys of energy savin

Effect of weather conditions on somatic cell score in Sicilian Valle del Belice ewes

Mastitis susceptibility of Valle del Belice ewes from the south of Sicily to temperature, humidity, precipitation, solar radiation, sun hours, air pressure, wind-speed and wind-direction measured by a public weather station was investigated using 65,848 test-day somatic cell score (SCS) records of 5,237 ewes. All weather parameters had an effect on SCS in a regression approach. Extreme values of maximum and minimum temperaturehumidity indices resulted in increased SCS. Higher precipitation, solar radiation and sun hours resulted in increased SCS, whereas higher air pressure and wind speed resulted in reduced SCS

Genetic parameters for milk somatic cell score and relationships with production traits in primiparous dairy sheep

A total of 13,066 first-lactation test-day records of 2,277 Valle del Belice ewes from 17 flocks were used to estimate genetic parameters for somatic cell scores (SCS) and milk production traits, using a repeatability test-day animal model. Heritability estimates were low and ranged from 0.09 to 0.14 for milk, fat, and protein yields, and contents. For SCS, the heritability of 0.14 was relatively high. The repeatabilities were moderate and ranged from 0.29 to 0.47 for milk production traits. The repeatability for SCS was 0.36. Flock-test-day explained a large proportion of the variation for milk production traits, but it did not have a big effect on SCS. The genetic correlations of fat and protein yields with fat and protein percentages were positive and high,indicating a strong association between these traits. The genetic correlations of milk production traits with SCS were positive and ranged from 0.16 to 0.31. The results showed that SCS is a heritable trait in Valle del Belice sheep and that single-trait selection for increased milk production will also increase SCS

Hoe hoort het bij een invorderingsbeschikking?

Dat de geadresseerde van een last onder dwangsom wordt gehoord voordat het bestuursorgaan het besluit oplegt, is gelet op artikel 4:8 Awb een juridisch vereiste. Daarentegen wordt – als de last wordt overtreden – de (ambtshalve) invorderingsbeschikking zonder enige vorm van horen genomen, onder verwijzing naar artikel 4:12 Awb. Is dit wel terecht of is er aanleiding om de geadresseerde toch te horen? Die is er inderdaad en de jurisprudentie waarin ervan wordt uitgegaan dat artikel 4:12 Awb van toepassing is op invorderingsbeschikkingen is toe aan herziening. Dat wordt in dit artikel betoogd. The Legitimacy and Effectiveness of Law & Governance in a World of Multilevel Jurisdiction

Firmness and Gentleness In The Spirituality of Father Francis Libermann

https://dsc.duq.edu/libermann-collection/1033/thumbnail.jp

Bioréacteur à membranes immergées pour le traitement d’eaux usées domestiques. Influence des conditions de filtration et de l’hydrodynamique sur les performances du procédé.

Le travail présenté dans ce mémoire est focalisé sur la compréhension de l’action des paramètres de filtration (temps de filtration, de non filtration, de rétrolavage, mode et débit d’aération) dans un BAMI pour le traitement d’eaux usées domestiques. La partie expérimentale a été conduite en deux temps. Tout d’abord sur effluent synthétique pour tester différentes conditions opératoires de filtration dans des conditions biologiques maîtrisées puis sur effluent domestique afin de valider les expériences précédentes. Les résultats de ces expérimentations ont mis en évidence que : - Le temps de non filtration pouvait être optimisé à partir de valeurs seuil de la perméabilité de la membrane et de la résistance spécifique de la liqueur mixte. - l’antagonisme dans le rôle de l’aération. D’une part un train de grosses bulles vient classiquement limiter l’apport de matière à la membrane (décolmatage) et d’autre part cette aération induit un cisaillement déstructurant les flocs (colmatage). Une caractérisation hydrodynamique et rhéologique du système a montré le caractère viscoplastique de la boue de BAMI et la pertinence de l’aération syncopé lors de la filtration d’un tel fluide. - L’ensemble des expériences menées sur l’effluent réel a confirmé d’une part les conditions opératoires choisies, d’autre part les caractéristiques de la boue sous contrainte de cisaillement. - L’analyse technico-économique, qui tient compte du « remplacement » des membranes pour lavage montre que l’on a mis en évidence des plages de paramètres opératoires conduisant à un fonctionnement rentable du procédé de traitement d’eau résiduaire urbaine. ABSTRACT : The aim of this work is the study of a waste water treatment operation using a submerged membrane bioreactor. The study was focused on the influence of operating parameter (filtration time, non filtration time, backflushing, aeration mode and aeration flow rate) in the prevention of membrane fouling. The first part of the study was made with synthetic effluent in order to test several filtration operating conditions in a well known biological environment. The second part consisted in the test of the system with municipal wastewater in order to validate the previous experiments. The main results are that : - Non filtration time can be optimized according to threshold value for membrane permeability and mixed liquor specific resistance. - Aeration has an opposite influence. On one hand, coarse bubbles are useful to prevent membrane fouling but on the other hand aeration can disturb sludge flocculation. Rheological and hydrodynamic analyses points out the viscoplasticity of the mixed liquor, which increases the interest in injecting coarse bubbles in an intermittent way. - Experiments realized with domestic effluent confirm on one hand the operating parameter choice and on the other hand sludge rheological characteristics. - Energetic analysis have pointed out that the operating parameters fixed in this study leads to an economically viable process for domestic wastewater