A General Approach for Predicting the Filtration of Soft and Permeable Colloids: The Milk Example

Membrane filtration operations (ultra-, microfiltration) are now extensively used for concentrating or separating an ever-growing variety of colloidal dispersions. However, the phenomena that determine the efficiency of these operations are not yet fully understood. This is especially the case when dealing with colloids that are soft, deformable, and permeable. In this paper, we propose a methodology for building a model that is able to predict the performance (flux, concentration profiles) of the filtration of such objects in relation with the operating conditions. This is done by focusing on the case of milk filtration, all experiments being performed with dispersions of milk casein micelles, which are sort of ″natural″ colloidal microgels. Using this example, we develop the general idea that a filtration model can always be built for a given colloidal dispersion as long as this dispersion has been characterized in terms of osmotic pressure Π and hydraulic permeability k. For soft and permeable colloids, the major issue is that the permeability k cannot be assessed in a trivial way like in the case for hard-sphere colloids. To get around this difficulty, we follow two distinct approaches to actually measure k: a direct approach, involving osmotic stress experiments, and a reverse-calculation approach, that consists of estimating k through well-controlled filtration experiments. The resulting filtration model is then validated against experimental measurements obtained from combined milk filtration/SAXS experiments. We also give precise examples of how the model can be used, as well as a brief discussion on the possible universality of the approach presented here

Optimal target performance for cost-effective seismic design of bridges

A systematic approach is proposed for evaluating the cost-effectiveness of existing bridge design codes from the perspective of lifecycle cost consideration. In the life cycle cost formulation, costs of construction, damage cost, road user cost, as well as discount cost over the design life of the bridge are considered. The optimal performance is selected on the basis of minimum life cycle cost. The performance of a typical two-span bridge designed according to a current code provision for different earthquake ground motion levels is predicted and optimal target performance is selected based on life cycle cost with different assumptions of user cost. It is demonstrated that life cycle cost should be considered in the design phase of a new structure or of a structure to be retrofitted, and the target performance significantly depends on the expected average daily traffic using the road

Optimal performance for cost effective seismic design of bridges

A systematic approach is proposed for evaluating the cost-effectiveness of existing design codes from the perspective of lifecycle cost consideration. In the life cycle cost formulation, cost of construction, damage cost, road user cost, as well as discount cost over the design life of the bridge are considered. The optimal performance is selected on the basis of minimum life cycle cost. The performance of a typical two-span bridge designed according to a current code provision for different earthquake ground motion levels is predicted and optimal target performance is selected based on life cycle cost with different assumptions of user cost. It is demonstrated that life cycle cost should be considered in the design phase of a new structure or of a structure to be retrofitted, and the target performance significantly depends on the expected average daily traffic for the road

Le compostage à la ferme des fumiers de dindes

In order to come up with a specification document for poultry farmers who wish to treat their poultry manure in the farm, tests have been undertaken to stress the interest of some options and to analyze the meaning of their variation. The article presents test results on swaths protected or not from atmospheric rainfalls, which have or have not been supplied water at the start, and submitted to various reversal frequencies. The thermal, physical and chemical monitorings help highlight the effects of water adjunction, which are more important than the effects of reversal frequencies on element losses (organic matter and nitrogen). Finally, the mastering of this type of treatment at the farm requires a very good knowledge of atmospheric rainfalls. / Afin d'établir un projet de cahier des charges destiné aux aviculteurs désireux de traiter leur fumier de volaille à la ferme des essais ont été entrepris pour mettre en évidence l'intérêt de certaines options et d'analyser la pertincence de leur variation. L'article présente des résultats d'expérimentations portant sur des andains protégés ou non des précipitations atmosphériques, ayant subi ou on une ajonction d'eau au départ, et sousmis à différentes fréquences de retournement. Les suivis thermiques et physico-chimiques permettent de mettre en évidence les effets plus importants de l'adjonction d'eau que des fréquences de retournement sur les pertes en différents éléments (matières organiques et azote). Enfin la maîtrise de ce type de traitement à la ferme implique une maîtrise totale des précipitations atmosphériques

Intensive livestock farming systems in use across Europe – a review of the current situation relating to IPPC based on recent data gathered by questionnaire. Final Report as the principle deliverable of Task 3 (and covering Tasks 2 relating to production of the questionnaires) EU Project BAT- Support

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [TR2_IRSTEA]TED / EPUREDetailed questionnaires were prepared covering pig and poultry production across Europe. A set of three documents were prepared, one each for the housing system for pigs and (all) poultry and a combined questionnaire covering manure handling and related water and energy consumption issues. The trio of documents with covering letter were despatched to 60 targeted specialists across the EU with at least one recipient for each of the smaller countries and up to three for the larger nations. Responses were received from all the major livestock producing nations: no replies were received from representatives from eight countries. The survey was considered valid representing over 90% of European livestock production. The amassed replies were processed and augmented with available statistical data from Eurostat to describe in detail the pig and poultry livestock industry across the EU. The analysis does not distinguish IPPC farms from smaller units but it is deemed that most of the findings address such farms these representing the larger farms which dominated the data collected. Common themes emerged to describe the housing and rearing of the main livestock types grouped as pigs and (all) poultry as defined in the IPPC directive