Documents found
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81.More information
Pig manure and landfill leachate cannot be treated only by conventional biological treatment because a "refractory" COD persists, superior to 500 mg O2.l-1 : four times too high for a direct discharge in the environment. Nanofiltration, an intermediate process between reverse osmosis and ultrafiltration, may be an interesting alternative as a final treatment. In nanofiltration, lower pressure can be used and fluxes are higher than for reverse osmosis. The present study compared the treatability of pig manure and landfill leachate after biological treatment using a pilot-scale nanofiltration plant. Performances were evaluated in terms of permeate COD and permeate flux versus operating conditions (applied pressure, crossflow velocity and recovery rate). Two tubular organic nanofiltration membranes with 450 diameter cut-offs were used for pilot-scale testing: MPT-20 (polyacrylonitrile) and MPT-31 (polysulfone). Preliminary experiments carried out at constant concentrations show that performance (permeation flux and permeate COD) depends mainly on the nanofiltration membrane/effluent coupling. Permeate fluxes obtained with the MPT-20 membrane were higher than those obtained with the MPT-31. The increased crossflow velocity produced a particularly marked flux increase for pig manure. Moreover, the flux obtained with pig manure decreased at pressures superior to 15 bars whereas for the landfill leachate it became constant regardless of the pressure applied. COD retention was better in the case of pig manure and increased with pressure. On the other hand, high crossflow velocity helped reduce the COD retention, particularly for pig manure. The difference stems mainly from the foulant layer on the membrane surface. This layer is compressible and not organised; in the case of pig manure, it may explain the influence of hydrodynamic parameters: crossflow velocity favours the back migration of potential foulant such as colloids from the membrane surface to the bulk liquid phase. This may explain an increased mass transfer and consequent reduction of COD retention at high tangential velocities. Moreover, higher pressure generates a dense layer, which leads to a reduction of mass transfer. The influence of operating conditions was less important for the leachate, as the foulant layer may be more organised and have better cohesion.In the second part of this study, the nanofiltration pilot plant was operated in concentration mode in order to evaluate the influence of recovery rate on flux and retention. Since COD retention is better with the MPT-31 membrane, the latter was used for concentration experiments. The applied pressure was fixed at 15 bar and crossflow velocity at 1.5 m.s-1. Both effluents were concentrated with a volume reduction factor of 4. However this reduction of retentate volume led to both a drop in permeation flux and a rise of permeate COD, to a value above to the environmental norm of 120 mg O2.l-1.
Keywords: Lisier de porc, lixiviat de décharge, nanofiltration, paramètres hydrodynamiques, DCO, réfractaire, Pig manure, landfill leachate, nanofiltration, hydrodynamic parameters, refractory COD
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83.More information
This paper analyzes how French regional venture capital now holds as a performing original model. Its original features are linked with the profound heterogeneity of operators and their specialization according to different spatial levels embodied in each other.We present the strategies of those different operators, and a typology of them, based upon a distinction between financial logic and institutional. The first one governs the activity of private organs intending to make profit from spatial amenities provided by their local insertion. The second one comes from the growing responsibility taken by local public authorities to overcome the dramatic subcapitalization of small and medium firms.Even if the offer of equity to those firms is still missing, a new paradigm of regional development is bound to emerge in France from the interdependencies between public and private funding.
Keywords: Développement régional et local, Capital de risque, Financement de la création, Financement de l'innovation, Collectivités territoriales
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84.More information
Emotional approaches in social sciences are very diverse, but still few integrate emotions to explain the social components of action. This article intends to question the dynamics of collective action by integrating the emotional aspect of social life into a relational perspective. Based on the work of Pierre Livet (2001) and Louis Quéré (2012), emotion is considered to be what binds people to a situation. This relationship is examined in the «emotional work», that is to say the revision of our expectations in an uncertain situation that actors operate to engage in action. The purpose of this article is to show the relationship between the characteristics of emotions felt and the forms of collective mobilizations. This article will be based on the analysis of land-use conflicts around nine extension projects of livestock buildings and wind farms. The dynamics of the conflict will be restored in time across the different emotional situations that the protagonists go through.
Keywords: Travail émotionnel, conflit, éolienne, élevage, confiance, action collective, mobilisation, Emotional Work, Conflict, Wind Farm, Animal Farming, Trust, Collective Action, Mobilization
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85.More information
This article accounts for the slow unveiling of the importance of female work on the farms. It aims at understanding why the work of women on the farms has generally been denied and has remained invisible, and why it may become visible in certain situations. It contends that the invisibilization as well as the visibilization of female work on the farm result largely from the way women gain access to this profession and from how the organization of the work on the farm. The article investigates the work of thirty women farmers of two French regions, Britanny and Aquitaine. It first examines their professional careers. Then it analyzes how these female farmers organize their work. Finally it highlights the consequences of their ways of working on the ways they define their professional identity.
Keywords: travail, métier, identité, genre, agriculture, work, labour, professional identity, gender, agriculture
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87.More information
Ports play an essential role in the production and distribution processes of companies, as well as in the networks set up by logistics and transportation service providers. However, they are also likely to have to contribute to the development of the territories where they are established. This paper aims at learning more about how this double challenge impacts the investments made by local and regional ports. To this end, 17 individual websites and 3 French port collective websites have been surveyed. Results show that the sampled ports and groups of ports have for the most part properly adjusted both to the constraints posed by the public authorities, and to the needs and expectations of their current and potential customers.
Keywords: Cruise ports, Ports de croisière, cruise port strategy, stratégie des ports de croisière, cruise line strategy, stratégie des armements de croisière, cruise tourism, tourisme de croisière, cruise ships, navires de croisière
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