Jacques Bourgois

Dynamic Waste Management (DWM): A new step towards industrial ecology

The load caused by growing volumes of collected residues produces a pressure both on the environment and on the population. Presently, wastes are no longer considered just simple residues, but also resources which can be reused or recovered. Various tools are now available to help compare the various options in waste management. These tools lead to a linear management of the systems. In addition, they generate a division of flow streams and do not allow an optimal use of the available materials. An industrial ecology perspective requires one to move towards a systemic approach. Based on the law of conservation of energy, the Dynamic Waste Management approach (DWM) studies the behaviour of systems to insure a constant supply of favourable waste management options (WMO) and to reduce the global load within these systems. The flow distribution in a global system rests on the principle that the available volumes and the transportation influence the validity of the hierarchical organisation of WMO. Adhering to the philosophy of industrial ecology, the DWM offers a dynamic and evolutionary alternative to reduce the impacts generated by inadequate waste management. The present article exposes the characteristics of the proposed approach, and presents an example of its application in order to demonstrate the advantages of the DWM.

Valorisation of Polymetallic Hydroxide Sludge as Pollutant Trappers

Metal finishing industries produce an important tonnage of metal hydroxide sludge (MHS) during the treatment of their liquid effluents charged with heavy metals. Generally, a small part of these sludge is valorized because of their important metal fickleness. Consequently, the majority of these metal hydroxide sludge is sent to landfill centers. We propose to valorize this sludge by using them as pollutant sorbent in order to retain the polluting species contained in the industrial aqueous effluents. The chosen pollutant for this preliminary study is Chromium (+VI). Starting from an experimental well defined protocol, various parameters have been studied (chemical nature of the sludge, solid/liquid ratio, concentration of the pollutant, particle size) in order to determine the experimental parameters which influence the sorption yield of these sludge and thus to validate the feasibility of an industrial application of this new way of valorisation. First results point out that the sorption yield is more than 95% independently from the experimental conditions. Moreover, experiments highlight that the sludge mass (and so sorbent sites) is THE only real parameter which influences the yield. In this article, a review of the patents on different aspects of the valorisation of polymetallic hydroxide sludge as pollutant trappers is presented.

Drag-Out in Metal Finishing Industries

Currently, environmental regulations induce industrialists to implement source reduction techniques in order to comply with the prevention principle toward sustainable development. The project PIPSI (PIlotage Propre des Systèmes Industriels/industrial system clean piloting) financing by Rhone-Alps Region is carried out with the aim to contribute to this objective. The study presented in this article concerns the pollution transfer in a metal finishing treatment line in order to minimise the environmental impact obtained notably with the pollution balance. Drag-out and draining phenomena have been particularly studied. Results obtained showed that a 10 seconds of draining reduced drag-out from 65 to 85% in terms of pieces design. Moreover, during the experiments, 5 drag-out levels were identified by medium values from 26 to 1700 ml m−2. So that, either a piece can be associated to a level or knowing the piece drag-out level, it is possible to evaluate its medium drag-out value. Then the pollution balance will be obtained more easily.