Use of LCA to evaluate the environmental benefits of substituting chromic acid anodizing (CAA)

Chromic acid anodizing processes are currently being replaced in many industrial sectors because of the recognized adverse effect on the environment and health of used hexavalent chromium compounds. The environmental impacts of the existing processes must, however, be quantified in order to constitute a baseline against which the environmental performance of potential alternative options could be compared. The whole life cycle of the process should also be taken into account to ensure that the possible chosen solution for eliminating or lowering chromium (VI) emissions would not drastically damage the overall process performance in other environmental areas. In our study, we used a simplified life cycle assessment methodology that only took into account the key environmental issues of the considered industrial sector. Both the scope and the data needs were reduced by focusing only on significant flows and by using a generic database for steps other than the anodizing one. A precise literature review was carried out to evaluate bath atmospheric emissions. The results of the performed assessment confirmed that the only way to efficiently deal with hexavalent chromium compounds is to substitute the electrolyte used in the bath as the most Cr(VI) emissions are caused by other stages than the main one. Other specific issues, such as water and energy consumptions have, nevertheless, to be studied throughout the whole life cycle of the chemical substitute to monitor performance against CAA.AIRBU

ReSICLED: a new recovery-conscious design method for complex products based on a multicriteria assessment of the recoverability

Significant improvements in end-of-life complex product recovery can be accomplished when recovery aspects are better integrated at the design stage of products. This paper introduces a new method that should allow design teams to produce better recovery-conscious designs, i.e. to integrate the complexity and the variability of recovery routes and to make recoverability more tangible to designers. The main methodological aspects of the new method are presented based on an analysis of the strengths and weaknesses of existing methods. In particular, the original multiprocess modelling of recovery scenarios and the original quantitative, multicriteria and multiscenario assessment of the recoverability of a product are detailed. On the basis of the assessment results, a design team is able to suggest design improvements. The implementation of the new method is simulated in real industrial practice. It is shown how the use of the method can bring significant gains in the product’s recoverability. Assets and drawbacks of the method are discussed.Région Rhône-Alpe

Sorting mixed polymers from end of life products by a selective grinding process

European policy on waste and market demand for material are driving the development of sorting techniques adapted to automobiles and electric products at the end of their lifetimes. In this article, we present work on polymer sorting using selective grinding. Selective grinding is an operation that consists in sorting polymers after shredding. Specific particle size distributions characterize each polymer in the output stream and these differences are used to recover certain polymers by sifting. This process is based on the brittle or ductile properties of polymers. The first results presented in this work concern the sorting of a mixture of polymers and polyolefins, which are chemically incompatible. The working method adopted includes three parts. In the first part, a stream of mixed polymers from the shredder residue (SR) of a treatment chain was characterized. The mixed stream was composed of different grades of Polypropylene and different grades of Polyethylene. Afterwards, based on the characterization data, selective grinding tests were carried out on a model mixture with virgin materials. Once the selective grinding conditions were validated, other tests were carried out with shredder residues. The conclusion of this study is that selective grinding can be an efficient technology to sort incompatible polymers, which are not sorted by other processes, such as density separation or automated near infrared sorting.ANR TRICOTO

State of the art of plastic sorting and recycling : Feedback to vehicle design

Today car manufacturers are beginning to integrate recycling constraints in the first stages of the design of a new car due to their concern regarding the effects of car design on the recovery of material after End-of-Life Vehicle treatment. Improved understanding of the recycling process can help designers to avoid contaminants in the recycled product and improve the efficiency of current and new sorting methods. The main goal of this paper is to describe the state of the art of the technical efficiency of recovery channels for plastics in Europe in order to define requirements for automotive plastic part design. This paper will first present the results of a survey on industrial and innovative recycling technologies mainly originating from the mining sector, and secondly a simplified methodology for car design integrating plastic recycling constraints. This methodology concerns material association and compatibility, the type of assemblies favourable to better recycling, and better reuse of recycled products in cars.Renault Research Direction FR TCR LAB 1 13, Service 641000-Recycling Engineering, 1 avenue du Golf, 78288 Guyancourt Cedex, Franc

Polymer tracer detection systems with UV fluorescence spectrometry to improve product reyclability

The recycling of materials originating from end-of life products is essential to preserve our raw material resources, which are increasingly expensive and whose extraction is increasingly impactful for the environment.However, certain materials are still not recycled today. In the case of plastics, their recycling includes grinding, which generates complex mixtures. It is not possible to sort these mixtures and reach a high degree of purity with the existing physico-chemical processes. Automated sorting processes using near infrared spectroscopy are limited to dark-colored materials. One option is to add tracers to virgin materials to allow identification and rapid sorting of end-of-life products, using UV fluorescence spectrometry as the identification technique. The optimization of the polymer/tracer/detection system is based on several criteria: the reliability and speed of detection of UV fluorescence tracers added to a polymer matrix with carbon black, the relevance of the environmental impact of the tracers, and the preservation of the mechanical properties of the polymer with the tracers added.International audienceThe recycling of materials originating from end-of life products is essential to preserve our raw material resources, which are increasingly expensive and whose extraction is increasingly impactful for the environment.However, certain materials are still not recycled today. In the case of plastics, their recycling includes grinding, which generates complex mixtures. It is not possible to sort these mixtures and reach a high degree of purity with the existing physico-chemical processes. Automated sorting processes using near infrared spectroscopy are limited to dark-colored materials. One option is to add tracers to virgin materials to allow identification and rapid sorting of end-of-life products, using UV fluorescence spectrometry as the identification technique. The optimization of the polymer/tracer/detection system is based on several criteria: the reliability and speed of detection of UV fluorescence tracers added to a polymer matrix with carbon black, the relevance of the environmental impact of the tracers, and the preservation of the mechanical properties of the polymer with the tracers added

A study on the dispersion, preparation, characterization and photo-degradation of polypropylene traced with rare earth oxides

This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix.This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix

Addition of X-ray fluorescent tracers into polymers, new technology for automatic sorting of plastics : proposal for selecting some relevant tracers

A description of a new technology for automatic sorting of plastics, based on X-ray fluorescence detection of tracers, added in such materials is presented. This study describes the criteria for the selection of tracers, and concluded that the most adapted for XRF are some rare earth oxides. The plastics chosen for tracing and identification are the ones contained in ELV and WEEE from which discrimination is difficult for the existing sorting techniques due to their black colour.A description of a new technology for automatic sorting of plastics, based on X-ray fluorescence detection of tracers, added in such materials is presented. This study describes the criteria for the selection of tracers, and concluded that the most adapted for XRF are some rare earth oxides. The plastics chosen for tracing and identification are the ones contained in ELV and WEEE from which discrimination is difficult for the existing sorting techniques due to their black colour

Characterizing plastics originating from WEEE: A case study in France

Two studies, TRIPLE (For Analyse des gisements DEEE et optimisation des technologies de TRI des PLastiques EEE (analysis of WEEE and optimization of sorting technologies for WEEE plastics). and VALEEE For VALorisation des composants, matières et substances issus du gisement DEEE (Recovery of components, materials and substances from WEEE).), supported by the French State, the Greater Lyon area (Grand-Lyon), the Rhône-Alpes Region and the French eco-organization ‘‘Eco-systèmes’’, and involving laboratories, recycled material users and recycler partners, were conducted concerning the characterization, sorting and recovery of French WEEE (Waste Electrical and Electronic Equipment). To determine the heterogeneity of a 10-ton batch, the WEEE was sorted into families before grinding. Specimens were dismantled and plastic particles were analyzed to estimate their composition. The batch was then crushed and the metals extracted. The residue containing plastics was sampled at the outlet of the plant and analyzed. The detailed characterization of the plastics sample was used to calculate the estimated sampling error and the overall measurement error. The sample size was determined so as to achieve satisfactory accuracy for the most represented polymers likely to be recovered after recycling. A simple characterization methodology for use by recycling plants was proposed in order to determine the plastic composition of this waste. The procedure was validated on a second 10-ton batch of sWEEE collected from another location and treated by a different recycling facility. This article presents the sampling protocol design methodology, then the characterization protocol and its usage limitations.FUI TRIPLE et VALEE

Fresh water distribution problematic in Nouakchott

Because of its geographical location, Mauritania is characterized by an arid climate. The water resources are thus limited. The annual average rainfall calculated by M.Yeslem [1] over a 60-years period (1931-1991) is 112 mm. Nouakchott, the Mauritanian capital, knew an exceptional growth of the population, carrying it to more than 700 000 inhabitants in the year 2005 [2]. These brisk demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures and in particular for drinking water. Balloffet E.[3] and Seureca A.[4] indicate that the needs of the population of Nouakchott for drinking water, supplied from underground lake of Idini, increased exponentially the last years, in spite of the fragility of the system for which overexploitation could be prejudicial with the resources. This situation was accentuated by the lack of planning and of a framework of urban regulation. In these particular circumstances, the inhabitants of the town of Nouakchott suffer from all problems related to Water resource availability and quality. This study, carried out over a representative sample of Nouakchott's population coming from two poor districts and a rich one, shows that the rate of access to distribution network, to the sanitation network and accessibility to water are very low for the two poor districts of El Mina and Sebkha. 22%, 4% and 35% of the population had access to the above networks. These meduim rates, are due to households in the district of Tevragh-Zeina (a rich area). In addition, this work shows that the vulnerability of the distributed water is big because of the non generalization of the supplying network. In fact, the results of our physico-chemical and bacteriological analyses/tests carried out on site, in different points of the distribution channel, show that the physico-chemical characteristics of the water conform to the World Health Organization (WHO)'s norms. However, the terminal fountains were found to be contaminated with total and fecal coliforms.This work, based on laboratory diagnosis and analyses results, can be an important prerequisite for the installation of an environment and public health management system associated with the quality of the distributed water in Nouakchott.Because of its geographical location, Mauritania is characterized by an arid climate. The water resources are thus limited. The annual average rainfall calculated by M.Yeslem [1] over a 60-years period (1931-1991) is 112 mm. Nouakchott, the Mauritanian capital, knew an exceptional growth of the population, carrying it to more than 700 000 inhabitants in the year 2005 [2]. These brisk demographic trends generated a fast expansion of occupied space and a strong pressure on the social equipments and basic infrastructures and in particular for drinking water. Balloffet E.[3] and Seureca A.[4] indicate that the needs of the population of Nouakchott for drinking water, supplied from underground lake of Idini, increased exponentially the last years, in spite of the fragility of the system for which overexploitation could be prejudicial with the resources. This situation was accentuated by the lack of planning and of a framework of urban regulation. In these particular circumstances, the inhabitants of the town of Nouakchott suffer from all problems related to Water resource availability and quality. This study, carried out over a representative sample of Nouakchott's population coming from two poor districts and a rich one, shows that the rate of access to distribution network, to the sanitation network and accessibility to water are very low for the two poor districts of El Mina and Sebkha. 22%, 4% and 35% of the population had access to the above networks. These meduim rates, are due to households in the district of Tevragh-Zeina (a rich area). In addition, this work shows that the vulnerability of the distributed water is big because of the non generalization of the supplying network. In fact, the results of our physico-chemical and bacteriological analyses/tests carried out on site, in different points of the distribution channel, show that the physico-chemical characteristics of the water conform to the World Health Organization (WHO)'s norms. However, the terminal fountains were found to be contaminated with total and fecal coliforms.This work, based on laboratory diagnosis and analyses results, can be an important prerequisite for the installation of an environment and public health management system associated with the quality of the distributed water in Nouakchott

Use of LCA to evaluate the environmental benefits of substituting chromic acid anodizing (CAA)

Chromic acid anodizing processes are currently being replaced in many industrial sectors because of the recognized adverse effect on the environment and health of used hexavalent chromium compounds. The environmental impacts of the existing processes must, however, be quantified in order to constitute a baseline against which the environmental performance of potential alternative options could be compared. The whole life cycle of the process should also be taken into account to ensure that the possible chosen solution for eliminating or lowering chromium (VI) emissions would not drastically damage the overall process performance in other environmental areas. In our study, we used a simplified life cycle assessment methodology that only took into account the key environmental issues of the considered industrial sector. Both the scope and the data needs were reduced by focusing only on significant flows and by using a generic database for steps other than the anodizing one. A precise literature review was carried out to evaluate bath atmospheric emissions. The results of the performed assessment confirmed that the only way to efficiently deal with hexavalent chromium compounds is to substitute the electrolyte used in the bath as the most Cr(VI) emissions are caused by other stages than the main one. Other specific issues, such as water and energy consumptions have, nevertheless, to be studied throughout the whole life cycle of the chemical substitute to monitor performance against CAA.AIRBU