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During the glass selection process by optical sorting equipment, a rejection material called CSP (ceramic, stone, and porcelain) is generated, which is lower than 2 wt % of the glass cullet collected in Catalonia (Spain). Although this process should only separate non-glass impurities from the glass cullet, around 84 wt % of glass is found in the CSP. The CSP characterization reveals that CSP is mainly compound by SiO2, Al2O3, alkali metals, and CaO, which are key components for the alkali-activated cement (AAC) development. Consequently, this study is focused on the potential of CSP as a precursor to synthesize AAC. The concentration of the alkali activator (NaOH: 1 M, 4 M, and 8 M) and the liquid-to-solid (L/S) ratio were tested in the formulation of the AAC. The AAC specimens at 28 days cured were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FIR), scanning electron microscopy (SEM), apparent density (ρapp), and compressive strength (σs). The results obtained showed that the L/S of 0.5 and 4.0 M for NaOH concentration are the best conditions, due to the mechanical properties (ρapp = 1.75 g·cm−3, σs = 52.8 MPa), cohesion (SEM), and formed phases (XRD and FT-IR). Therefore, CSP can be a precursor for developing new, sustainable binders.

Cement industry production and its materials demand are growing every year, leading to a CO2 and energy footprint increase. The drinking water production is increasing in water treatment plants due to the population growth, raising in turn the waste materials produced. Since these wastes are mainly managed in landfills, this preliminary research work is focused on providing a new sustainable option for valorisation processes, based on the environmental demand of the cement industry. Alkali-activated cements (AACs) can become a proper option to give the water treatment sludge a new life cycle, as they can compete with ordinary Portland cement (OPC) both in properties and sustainability. The main purpose of this study was to evaluate and formulate different AACs based on the use of both raw clay and the water treatment sludge (WTS), as precursors. The raw clay was used without previous thermal dehydroxylation treatment, and the WTS, an aluminosilicate-rich waste, was used partially replacing the raw clay in the AACs formulations. Both precursors and the formulated AACs were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Fourier-transformed infrared spectroscopy (FT-IR). In addition, the compressive strength, the chemical stability (hydrolytic degradation), and the environmental impact for each AACs formulation were also determined. The results showed that AACs specimens formulated with 20 wt% of WTS (replacing the raw clay) provided the best results, considering both compressive strength and resistance to hydrolytic degradation. Then, it is possible to formulate AACs using raw clay, without prior thermal dehydroxylation treatment, and WTS as precursors. © 2021 Elsevier B.V.

Alkali-activated binders (AABs) stand out as a promising alternative to replace ordinary Portland cement (OPC) due to the possibility of using by-products and wastes in their manufacturing. This paper assessed the potential of weathered bottom ash (WBA) from waste-to-energy plants and PAVAL® (PV), a secondary aluminium recycling process by-product, as precursors of AABs. WBA and PV were mixed at weight ratios of 98/2, 95/5, and 90/10. A mixture of waterglass (WG) and NaOH at different concentrations (4 and 6 M) was used as the alkaline activator solution. The effects of increasing NaOH concentration and PV content were evaluated. Alkali-activated WBA/PV (AA-WBA/PV) binders were obtained. Selective chemical extractions and physicochemical characterization revealed the formation of C-S-H, C-A-S-H, and (N,C)-A-S-H gels. Increasing the NaOH concentration and PV content increased porosity and reduced compressive strength (25.63 to 12.07 MPa). The leaching potential of As and Sb from AA-WBA/PV exceeded the threshold for acceptance in landfills for non-hazardous waste.

Water treatment sludge is an industrial by-product which has recently been classified as a waste by the European Commission. The main goal of this work is to valorise this waste to produce lightweight aggregates. Formulations with sludge substituting expanded clay up to 50 wt% were produced. The physical properties of the lightweight aggregates such as bloating index, density and porosity were studied. The introduction of the sludge without expanding properties, reduced the expandability of the clay and the porosity of the aggregates. The density increased from 0.32 g/cm3 in aggregates without sludge to 1.46 g/cm3 in aggregates with 50 wt% of sludge. It is shown that lightweight aggregates can be produced using mixtures of expanded clay and water treatment sludge, with low substitution percentages (up to 15 wt% of sludge). Aggregates up to 15 wt% of sludge were further studied. The compressive strength increased with sludge wt.%, and the concentrations of heavy metals and metalloids, assessed through leaching tests, were well below the stablished limits. Two preliminary tests of lightweight aggregate concrete were produced: LWAC 1 was formulated with commercial lightweight aggregates and LWAC 2 with aggregates containing 7 wt% of the sludge and commercial lightweight aggregates. The physical, mechanical and thermal properties of LWAC 1 and LWAC 2 were found to be very similar. Our work demonstrates the feasibility in using water treatment sludge as a by-product to produce lightweight aggregates suitable for thermal insulation and lightweight applications.

As the demand for critical and valuable metals increases due to industrial developments, especially in electronics and high-technology industries, the search for novel and sustainable sources grows in significance. Incinerated municipal solid waste (MSW) is a potential source of valuable metals, since a lot of waste from electrical and electronic equipment (WEEE) is not recycled properly and are is managed together with the refuse fraction of MSW, which is often landfilled or incinerated. Bottom Ash (BA) is the main by-product of incinerated MSW, which has been characterized to assess the potential recovery of valuable metals. The determination of the total amount of valuable metals (Ag, Al, Au, Be, Co, Cu, Ga, Ge, In, Ir, Li, Ni, Pd, Pt, Sb, Ta, and W) in seasonal samples of weather bottom ash (WBA) was performed by a total acid digestion followed by a chemical analysis. Besides, a sequential extraction procedure (SEP) is conducted to define their partition. The characterisation has shown that the content of valuable metals in the incineration WBA, which was highest in the 0–2 mm fraction was much lower than in concentrated ores commonly used as primary sources. Moreover, the SEP showed little potential for the valorisation of most of the metals, as they are embedded in or bound to a silicic matrix or sintered metal oxides, and so their extraction requires strong-acid digestion or a highly oxidizing environment. This work contributes to the use of residual sources as secondary resources and to the correct management of the end-of-life electrical and electronic equipment. © 2019 Elsevier Ltd, This work was partially funded by the Spanish Government (BIA2017-83912-C2-1-R). The authors would like to thank the companies SIRUSA and VECSA for their financial support and for providing access to sampling sites. The authors would like to thank the regional Catalan authorities for the accreditation of the quality of the research group: DIOPMA (2017 SGR 118). Mr. Maldonado-Alameda thanks the Catalan authorities for his postgraduate grant (FI-DGR 2017).

Low-grade magnesium oxide (LG-MgO) was proposed as ordinary Portland cement (OPC) or lime substitute (CaO) for metal(loid)s remediation in contaminated soils. Some metal(loid)s precipitate at pH &asymp, 9 in insoluble hydroxide form thus avoiding their leaching. LG-MgO avoids the re-dissolution of certain metal(loid)s at 9.0 &lt, pH &lt, 11.0 (pH-dependents), whose solubility depends on the pH. A highly contaminated soil with heavy metal(loid)s was stabilized using different LG-MgO by-products sources as stabilizing agents. Two of the three studied LG-MgOs were selected for the stabilization, by mixing 5, 10, and 15 wt.%. The effect of using LG-MgO not only depends on the size of the particles, but also on those impurities that are present in the LG-MgO samples. Particle size distribution, X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis, citric acid test, specific surface, bulk density, acid neutralization capacity, batch leaching tests (BLTs), and percolation column tests (PCTs) were techniques used to deeply characterize the different LG-MgO and the contaminated and remediated soils. The remediation&rsquo, s results efficacy indicated that when the medium pH was between 9.0 and 11.0, the concentration of pH-dependent metal(loid)s decreases significantly. Although around 15 wt.% of a stabilizing agent was appropriate for the soil remediation to ensure an alkali reservoir that maintains optimal stabilization conditions for a long period, 5 wt.% of LG-MgO was enough to remedy the contaminated soil. When evaluating a polluted and decontaminated soil, both BLTs and PCTs should be complementary procedures.

Bottom Ash (BA) is the main by-product of municipal solid waste incineration (MSWI). It is stabilised outdoors to obtain weathered bottom ash (WBA) whose main application is in the construction sector as a secondary aggregate for road sub-base. Here, the aim of this work is to advance the study of the potential use of WBA as a precursor in the synthesis of new alkali-activated cements (AACs). An exhaustive physicochemical characterisation (X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy, inductively coupled plasma - optical emission spectroscopy, and Inductively coupled plasma - mass spectroscopy) of WBA was provided depending on its particle size (

Although waste-to-energy plants allow reducing the mass and volume of municipal solid waste (MSW) incinerated, an average around 30 % of the total content remains as bottom ash (BA) and air pollution control (APC) ashes at the end of combustion process. While weathered bottom ash (WBA) is considered a non-hazardous residue that can be revalorized as a secondary aggregate, APC fly ashes generated during the flue gas treatment are classified as hazardous waste and are handled in landfill disposal after stabilization, usually with Portland cement (OPC). However, taking into account the amount of APC residues produced and the disposing cost in landfill, their revalorization is an important issue that could be effectively addressed. As MSW can be incinerated producing bottom ashes (BA) or air pollutant control (APC) residues, the development of a mortar formulated with APC fly ash as secondary building material is a significant risk to the environment for their content of heavy metals. In this way, Design of Experiment (DoE) was used for the improvement of granular material (GM) formulation composed by APC and OPC for further uses as road sub-base aggregate. DoE analysis was successful in the modelling and optimization the formulation as function of the mechanical properties and APC amount. Consequently, an optimal mortar formulation (OMF) of around 50 wt.% APC and 50 wt.% OPC was considered. The OMF leachates and abrasion resistance have been analyzed. These results have demonstrated the viability of OMF as non-hazardous material feasible to be used as secondary aggregate. Moreover, it would be possible to consider the environmental assessment of a GM composed by ≈20 wt.% of OMF and ≈80 wt.% of WBA in order to improve mechanical properties and heavy metals stabilization.

The aim of this article is to present the research carried out over a 10 year period to develop an environmentally safe method for recycling air pollution control (APC) residues. The initial studies aimed to formulate a mixture of weathered bottom ash (WBA), APC residues and Portland cement (PC) to be used as a sub-base in road constructions. Mechanical performance was subsequently enhanced by preparing a mortar prior to mixing it with WBA in order to obtain a granular material. After testing different formulations, the optimum mortar consisted of 50 % APC residues and 50 % PC. The evaluation was carried out based on the concentration release of the heavy metals and metalloids included in the Catalan legislation for revalorization of residues. After the applicability of the granular material was successfully demonstrated at laboratory scale from an environmental and mechanical point of view, a pilot scale plant was designed in order to assess its performance in a real scenario during 4 month. Thus, three roads were built: two containing 100 % granular material and a third containing 100 % WBA. The results showed that the immobilisation of all toxic species from APC residues is accomplished by the pozzolanic effect of the cement. The WBA, APC, and PC proportions show to be the most appropriate for compliance with regard to environmental and mechanics requirements.

Differences during the last 15 years in materials' composition in Municipal Solid Waste Incineration (MSWI) regarding bottom ash (BA) were assessed as a function of particle size (>16, 8 - 16, 4 - 8, 2 - 4, 1 - 2 and 0 - 1 mm). After sieving, fractions greater than 2 mm were carefully washed in order to separate fine particles adhering to bigger particles. The characterization took into account five types of materials: glass (primary and secondary), ceramics (natural and synthetic), non-ferrous metals, ferrous metals and unburned organic matter. The evaluation was performed through a visual (> 2 mm) and chemical (0 - 2 mm) classification. Results showed that total weight of glass in the particles over 16 mm has decreased with respect to 1999. Moreover, the content of glass (primary and secondary) in BA was estimated to be 60.8 wt%, with 26.4 wt% corresponding to primary glass in > 2 mm size fractions. Unlike 1999, in which glass was the predominant material, ceramics are currently the major phase in bottom ash (BA) coarse fractions. As for the metals, respect to 1999, results showed a slight increase in all size fractions. The greatest content (> 22 wt%) of ferromagnetic was observed for the 2 - 4 mm size fraction while the non-ferrous type was almost non-existent in particles over 16 mm, remaining below 10 wt% for the rest fractions. In the finest fractions (< 2 mm), about 60 to 95 % of non-ferrous metals corresponded to metallic aluminium. The results from the chemical characterization also indicated that the finest fractions contributed significantly to the total heavy metals content, especially for Pb, Zn, Cu, Mn and Ti.

[spa] El siguiente trabajo toma como tema principal la inclusión de los recolectores informales en sistemas de gestión formal de residuos sólidos municipales (RSM). Los RSM son un elemento presente desde los primeros asentamientos del hombre, pero los problemas de exclusión se han ido desarrollando conforme ha ido pasando el tiempo y el progreso. Pasado, presente y futuro, tres espacios temporales distantes y a la vez unidos, espacios donde los actos humanos del pasado muestran sus efectos en el día de hoy y donde la única forma de mejorar el futuro es trabajar en el presente aprendiendo del pasado. Dada la complejidad del cuestionamiento, hemos basado nuestro estudio en casos exitosos de modelos de gestión de RSM inclusivos, comenzando un recorrido bibliográfico que nos permitiera abordar de la mejor forma nuestro planteamiento. Con ello, posteriormente hemos comenzado por estudiar el caso de Pune (India). La investigación de primera mano se centra en 3 casos europeos: Traperos de Emaús en Navarra, Engrunes en Cataluña y Amelior en Francia. Los casos son diferentes en sí, pero los une su origen: todos ellos resultaron de la respuesta por parte de vecinos ante un problema o caso de injusticia social. Además, poseen en común que sus usuarios son personas que se dedican a la recolección informal de RSM. Emaús nace en Francia y luego se ha replicado en todo el mundo. Lo cierto es que las comunidades de Emaús nacen generalmente como una respuesta ante la situación de injusticia que sufren personas excluidas. Su forma de vida es la comunidad, escuela personal y colectiva. Su ámbito de trabajo es el espacio liberado en resistencia. En sus orígenes los traperos han utilizado la recolección informal como un evento económico. Sólo el paso del tiempo y las relaciones con otros organismos los han llevado a madurar e internalizar la labor medioambiental que desarrollan. Al día de hoy continúan trabajando con los RSM, ya no de forma precaria ni informal, y con su experiencia han sabido ganar el espacio y ser incluidos en el sistema formal de gestión de RSM. Engrunes es un poco más joven. También nació como respuesta ante la precariedad en que vivían personas del barrio que se dedicaban a la recolección informal como un medio de subsistencia económica. Una respuesta que vino de los feligreses de la parroquia Sant Mateu de Esplugues de Llobregat para ir en su ayuda. Un comienzo similar al de Emaús, con una comunidad y una organización lineal que, con el tiempo va a evolucionar y pasar a constituirse como empresa de reinserción. Con ello, dejaron atrás la vida comunitaria y adquirieron una figura empresarial, pasando a formar parte de la red de Empresas de reinserción del gobierno catalán. Desde este momento sus usuarios llegan procedentes de los programas y servicios de inserción de la administración pública y por un período de tiempo limitado. La recogida de RSM pasó desde la informal con el carrito por las calles y comercio del barrio, a camiones y furgonetas para la recogida dentro del sistema formal, y su herramienta de trabajo contra la exclusión es ahora el contrato de trabajo. Amelior es una asociación nacida hace pocos años en Montreuil y con un ámbito de trabajo que no se centra en la recolección de RSM, sino que lo hace en los recolectores de objetos o biffins. Nace como respuesta ante una situación de injusticia. Esta vez es la escalada de la represión con que el gobierno local trata a los biffins, casi llegando al límite de una verdadera expulsión de los lugares tradicionales donde desarrollaban sus mercadillos de segunda mano. El trabajo de Amelior es encontrar espacios donde puedan establecer sus mercados sin temor de su propia integridad o de sus productos. En su corta vida, han logrado conseguir la plaza del metro Croix de Chavaux como espacio donde, una vez al mes los biffins puedan montar su mercado, siempre organizados y coordinados por Amelior. La situación de los recolectores informales es real, no solo en los países pobres, sino que está presente en todo el mundo. Ahora bien, es un problema que en países como España no está del todo asimilado ni tampoco las autoridades dedican planes para su inclusión, de aquí que determinados ciudadanos se organicen y busquen por ellos mismos sus propios canales para ayudar, organizar, capacitar y lograr modelos inclusivos con los cuales poder luchar contra le exclusión. En Francia, el gobierno ha ido cediendo a la presión de otorgar espacios, quizás como forma de controlar a los biffins y evitar el mercado en zonas de interés gubernamental, como las zonas turísticas de Paris. Nuestro estudio logró demostrar que modelos inclusivos de gestión de RSM orientados al Zero Waste son aplicables en diferentes escenarios, por diferentes que sean. En cuanto a la prevención de residuos, los recolectores informales contribuyen a la economía solidaria, especialmente al convertir desechos en productos de segunda mano accesibles para personas de bajo poder adquisitivo o que rechazan la economía de consumo. Paralelo a ello, los modelos inclusivos generan trabajo regulado y, con ello contribuyen a mejorar la calidad de vida de los recolectores dignificando sus vidas. La sola recuperación de desechos o material para el reciclaje contribuya a su vez a la disminución de la cantidad de RSM que debe ser llevado a depósito controlado. Finalmente decir que se ha demostrado que un modelo de gestión híbrido, en el sentido de ocupar a personas en exclusión como parte del sistema formal contribuye a mejorar el sistema de recogida, dada la experiencia en recogida selectiva de éstos. Se ha visto que la hoja de ruta no es fácil ni corta, pero los modelos inclusivos llevan a mejorar tanto aspectos sociales como medio ambientales. No se pueden generar cambios al corto plazo, pero tampoco se puede esperar ver cambios sin comenzar un camino de trabajo., [eng] This work carry out a research taking as central issue the inclusion of the informal waste collectors (waste pickers) into formal waste management systems. The MSW have been present since the first settlements of the humanity, but social and exclusions problems have been developing in the hand of time and progress. Past, present and future, three distant dimensions in time and united too. Temporary spaces where human acts in the past present effects in the present and where the only way to improve the future is work from the present, studing the past. Given the complexity of, a priori, the question, we have based our research in successful cases of inclusive MSW management systems (MSM). The first step was a bibliographic research that allow us to take a correct approach. Then, we begun to study the case of Pune (India). The first-hand research focuses on 3 European cases: Traperos de Emmaus in Navarra, Engrunes in Catalonia and Amelior in Montreuil, France. The cases are different in themselves, but they are linked by their origin: all of them were born like a response by neighbors to make front a problem or a social injustice case. In addition, they have in common that their users are people engaged into the informal collection of MSW. Emaus was born in France and then has been replicated around all the world. The Emaus communities was born like a response to the situation of injustice suffered by excluded people. Their way of life is community, personal and collective school. Some Emaus ragpickers say: “our ambit of work is a space released in resistance". In its origins, the ragpickers have used informal waste pickering just as an economic event. Only the pass of time and relations with other organisms made possible a maturation and internalizing of they work like a utility work to the society and environment. Actually, they continue to work with the MSW, but no longer in a precarious or informal way, and with their experience they have been able to gain space and be included in the formal MSW management system. Engrunes is a little younger. It was also born as a response to the precariousness of homeless living in the neighborhood and were engaged in informal recollection as a means of economic subsistence. A reaction that came from a little group of people of the Sant Mateu church from Esplugues de Llobregat to help them. A similar begin that Emaus, with a community and a linear organization that, over time, will evolve and become into a reinsertion enterprise. With this step, they left behind the community life and acquired an enterprise figure, becoming part of the Insertion enterprises network the Catalan government. From this moment, its users arrive by just one way: programs and insertion services of the public administration, and that’s is not all, it’s just for a limited time. The waste collection went from the informal with the typical cart, to trucks and vans for collection inside the formal system. Actually, the tool to work against the exclusion is the contract of employment. Amelior is an association born a few years ago in Montreuil. Their work that not focus on the collection of MSW, their works is focalized with the waste pickers (biffins) rights. The association, like Emaús and Engrunes, was born as a reaction front an injustice situation. In this case, the reactions were produced by the increment in repression and persecution by the government of Paris against the biffins. Situations like the prohibition to use traditional places for its market and, in the last times with the expulsion to the periphery areas of Paris. Amelior's task can be resumed in one objective: find spaces where they can establish their markets without fear for their own integrity or of their products. In their short life they have achieved, by a public bidding, the use of the Croix de Chavaux square as a market space one time by month. The situation of the excluded people, like waste pickers, is real. And is not present just in poor countries, they are present around the world. However, it is a problem that in countries like Spain is not fully assimilated for the authorities, or the govern don't dedicate plans for their inclusion. This situation make that some citizens organize themselves and search how they can help to organize, capacity and arrive to legal and accepted models to combat exclusion. In France, the government has been opening to listening the demands, maybe to the pressure, to grant spaces, maybe just a way to control the biffins and avoid the market in areas of governmental interest, read touristic interests, of Paris. Our study was able to demonstrate that Zero Waste models of MSW management are applicable in different scenarios, even if they have some differences into waste prevention theme, informal collectors contribute to the solidarity economy, especially by converting some products discarded and dumped by somewhere, into second-hand products accessible for another people with low purchasing power, or people who reject the consumer economy. In parallel, the inclusive models generate regulated work and, with this, contribute to improve the quality of life of the waste pickers, dignifying their lives. At the same time, the simple action to recovery for the waste or material for recycling, contributes to the decrease of the amount of MSW that must be taken to transported and dumped in a landfill. Finally, we have been demonstrated that, a hybrid management model, in the sense of occupying exclusion people as part, or inside the formal management system contributes to improve the waste collection system, given their experience in the selective collection based in the recuperation of quality products from the waste. We have been seen that the road map is not easy nor short, but the inclusive models lead to social and environmental improvement. It's impossible generate changes in the short term, but also cannot see changes if we don't start a working plan.

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2014-2015, Tutor: Joan Mata Álvarez, Dependence on conventional plastics and their boundless usage have resulted in waste accumulation and greenhouse gas emissions. Part of a solution lies in using biodegradable plastics such as polyhydroxyalkanoates (PHA), which can be produced by bacterial fermentation. The interest in these biopolymers lies in its similar properties to conventional plastics. However, its price is still too high to compete in the current market. One way to produce PHA reducing the cost of production is to use wastes and wastewater as a raw material. They have not only a great capacity to produce PHA with a high potential for accumulation but also to reduce the costs of the waste and wastewater treatment. The process to produce PHAs from waste consists of three steps: an anaerobic fermentation process, the enrichment of the culture and the accumulation of PHA. The fermentation process, to produce volatile fatty acids, is required when carbohydrate wastes are used as substrate. The main challenge in PHA mixed culture processes is the enrichment of PHA-accumulating organisms, which can be carried out with transient conditions of carbon supply, i.e. feast-famine regime. This process configuration creates periods of excess and lack of external carbon substrate. Following a certain period of time in the absence of external carbon substrate, a decrease of the amount of intracellular components required for cell growth (RNA and enzymes) occurs. Therefore, when carbon substrate becomes available again, the amount of growth enzymes may not be enough to ensure that a maximum growth rate is reached. On the contrary, fewer enzymes are required for PHA storage and, therefore, PHA storage can occur at a much faster rate than cell growth, thus providing the cells with a means of rapidly consuming the available external substrate. This work presents an economic analysis of PHA production by bacterial fermentation from municipal wastes. Based on an annual production of 2503 tones of PHA, and taking into account the performance of production processes of PHA is 0.33 g PHA/ g VFA-COD approximately, the economic potential which is obtained is not still sufficiently positive. However, if this investigation line continues, it has been seen that the process can be viable and an effective industrial wastewater treatment technology

Treballs Finals de Grau d'Enginyeria Química, Facultat de Química, Universitat de Barcelona, Curs: 2013-2014, Tutors: Joan Dosta Parras i César Alberto Valderrama Angel, The recovery of phosphorus from wastewater appears to be the best option to ensure the recyclability of this product and save the fertiliser industry from losing its key element. Chemical precipitation is an effective method to obtain calcium phosphate in the form of hydroxyapatite (HAP), which can be applied to the soil as a fertiliser. In a Waste Water Treatment Plant (WWTP), the liquid effluent from the secondary clarifier is rich in phosphorus. This effluent can be introduced in an ion exchange unit that, when being regenerated, produces a solution with a concentration up to 1,000 mg PO43-/L. This stream can undergo chemical precipitation thanks to the addition of calcium ions with alkaline media. Concentrate or reject stream obtained from nanofiltration (NF) or reverse osmosis (RO) processes can be used as a source of calcium, valorising both wastewater and brines. A laboratory scale study is conducted using a semi continuous stirred batch reactor to precipitate phosphate of a solution that simulates the regenerated stream in the ion-exchange unit of a WWTP, using nanofiltration and reverse osmosis brines with and without Mg2+ at different pH. Results indicate that the presence of Mg2+ enhances phosphate removal, but does not stimulate HAP formation. The conditions that achieve higher phosphate removal are the NF and RO brines with Mg2+ at pH=10.5, representing almost a 100 % of removal. In all four types of brines, higher removal is obtained at pH=10.5. The type of brine does not have as much effect as other factors such as the presence of Mg2+ or pH. In less time, NF brine removes the same amount of phosphate from the solution than RO brine when there is Mg2+.

Treballs Finals de Grau Antropologia Social i Cultural, Facultat de Geografia i Història, Universitat de Barcelona, Curs: 2012-2013, Tutor: Carlos Siches Cuadra, Con la cantidad de alimentos que desecha el sistema de mercado como telón de fondo, así como con el actual contexto de crisis económica −en el que impera el paro, el trabajo precario y mal pagado, etc.−, se abordan las prácticas y concepciones entorno a la recuperación de residuos alimentarios como estrategia de supervivencia, tomada por algunas personas que se ven afectadas por las dificultades propias del momento en Barcelona. Para este fin se tienen en cuenta las causas por las que se propician los residuos alimentarios; las circunstancias que implican recurrir a ellos; su conceptualización social; veteranía, lugares, horarios, constancia, precauciones y dificultades en recuperarlos; los sentimientos que brotan ante esta manera de obtenerlos y vivir gracias a ellos; y las consideraciones frente a las medidas legales que chocan contra esta forma de procurarse el sustento.

La anodización es un proceso electrolítico que convierte la superficie metálica en un recubrimiento de óxido insoluble. El aluminio es el material anodizado con más frecuencia. El llamado “abrillantado” del aluminio se realiza comúnmente con baños de ácido fosfórico concentrado. Después de la anodización, las piezas deben enjuagarse cuidadosamente, y es en ésta operación en la que se produce una dilución de la solución del baño arrastrada en la capa de óxido formada. Es en este aspecto donde se plantea la mejora de la calidad medioambiental del sector mediante un plan de recuperación y reutilización de los ácidos diluidos en las aguas de lavado, especialmente del ácido fosfórico. Las membranas son una herramienta atractiva que ofrece un amplio rango de aplicaciones, especialmente en el campo de la alimentación, bebidas, bioquímica, etc. Hay muchos ejemplos que pueden encontrarse en el tratamiento de efluentes, la desalinización de aguas o la concentración de soluciones. La separación de diferentes componentes se consigue por la acción de una membrana separadora y por la influencia de una fuerza impulsora a ambos lados de la membrana (presión, concentración, campo eléctrico). Son objetivos de este trabajo: Realizar un aporte a la investigación sobre la recuperación de materia prima en efluentes industriales mediante técnicas de membrana El eficaz aprovechamiento de la materia prima mediante el reciclado de los ácidos a los baños de anodizado La reducción del volumen de aguas residuales finales, con la correspondiente reducción en la contaminación ambiental del medio receptor La elaboración de una propuesta técnico-económica innovadora en el sector del recubrimiento metálico Los principales resultados obtenidos son: Se ha encontrado que las membranas de nanofiltración DK de Osmonics y la MPF-34 de Koch permiten una adecuada separación entre el Al3+ y los ácidos fosfórico y sulfúrico de las aguas de lavado. Los rechazos promedio (del ensayo de concentración) de Al3+ y H3PO4 para la membrana MPF-34 son de 99,7% y de 66,9% respectivamente y para la membrana DK de 99,5% y de 32,3% respectivamente. - Se han desarrollado expresiones para poder estimar adecuadamente los rechazos de Al3+, H3PO4 y H2PO4- en función de la composición del alimento con la membrana MPF-34. Se ha visto que estos valores son los intrínsecos de la membrana. Estas expresiones se obtuvieron mediante un estudio fenomenológico debido a que la complejidad del problema no permite hacerlo desde el punto de vista mecanístico. Se ha encontrado que la estabilidad de la membrana DK en el medio ácido del alimento es suficiente para asegurar un funcionamiento adecuado a nivel industrial. Un tratamiento utilizando la membrana DK permite una recuperación del 73% del ácido fosfórico. En el ácido fosfórico recuperado la relación Al/H3PO4 es de 0,11% en peso mientras que en la disolución alimento inicial era de 6%. Se ha visto que las membranas tanto poliméricas como cerámicas con un PMC de 1000 Da o más no permiten una recuperación adecuada del ácido fosfórico, debido a que el máximo rechazo de Al alcanzado ha sido del 58%. Para las condiciones estudiadas y debido a la naturaleza del las disoluciones tratadas la electrodiálisis no permite una recuperación adecuada del ácido fosfórico Se ha visto que la UFAP no permite separar el Al debido a que no es posible formar complejos Al-Polímero en medios ácidos como el del alimento. La adición de especies que permitan variar el pH de las disoluciones complicaría la recuperación del ácido debido a la presencia de impurezas adicionales., Most of the hazardous waste in a metal finishing operation comes from the wastewater generated by rinsing operations. The acidic solution that is dragged out from the bath into the following rinsing tanks is the primary source of contamination of rinse water. The use of acidic solutions is very common in metal processing. Sulphuric acid, hydrochloric acid, phosphoric acid, chromic acid and nitric acid are used in chemical bath for anodising, galvanising, brightening, plating and pickling process. The known strategies to reduce the pollution in the wastewater effluent are based on the recovery of contaminant compounds to be recycled to the process reducing the expense in fresh compounds. By definition, recycling includes all measures in order to reduce volume of effluent by recovery raw materials from wastewaters. Membrane separation has become a competitive technology to traditional water treatment processes because of highly effective in removing most inorganic and organic contents to produce a very pure effluent.