Gara Villalba

Removal of ammonium and phosphates from wastewater resulting from the process of cochineal extraction using MgO-containing by-product

The wastewater produced by the cochineal extract process to obtain the carminic acid colouring pigment (carmin red E120) has high concentrations of phosphates and ammonium. It is known that both ions can be precipitated with magnesium in the form of struvite, MgNH(4)PO(4), or ammonium magnesium phosphate (MAP) compounds. In this study, the use of an alternative MgO-containing by-product is investigated. The optimal pH, reaction time and solid/liquid ratio have been studied. It has been found that the low-grade MgO needed is greater than the stoichiometric value for the full removal of ammonium and phosphate as MAP compounds. Although the low-grade MgO (LG-MgO) reacts slower than pure MgO, it has considerable economic advantages. A batch process has been proposed for the removal of ammonium and phosphates from wastewater obtained in cochineal extracts processing, previously to biological treatment to diminish the COD.

Life cycle assessment of biogas upgrading technologies

This article evaluates the life cycle assessment (LCA) of three biogas upgrading technologies. An in-depth study and evaluation was conducted on high pressure water scrubbing (HPWS), as well as alkaline with regeneration (AwR) and bottom ash upgrading (BABIU), which additionally offer carbon storage. AwR and BABIU are two novel technologies that utilize waste from municipal solid waste incinerators - namely bottom ash (BA) and air pollution control residues (APC) - and are able to store CO(2) from biogas through accelerated carbonation processes. These are compared to high pressure water scrubbing (HPWS) which is a widely used technology in Europe. The AwR uses an alkaline solution to remove the CO(2) and then the solution - rich in carbonate and bicarbonate ions - is regenerated through carbonation of APC. The BABIU process directly exposes the gas to the BA to remove and immediately store the CO(2), again by carbonation. It was determined that the AwR process had an 84% higher impact in all LCA categories largely due to the energy intensive production of the alkaline reactants. The BABIU process had the lowest impact in most categories even when compared to five other CO(2) capture technologies on the market. AwR and BABIU have a particularly low impact in the global warming potential category as a result of the immediate storage of the CO(2). For AwR, it was determined that using NaOH instead of KOH improves its environmental performance by 34%. For the BABIU process the use of renewable energies would improve its impact since accounts for 55% of the impact.

A proposal for quantifying the recyclability of materials

Abstract It is becoming of empirical importance that recyclability be defined in such a way that engineers, economists, and policy makers can agree upon and use collectively. This paper defines recyclability as the ability of a material to reacquire the properties that it had in its virgin state, where virgin state refers to the material in its purest form before being processed or shaped for a specific use. Anything less than that can be measured as a degree of its recyclability, defined as recycling index ( R ). It is here proposed that R of a material can be estimated by its devaluation (how much the material devalues during its first use), which is reflected by its loss of monetary value. This way, R can be calculated by a mathematical expression. Because of their thermodynamic and kinetic properties, as well as advances in their recycling technologies, most metals are recyclable. They are therefore used to establish a relationship that determines how truly recyclable materials should behave.

Global Substance Flow Analysis of Gallium, Germanium, and Indium: Quantification of Extraction, Uses, and Dissipative Losses within Their Anthropogenic Cycles

This study provides a global substance flow analysis for gallium (Ga), germanium (Ge), and indium (In) for 2011, quantifying the amount of metal lost during extraction, beneficiation/smelting/refining, manufacturing of intermediate products, and the amount embodied in end‐use products. Thus far, studies illustrating their cradle to end‐use life cycle on a global scale are either missing or outdated, and thus opportunities to increase their supply remain unknown and/or not quantified. The results illustrate the losses and inefficiencies stages, thereby identifying potential additional supply by process improvement, recovery, and recycling. Results show that there are significant opportunities to meet future demand of Ga and Ge by concentrating recovery efforts in the extraction and beneficiation/smelting/refining stages. Further, 1.4% Ga, 0.7% Ge, and 54% In of the theoretical available amount in the attractor ores are extracted to meet the primary refined demand in 2011. Of the 9,065 tonnes (t) of Ga embodied in the Bayer liquor (from aluminum production), only 263 t are refined. This is owing to low capacities of Ga refining, combined with a refining efficiency of 60%. Ge presents a similar case for the same reasons, in which only 43 t of Ge of the 7,636 t of Ge available from zinc leach residue are refined. Meeting future In demand, on the other hand, will require greater efforts in increasing end‐of‐life recycling. Process efficiencies for Ga (46%), Ge (56%), and In (78%) demonstrate further potential. We quantify the flows into use by distinguishing among dissipative and nondissipative end uses, as well as the recyclable fraction for each metal for 2011.

Upgraded biogas from municipal solid waste for natural gas substitution and CO2 reduction - a case study of Austria, Italy, and Spain.

Biogas is rich in methane and can be further purified through biogas upgrading technologies, presenting a viable alternative to natural gas. Landfills and anaerobic digestors treating municipal solid waste are a large source of such biogas. They therefore offer an attractive opportunity to tap into this potential source of natural gas while at the same time minimizing the global warming impact resulting from methane emissions in waste management schemes (WMS) and fossil fuel consumption reduction. This study looks at the current municipal solid waste flows of Spain, Italy, and Austria over one year (2009), in order to determine how much biogas is generated. Then it examines how much natural gas could be substituted by using four different biogas upgrading technologies. Based on current waste generation rates, exploratory but realistic WMS were created for each country in order to maximize biogas production and potential for natural gas substitution. It was found that the potential substitution of natural gas by biogas resulting from the current WMS seems rather insignificant: 0.2% for Austria, 0.6% for Italy and 0.3% for Spain. However, if the WMS is redesigned to maximize biogas production, these figures can increase to 0.7% for Austria, 1% for Italy and 2% for Spain. Furthermore, the potential CO2 reduction as a consequence of capturing the biogas and replacing fossil fuel can result in up to a 93% reduction of the annual national waste greenhouse gas emissions of Spain and Italy.

Using Web-Based Technology to Bring Hands-On Urban Material Flow Analysis to the Classroom

The main objective of this article is to introduce an open†source, online software tool called OMAT as a teaching tool for performing economy wide†material flow analysis (EW†MFA) at urban or regional level in industrial ecology curricula. To that intent, we present a classroom and project activity that was developed for a masters†level industrial ecology course offered by the Autonomous University of Barcelona. Insights are provided with regards to the outcome of the classroom exercise as well as lessons learned from both an academic and a software development point of view. The OMAT software provides users with a specialized tool to enter and process MFA data in a simple, intuitive way. The usefulness of OMAT as a teaching tool was tested by engaging students in a classroom activity that entailed using OMAT as a tool to perform an EW†MFA applied to the Metropolitan Area of Barcelona for the years 2005†2011. The aim of this exercise was to teach students specific skills required in performing an EW†MFA, not through theory classes, but hands†on through a learn†as†you†go approach. The exercise not only equipped the students with knowledge about MFA, but also introduced them to solving problems as a team, meeting project deadlines, and communicating effectively with colleagues from different disciplines and backgrounds. Even though there is room for further improvements, this exercise showed that OMAT provided a useful addition to traditional methods that allowed students to get a more practical and thorough understanding of the MFA methodology.

Rainwater harvesting systems reduce detergent use

PurposeDue to population growth, urban water demand is expected to increase significantly, as well as the environmental and economic costs required to supply it. Rainwater harvesting (RWH) systems can play a key role in helping cities meet part of their water demand as an alternative to conventional water abstraction and treatment. This paper presents an environmental and economic analysis of RWH systems providing households with water for laundry purposes in a life cycle thinking perspective.MethodsEight urban RWH system scenarios are defined with varying population density and storage tank layout for existing buildings. Storage tank volume required is calculated using Plugrisost software, based on Barcelona rainfall and catchment area, as well as water demand for laundry, since laundry is a fairly constant demand of non-potable water. Life cycle assessment (LCA) and life cycle costing (LCC) methodologies are applied for this study. Environmental impacts are determined using the ReCiPe 2008 (hierarchical, midpoint) and the cumulative energy demand methods. Net present value (NPV), internal rate of return (IRR), and payback (PB) time were used in LCC. Savings from laundry additives due to the difference in water hardness was, for the first time, included in a RWH study.Results and discussionLCA results indicate that the best scenario consists of a 24-household building, with the tank spread on the roof providing up to 96% lower impacts than the rest of scenarios considered. These results are mainly due to the absence of pumping energy consumption and greater rainwater collection per cubic meter of built tank capacity. Furthermore, avoided environmental impacts from the reduction in detergent use are more than 20 times greater than the impacts generated by the RWH system. LCC indicates that RWH system in clusters of buildings or home apartments offer up to 16 times higher profits (higher NPV, higher IRR, and lower PB periods) than individual installations.ConclusionsLCA and LCC present better results for high-density scenarios. Overall, avoided environmental and economic impacts from detergent reduction clearly surpass environmental impacts (in all categories except terrestrial acidification) and economic cost of the RWH system in most cases (except two scenarios). Another important finding is that 80% of the savings are achieved by minimizing detergent and fabric softener by using soft rainwater; and the remaining 20% comes from replacing the use of tap water.