Modeling of Electrokinetic Remediation Combining Local Chemical Equilibrium and Chemical Reaction Kinetics

A mathematical model for reactive-transport processes in porous media is presented. The modeled system includes diffusion, electromigration and electroosmosis as the most relevant transport mechanism and water electrolysis at the electrodes, aqueous species complexation, precipitation and dissolution as the chemical reactions taken place during the treatment time. The model is based on the local chemical equilibrium for most of the reversible chemical reactions occurring in the process. As a novel enhancement of previous models, the local chemical equilibrium reactive-transport model is combined with the solution of the transient equations for the kinetics of those chemical reactions that have representative rates in the same order than the transport mechanisms. The model is validated by comparison of simulation and experimental results for an acid- enhanced electrokinetic treatment of a real Pb-contaminated calcareous soil. The kinetics of the main pH buffering process, the calcite dissolution, was defined by a simplified empirical kinetic law. Results show that the evaluation of kinetic rate entails a significant improvement of the model prediction capability.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Part of this work was supported financially by the European Commission within the project LIFE12 ENV/IT/442 SEKRET “Sediment electrokinetic remediation technology for heavy metal pollution removal”. Paz-Garcia acknowledges the financial support from the “Proyecto Puente - Plan Propio de Investigación y Transferencia de la Universidad de Málaga”, code: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the financial support from the University of Malaga through a postdoctoral contract

Influence of chemical reaction kinetics on electrokinetic remediation modelling results

A numerical model describing transport of multiple species and chemical reactions during electrokinetic treatment is presented. The transport mechanisms included in the model were electromigration and electroosmosis. The chemical reactions taken into account were water electrolysis at the electrodes, aqueous species complexation, precipitation, and dissolution. The model was applied to simulate experimental data from an acid-enhanced electrokinetic treatment of a Pb-contaminated calcareous soil. The kinetics of the main pH buffering process (i.e., calcite dissolution) was taken into account and its time-dependent behavior was described by a rate law. The influence of kinetics was evaluated by comparing the results from a set of simulations in which calcite dissolution was implemented considering thermodynamic equilibrium and another set in which the same reaction was described by the rate law. The results show that the prediction capability of the model significantly improves when the kinetic rate is taken into account.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Effectiveness of conventional drinking water treatment in the removal of polycyclic aromatic hydrocarbons

The presence of recalcitrant organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) in aquatic environments poses a threat to the human health. According to recent studies, PAHs, such as benz[a]anthracene and phenanthrene, has been found in untreated drinking water. Hence, the removal of these contaminants through conventional treatment processes should be carefully evaluated. In this work, levels of selected PAHs in drinking water have been monitored during conventional treatment processes. The simulation of a full-scale Potable Water Treatment Plant (PWTP) located in the south of Spain was carried out using jar tests, a widely accepted tool in water treatment. The quantification of PAH concentration in drinking waterwas carried out using gas chromatography coupled with mass spectrometry.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Removal of polycyclic aromatic hydrocarbons (PAHs) in conventional drinking water treatment processes

Authors acknowledge the Central Laboratory of EMASA for the facilities provided to carry out the research. M. Villen-Guzman acknowledges the postdoctoral fellowship obtained from Universidad de Malaga, Spain. Funding for open access charge: Universidad de Malaga / CBUA, Spain.The presence of polycyclic aromatic hydrocarbons (PAHs) in water poses a serious threat to the human health due to their toxic effects. Therefore, the removal of these compounds from drinking water in Potable Water Treatment Plants (PWTPs) should be evaluated and optimized to assure the quality of water intended for human consumption. In this work, changes in PAHs levels during drinking water treatment processes have been monitored to evaluate the effectiveness of conventional processes in the removal of these recalcitrant pollutants. Several chemical treatment methods based on the addition of KMnO4, FeCl3 and NaClO were evaluated through jar tests. The analysis of PAH content of aqueous samples was carried out by gas chromatography coupled with mass spectrometry. The highest removal efficiency, over 90%, was obtained for benzo(a)anthracene, benzo(a) pyrene and dibenzo(a,h)anthracene. The most recalcitrant compounds to degradation were fluorene, anthracene, phenanthrene and flouranthene with reduction rates between 45 and 57%. The conventional treatment processes assessed have been proved to be effective reducing the PAH below the legal limits of drinking water quality. The definition of a parameter based on chemical properties of PAHs, i.e., sorption capacity and energy required to remove an electron, enabled the prediction of removal rate of pollutants which represents a valuable information for the plant operation.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Technical analysis of CO2 capture pathways and technologies

The reduction of CO2 emissions to minimize the impact of the climate change has become a global priority. The continuous implementation of renewable energy sources increases energy efficiency, while the reduction of CO2 emissions opens new options for carbon capture technologies to reduce greenhouse gases emissions. The combination of carbon capture with renewable energy balancing production offers excellent potential for fuels and chemical products and can play an essential role in the future energy system. This paper includes a critical review of the state of the art of different CO2 capture engineering pathways and technologies including a techno-economics analysis and focusing on comparing these technologies depending on the final CO2 application. The current cost for CO2 capture is in the range of 60–110 USD/t, likely to halve by 2030. This review offers technical information to select the most appropriate technology to be used in specific processes and for the different carbon capture pathways, i.e., Pre-combustion, Post-Combustion and Direct Air Capture. This comparison includes the CO2 capture approach for biomethane production by biogas upgrading to substitute fossil natural gas and other alternatives fuels production routes which will be introduces in future works performed by this review authors.Funding for open access charge: Universidad de Málaga / CBUA

Anaerobic co-digestion of pear residues and sewage sludge using a CSTR digester. Influence of the feed procedure

Anaerobic co-digestion of pear residues with sewage sludge is feasible. Important differences are obtained from the two feed regimes tested, with better results for the so-called continuous feed. The organic loading rate (OLR) is the important parameter for the methane productionUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Life cycle assessment of aluminium cans and glass bottles

In this work, we present a simplified LCA on two commom products: an aluminum can and a glass bottle, both containing the same amoung of beverage (1/3 L of beer). The work presented here seeks to find out which option would be less harmful to the environment by studying the CO2 emissions produced by each container using a combined the cradle-to-cradle and cradle-to-grave approach, based on the current recycling rates in Spain. The functional unit is set to 1 m3 of beer, and the target consumer is someone purchasing beer at a supermarket. Therefore, according to the current waste management system in Spain, glass bottles are considered not reusable: This means that they are either disposed to landfill or deposited to the glass container for recycling. Recycling of glass would involve using the glass as raw material to produced new bottles. The free to use database IDEMAT has been used in the work presented here to obtain the data necessary for the Life Cycle Inventory. The results indicate that purchasing beer in aluminiun cans have a lower environmental impact than non-reusable glass bottles. The main reason related to this results are the lower transport emissions related to the cans due to the lower weight. This means that, for the same amount of beer, the energy required to transport the bottles is higher than the cans, and therefore the CO2 emissions are also higher. Additionally, aluminium is 100% and infinitely recyclable, while glass bottles made of recycled glass still need a certain intake of new raw material (of around 40%). The results presented here do not contemplate the posiblity to clean and reuse the bottles, which is expected to have a lower environmental footprint that the two scenarios discussed here.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

New Perspectives for Electrodialytic Remediation

Electrodialytic remediation has been widely used for the recovery of different contaminants from numerous matrices, such as, for example, polluted soils, wastewater sludge, fly ash, mine tailing or harbour sediments. The electrodialytic remediation is an enhancement of the electrokinetic remediation technique, and it consists of the use of ion-exchange membranes for the control of the acid and the alkaline fronts generated in the electrochemical processes. While the standard electrodialytic cell is usually built with three-compartment configuration, it has been shown that for the remediation of matrices that require acid environment, a two-compartment cell has given satisfactory removal efficiencies with reduced energy costs. Recycling secondary batteries, with growing demand, has an increasing economic and environmental interest. This work focusses on the proposal of the electrodialytic remediation technique as a possible application for the recycling of lithium-ion cells and other secondary batteries. The recovery of valuable components, such as lithium, manganese, cobalt of phosphorous, based on current recycling processes and the characterization of solid waste is addressed.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Electrodialytic Recovery of Cobalt from Spent Lithium-Ion Batteries

Contribución en congreso científicoRecycling lithium-ion batteries has an increasing interest for economic and environmental reasons. Disposal of lithium-ion batteries imposes high risk to the environment due to the toxicity of some of their essential components. In addition to this, some of these components, such as cobalt, natural graphite and phosphorus, are included in the list of critical raw materials for the European Union due to their strategic importance in the manufacturing industry. Therefore, in the recent years, numerous research studies have been focused on the development of efficient processes for battery recycling and the selective recuperation of these key components. LiCoO2 is the most common material use in current lithium-ion batteries cathodes. In the current work, an electrodialytic method is proposed for the recovery of cobalt from this kind of electrode. In a standard electrodialytic cell, the treated matrix is separated from the anode and the cathode compartments by means of ion-exchange membranes. A cation-exchange membrane (CEM) allows the passage of cations and hinders the passage of anions, while the behaviour of anion-exchange membrane (AEM) does the opposite. A three-compartment electrodialytic cell has been designed and assembled, as depicted in the figure. In the central compartment, a suspension of LiCoO2 is added. Different extracting agents, such as EDTA, HCl and HNO3, are tested to enhanced the dissolution and the selective extraction of the target metal. Dissolved cobalt-containing complexes migrate towards the cathode or the anode compartments depending on the ionic charge of the complexes. While cobalt extraction via extracting agents is an expensive treatment, as it requires the constant addition of chemicals, an efficient electrodialytic cell could allow the recirculation of the extracting agents and the economical optimization of the process.This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 778045. Paz-Garcia acknowledges the financial support from the University of Malaga, project: PPIT.UMA.B5.2018/17. Villen-Guzman acknowledges the funding from the University of Malaga for the postdoctoral fellowship PPIT.UMA.A.3.2.2018. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Effect of NaHCO3 addition on the anaerobic co-digestion of fruit and vegetable waste and sewage sludge performance

Digestion of FVW residues with sewage sludge is feasible as long as the FVW to sludge ratio fed to the batch digester is not too large. The pH is the main variable determining the reactor performance and can be controlled by NaHCO3 addition.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech