RESUMO
Nanoscale zero valent iron (nZVI) is globally the main nanomaterial used in contaminated site remediation. This study aims to evaluate the sustainability of using nZVI in the nanoremediation of contaminated sites and to determine the factors that affect the sustainability of the use of nZVI in remediation. Five case studies of nZVI use on a pilot scale were selected. Life cycle analysis tools were used to evaluate environmental, economic, social impacts, and sustainability. The functional unit of the life cycle analyses was 1.00 m3 of remediated soil and groundwater. Case study of Brazil was the least sustainable, while case study of United States was the most sustainable. Only the modification of the functional unit results in variations in the sustainability index. Different factors influence the sustainability of nZVI in remediation, the main factor being the amount of nZVI used in the processes. Finally, this work contributes significantly to the state-of-the-art sustainable use of nZVI in remediation. This is a pioneering study in the detailed and comprehensive assessment of the sustainability of the use of nZVI in remediation. Through the analysis of case studies, it is possible to determine the main factors that influence the sustainability of the nZVI remediation life cycle.
Assuntos
Recuperação e Remediação Ambiental , Água Subterrânea , Ferro , Poluentes do Solo , Poluentes Químicos da Água , Água Subterrânea/química , Recuperação e Remediação Ambiental/métodos , Ferro/química , Poluentes do Solo/química , Poluentes Químicos da Água/química , Solo/química , Brasil , Nanopartículas Metálicas/químicaRESUMO
In this article, the optimization of the specific urease activity (SUA) and the calcium carbonate (CaCO3) using microbially induced calcite precipitation (MICP) was compared to optimization using three algorithms based on machine learning: random forest regressor, artificial neural networks (ANNs), and multivariate linear regression. This study applied the techniques in two existing response surface method (RSM) experiments involving MICP technique. Random forest-based models and artificial neural network-based models were submitted through the optimization of hyperparameters via cross-validation technique and grid search, to select the best-optimized model. For this study, the random forest-based algorithm is aimed at having the best performance of 0.9381 and 0.9463 in comparison to the original r2 of 0.9021 and 0.8530, respectively. This study is aimed at exploring the capability of using machine learning-based models in small datasets for the purpose of optimization of experimental variables in MICP technique and the meaningfulness of the models by their specificities in the small experimental datasets applied to experimental designs. This study is aimed at exploring the capability of using machine learning-based models in small datasets for experimental variable optimization in MICP technique. The use of these techniques can create prerogatives to scale and mitigate costs in future experiments associated to the field.
Assuntos
Redes Neurais de Computação , Algoritmo Florestas Aleatórias , Algoritmos , Aprendizado de Máquina , Carbonato de CálcioRESUMO
Nanoscale zero-valent iron (nZVI) is the main nanomaterial used in environmental remediation processes. However, as with any remediation technique, the production and the use of nanomaterials can also cause environmental, economic, and social impacts. Thus, the present study investigated the social life cycle analysis (S-LCA) of nZVI production methods applied in environmental remediation. Three production methods of nZVI were selected for analysis: milling, reduction with sodium borohydride, and reduction with hydrogen gas. The social life cycle analysis was developed based on the ISO 14040 standard steps. Limits of the S-LCA system involve the stages of raw material extraction and manufacturing when not considering the use of nZVI postproduction. The analysis of social impact was conducted considering the involved stakeholders, through the application and improvement of an existing methodology and through the following procedures: characterization of social indicators according to a normalized scale, identification of the normalization factor for the indicators, employment of a social questionnaire, calculation of the total points in each impact subcategory (midpoint), calculation of the total points in the impact categories (endpoint), and calculation of the Social Index. The three production methods of nZVI result in significantly equal Social Indices. All methods were classified as socially sustainable according to the implemented methodology. The sensitivity analysis demonstrates the results dependent with the geographic location of the inventory data, while changes in the weighting can affect the Social Index results. Overall, this study significantly contributed to the state-of-the-art application of S-LCA in studies using nanomaterials; however, several limitations were also observed, and thus, steps for future development were suggested to future researches. In addition, this study improved the S-LCA methodology which can be used to assess the social impact of any product.
Assuntos
Recuperação e Remediação Ambiental , Ferro , Animais , Hidrogênio/análise , Ferro/análise , Estágios do Ciclo de VidaRESUMO
The purpose of this paper is to analyse the global Sales and Operations Planning (S&OP) process and investigate the steps to support consolidated business planning in worldwide operations and large-scale supply chains. The paper conducts a case study at a multinational manufacturing company applying an abductive approach. It combines the deductive logic from theory and the inductive logic from field observation in an attempt to elaborate further on theory on global S&OP. The analysis is structured and guided by a novel framework for global S&OP, which is developed based on the theoretical background and the case study findings. The research findings characterise the S&OP process for global operations and identify challenges related to the need to synchronise the subsidiaries' S&OP efforts worldwide to deal with different contingencies of these subsidiaries, and to manage and analyse a large amount of information gathered. The research reveals how the subsidiaries' performance is analysed by top executives along the global S&OP process, feeding strategic initiatives in the organisation and identifying business opportunities like benchmarking among subsidiaries, synergies with other management practices, and global gains. This paper offers a novel investigation of the global steps on S&OP in a real-life setting, offering a well-documented characterisation of the process that goes beyond the traditional local approach. Moreover, it is the first study to reveal challenges and expected outcomes of such a global perspective for S&OP. The theoretical advancements of S&OP research offered herein aid scholars, opening avenues for middle-range theorising, highlighting the cross-disciplinary nature of the domain, and discussing the use of concepts from related disciplines like Economics, Psychology, and Information Systems. The research findings can also assist executives, especially from multinational manufacturers, in their efforts to consolidate global planning.
Assuntos
Comércio/organização & administração , Internacionalidade , Modelos EconômicosRESUMO
We aimed to produce simultaneously biosurfactants and lipases in solid state fermentation (SSF) using Aspergillus niger, followed by the use of the fermented media on the bioremediation of oily contaminated soil, in order to valuate agro industrial residuals and reduce the contamination. The biocompounds were produced using wheat bran and corncob (80:20), 5% of soybean oil and 0.5% of sugar cane molasses in SSF for 4 d, producing 4.58 ± 0.69 UE of emulsifying activity and 7.77 ± 1.52 U of lipolytic activity. This fermented media was used in the bioremediation of a 20% biodiesel contaminated soil, evaluating for 90 d microbial growth, contaminant degradation, and production of lipases and biosurfactants in soils. Six experimental strategies (natural attenuation; biostimulation + bioaugmentation + biocompounds; biostimulation + biosurfactant; biocompounds extract; biostimulation; adsorption of contaminant) were realized. The highest degradation of contaminant was verified in 90 d, of 74.40 ± 1.76%, and the production of biosurfactants and lipases in situ in the soil was found in 30 d (6.02 ± 0.24% of reduction in surface tension and 6.62 ± 0.17 UL of lipid activity in soil) for the same experiment (biostimulation + bioaugmentation + biocompounds). The addition of biostimulation + biosurfactant promotes higher biodegradation (66.00 ± 0.92%) of the contaminant than the biocompounds extract (59.58 ± 0.34%). The use of a solid fermented culture medium containing both biocompounds was feasible for the treatment of contaminants, demonstrating the potential for environmental application without the need for purification processes.
Assuntos
Petróleo , Poluentes do Solo , Biodegradação Ambiental , Biocombustíveis , Solo , Microbiologia do Solo , Poluentes do Solo/análiseRESUMO
The contamination of soils by oily compounds has several environmental impacts, which can be reversed through bioremediation, using biosurfactants as auxiliaries in the biodegradation process. In this study, we aimed to perform ex situ bioremediation of biodiesel-contaminated soil using biosurfactants produced by Bacillus methylotrophicus. A crude biosurfactant was produced in a whey-based culture medium supplemented with nutrients and was later added to biodiesel-contaminated clayey soil. The produced lipopeptide biosurfactant could reduce the surface tension of the fermentation broth to 30.2 mN/m. An increase in the microbial population was observed in the contaminated soil; this finding can be corroborated by the finding of increased CO2 release over days of bioremediation. Compared with natural attenuation, the addition of a lower concentration of the biosurfactant (0.5% w/w in relation to the mass of diesel oil) to the soil increased biodiesel removal by about 16% after 90 days. The added biosurfactant did not affect the retention of the contaminant in the soil, which is an important factor to be considered when applying in situ bioremediation technologies.
Assuntos
Petróleo , Poluentes do Solo , Bacillus , Biodegradação Ambiental , Biocombustíveis , Argila , Solo , Microbiologia do Solo , Poluentes do Solo/análise , TensoativosRESUMO
This study investigated the reduction of hexavalent chromium (Cr(VI)) in a clayey residual soil using nanoscale zero-valent iron (nZVI). Five different ratios between nZVI and Cr(VI) were tested in batch tests (1000/11; 1000/23; 1000/35; 1000/70, and 1000/140 mg/mg) with the soil. With the selected proportion resulting best efficiency, the column tests were conducted, with molded specimens of 5 cm in diameter and 5 cm in height, with different nZVI injection pressures (10, 30, and 100 kPa). The soil was contaminated with 800 mg/kg of Cr(VI). The Cr(VI) and Cr(III) analyses were performed following the USEPA 3060A and USEPA 7196A standards. The results show that the reduction of Cr(VI) is dependent on the ratio between nZVI and Cr(VI), reaching 98% of efficiency. In column tests, the pressure of 30 kPa was the most efficient. As pressure increased, contaminant leaching increased. The permeability decreased over time due to the gradual increase in filtration and formation of oxyhydroxides, limiting nZVI mobility. Overall, nZVI is efficient for soil remediation with Cr(VI), but the injection process can spread the contaminated if not properly controlled during in situ application.
Assuntos
Cromo/química , Cromo/toxicidade , Argila/química , Recuperação e Remediação Ambiental/métodos , Ferro/química , Nanotecnologia/métodos , Poluentes do Solo/toxicidadeRESUMO
Contaminated clay soils pose problems to public health and the environment in several parts of the world. Very little is known about the transport of decontaminating agents used in remediation process under natural, undisturbed conditions. Nanomaterials, especially those made of nanoscale zero-valent iron (nZVI), have been most frequently used for remediation of contaminated soils because of their higher reactivity, lower toxicity, and lower cost than other metallic nanoparticles. Even though the nanoparticle size is smaller than soil pores, clogging may occur over time due to agglomeration of nanoparticles, which could reduce the soil's natural permeability and thereby cause filtration of the nanoparticles. The use of a stabilizer in the nanoparticles can modify the reactivity but improves their mobility in the soil system. Thus, the objective of this work was to evaluate the hydraulic conductivity of residual clay soil under the injection of different types and concentrations of nZVI with and without surfactant stabilizer (NANOFER 25, NANOFER 25S, and NANOFER STAR in powder at 1 g/L, 4 g/L, 7 g/L, and 10 g/L concentrations), and to model transport of these nZVI suspensions in this soil system. Undisturbed cylindrical soil samples collected from the field were used, and hydraulic conductivity tests were performed using a column apparatus. The results showed that the presence of the stabilizer in the nZVI influenced the nanoparticles' mobility. The nZVI concentrations of 1 and 4 g/L did not affect the natural soil hydraulic conductivity. However, higher concentrations reduced the hydraulic conductivity value, which retarded the migration of nZVI as reflected in the value of filtration parameter.
Assuntos
Recuperação e Remediação Ambiental , Nanopartículas Metálicas , Poluentes do Solo , Argila , Ferro/química , Nanopartículas Metálicas/química , Solo , Poluentes do Solo/análise , Poluentes do Solo/químicaRESUMO
As sustainable remediation methods do not yet have a consolidated approach, a detailed assessment of the level of satisfaction for sustainability prospects is necessary. So, this study aims to evaluate the sustainability level of sustainable remediation methods according to the visions of decision makers in this field, in order to propose an optimized method that best represents its approach. We considered eight methods applied to sustainable remediation and nine decision criteria for evaluation. The analytical hierarchy process (AHP) of multi-criteria decision analysis (MCDA) was applied to judge and weigh the criteria by stakeholders. These weights were used to calculate the degrees of sustainability for all the methods, to classify these within a ranking, and to optimize the one that obtained the best performance. The results indicated that when the criteria were weighted, the criterion (C7), protection of human health and the environment in general, obtained the best placement, and the degree of sustainability achieved by each method indicates that ITRC (Interstate Technology and Regulatory Council) had the best performance. Finally, the proposal method resulted in an explicit approach of all the considered criteria. This article presents a new approach compared with those already applied in this context and provides more robust resources to examine to what extent the methods integrate the premises of sustainable remediation. Graphical Abstract .
Assuntos
Conservação dos Recursos Naturais/métodos , Recuperação e Remediação Ambiental , Tomada de Decisões , Técnicas de Apoio para a Decisão , Humanos , Projetos de PesquisaRESUMO
In recent years, the broader environmental impacts of remediation that arise from different remediation activities has drawn attention of practitioners, remediation design professionals and academicians to evaluate the net environmental benefit of environmental remediation projects. The main objective of this paper is to describe the Quantitative Assessment of Life Cycle Sustainability (QUALICS) framework, a new tool developed to strengthen decision-making in the selection of sustainable remedial technologies for the clean-up of contaminated sites. The proposed framework is a combination of two multi-criteria evaluation methods namely, the Integrated Value Model for Sustainable Assessment (MIVES) and Analytic Hierarchy Process (AHP). The QUALICS uses a multi-criteria assessment framework to support decision-making in remediation projects. A description of the methodology adopted for sustainability assessment of alternative remedial strategies using QUALICS framework is presented in this study. In addition, a case study is discussed to demonstrate the application of the QUALICS framework for the sustainability assessment of different remediation options for clean-up of a contaminated site. The case study involves sustainability assessment of different remediation options namely, electrokinetic remediation (EKR), excavation/disposal, and phytoremediation for remediation of a contaminated site. A sensitivity analysis was also performed for the EKR option by varying different parameters including electrode materials, energy source, electrolyte used, to analyze their influence on the sustainability of the alternative remedial options. The proposed framework can also be applied to any project in general to quantify and compare the sustainability indices of each of the alternative options considered and thereby identify the most sustainable option.