Cleomar Reginatto

Review of Nanotechnology for Soil and Groundwater Remediation: Brazilian Perspectives

The soil remediation field is still in development in Brazil. Currently, it is not known how many contaminated sites exist across the country; however, due to the country’s large size and its extensive urbanization and industrialization, it can be postulated that the number of contaminated sites must be very high. To remediate these sites, new sustainable technologies should be identified and evaluated. A technology that was born in the 1990s in the USA, and has been fairly investigated, is the use of nanoparticles (NPs) to degrade contaminants in soils and groundwater. This study aims to present a bibliographic review of nanotechnology application to remediation of soils and groundwater, as well as assess the potential of conducting research in this field in Brazil. This paper first presents an overview of the number of contaminated areas identified in the USA and Europe. The basic concepts of nanomaterials followed by classification, synthesis, and characterization of nanomaterials are explained. The main types of contaminants for which the technique was already applied as well as the chemical reactions between them and NPs are presented. The issues related to delivery and migration of NPs in the porous media is discussed. Concerns regarding the toxicity of nanomaterials are discussed. The in situ applications of nanomaterials for contaminated site remediation are presented. It is concluded that the issues involving remediation of soils and groundwater are site specific and it is not possible to directly transfer knowledge gained from sedimentary soils of temperate climates for residual soils found in tropical and subtropical climate regions. The research on nanotechnology for site remediation in Brazil has just begun, and more efforts are required from the technical and academic professionals to develop nanotechnology as practical technology for the remediation of contaminated sites.

Influence of physicochemical factors on biodiesel retention in clayey residual soil.

AbstractSoil can naturally attenuate contamination, depending on its interaction with contaminants. Soils can delay the spread of the contaminant plume and even reduce the bioavailability of the contaminant because of their contaminant retention capacity. The retention capacity may be influenced by several physicochemical factors of both the soil and the contaminant. The aim of this study was to assess the retention capacity of a clayey, basaltic residual soil to an organic contaminant (soybean biodiesel) under different variable conditions, such as moisture content, void ratio, and presence or absence of biostimulation nutrients, specifically nitrogen (N), phosphorus (P), and potassium (K). Experiments were conducted using 100-g samples of dry soil under different void ratios (1.14, 1.24, and 1.34) and different moisture contents (15, 25, and 35%). Two series of experiments were conducted: one in the absence of nutrients and another in the presence of nutrients. The soil samples were initially sterilized...

Biorremediação de um solo argiloso contaminado com uma mistura de diesel e biodiesel através da bioventilação

O crescente consumo de combustiveis fosseis gera a necessidade de buscar fontes alternativas ambientalmente mais adequadas, como e o caso do biodiesel, em misturas com o diesel. Porem essa mistura torna-se um provavel contaminante ambiental. A bioventilacao e uma tecnica de biorremediacao que envolve apenas a insercao de ar no meio, para estimular a atividade aerobia dos microrganismos e surge como uma alternativa aos metodos convencionais de remediacao. O objetivo deste trabalho foi avaliar a biorremediacao ex situ de um solo argiloso contaminado com uma mistura B20 utilizando a bioventilacao. Os ensaios foram realizados em biorreatores de PVC, e 4% de contaminante, em relacao a massa de solo seco. Foram testadas tres vazoes de ar (2, 4 e 6 L/min), em tres intervalos de tempo distintos (1h a cada 24h, 36h e 48h), alem do controle. A degradacao do contaminante foi avaliada atraves da determinacao da fracao residual, extraido por ultrassom, em 3 tempos (15, 30 e 60 d). A maior degradacao aos 60 dias, foi obtida para a velocidade de ar de 6 L/min aplicado diariamente, com 86% de degradacao, demonstrando-se ser a bioventilacao uma tecnica de biorremediacao promissora para o tratamento de solos argilosos contaminados com mistura B20.

Toxicity Evaluation of Nano-Zero Valent Iron to Soil Indigenous Microorganisms

The objective of this study was to evaluate the toxicity of nZVI to the indigenous microorganisms of the soil. The toxicity of nZVI was assessed by the CO2 production for the soil native microorganisms. Different concentrations of nZVI were added to the soil (0, 4, 15 and 50 g/kg) for further analysis of the microbiological activity. For a better interpretation of toxicity effects, was used glucose (g/kg) as a carbon source. As soil mixtures, nZVI and glucose were inserted into sealed vials for an evaluation of the microbiological activity. The quantification of CO2 produced by the indigenous microbes respiration was performed by stoichiometry, using NaOH to absorb the gas and using HCl to determine the concentration. The analyzes were performed every 02 days, until a total monitoring time of 40 days. It was observed that at a concentration of 50 g/kg it has not released any carbon dioxide, demonstrating a maladaptation of the microorganisms under these conditions. The nZVI concentrations of 4 and 15 g/kg showed an increase of CO2 production, indicating an adaptation of the microorganisms as available conditions. Thus, the application of nZVI as remediation technology can be performed up to concentrations of 15 g/kg without causing damage to native soil microorganisms. However, applications above these may cause toxic and/or inhibitory effects to the microbes, restricting a possible combination of nano and bioremediation.

Remediation Technologies Applied in Polluted Soils: New Perspectives in This Field

There are millions of contaminated areas in the world that need to be remediated so that they can be reused without risk to health. This article presents the main remediation techniques applied to soils, sediments, and groundwater. These technologies can be classified as five processes, i.e. physical, chemical, biological, thermal, and combined. This article also offers a method for choosing the best technique to remediate a place, called sustainable remediation. An evaluation of the toxicity of remediation techniques is presented. Finally, a summary of remediation practice in China is discussed, and the main challenges of future remediation research are presented. The following concluding observations can be reached: the development of a software for the selection of soil remediation technologies can be very helpful to professionals in the field. However, it is important to note that each remediation technology has its own characteristics, limitations, advantages and disadvantages, and no universal method can satisfy all needs.

ATENUAÇÃO NATURAL EM SOLO RESIDUAL DE BASALTO CONTAMINADO COM MISTURAS DE DIESEL E BIODIESEL

Os biocombustiveis (biodiesel) quando usados em misturas com combustiveis fosseis (diesel) tornando-se potenciais contaminantes de solos. A atenuacao natural devido ao baixo custo e pouca intervencao nas condicoes naturais da area e uma tecnica competitiva na descontaminacao de solos. O objetivo deste trabalho foi avaliar a degradacao, em laboratorio, em solo residual de basalto contaminado com misturas de diesel e biodiesel. O solo foi contaminado na proporcao de 4% em relacao a massa de solo seco e compactado na densidade natural de 1,6 g/cm³. A umidade final do solo, apos a contaminacao, foi de 34%. Foram utilizados seis diferentes percentuais de biodiesel junto ao diesel: B0, B5, B12,5, B20, B50 e B100 moldados em biorreatores em duplicata. Amostras foram coletas apos 105 dias do inicio do ensaio e essas foram analisadas pelo metodo de Soxhlet e cromatografia gasosa. Os resultados demonstraram que as misturas com maior porcentagem de biodiesel apresentaram maior degradacao. Isso demonstra que, alem do biodiesel ser mais biodegradavel que o diesel, ele tambem auxilia na degradacao das misturas fosseis. Ate 12,5% de biodiesel na mistura nao houve diferenca significativa na degradacao. Palavras-chave: Biorremediacao, Soxhlet, Cromatografia Gasosa, Contaminacao de Solos. ABSTRACT Biofuels (biodiesel) when used in mixtures with fossil fuels (diesel oil) become potential soil contaminants. The natural attenuation due to the low cost and little intervention in the natural conditions of the area is a competitive technique in soil decontamination. The aim of this study was to evaluate the degradation in laboratory of a residual soil from basalt contaminated with diesel and biodiesel mixtures. The soil was contaminated with a proportion of 4% relating to the mass of dry soil and compacted in the natural density of 1.6 g/cm³. The final soil moisture after contamination was 34%. It was used six different percentages of biodiesel called: B0, B5, B12.5, B20, B50, and B100. The mixture were molded in bioreactors in duplicate. Samples were collected after 105 days and they were analyzed by the Soxhlet extraction method and gas chromatography. The results showed that mixtures with higher percentage of biodiesel are more degradable. This shows that besides biodiesel being more biodegradable than diesel, it also assists in the degradation of fossil mixtures. To up to 12,5% of biodiesel in the mixture there was no significant difference in degradation. Keywords: Bioremediation, Soxhlet, Gas chromatography, Soil Contamination.