Sogaard Chemistry of Advanced Environmental Purification Processes of Water

Fundamentals and Applications
1. Auflage 2014
ISBN: 978-0-08-093240-8
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 360 Seiten

Chemistry of Advanced Environmental Purification Processes of Water covers the fundamentals behind a broad spectrum of advanced purification processes for various types of water, showing numerous applications through worked examples. Purification processes for groundwater, soil water, reusable water, and raw water are examined where they are in use full-scale, as a pilot approach, or in the laboratory. This book also describes the production of ceramic particles (nanochemistry) and materials for the creation of filtration systems and catalysts that are involved. - Uses chemistry fundamentals to explain the mechanisms behind the various purification processes - Explains in detail process equipment and technical applications - Describes the production of ceramic particles and other new materials applicable to filtration systems - Includes worked examples

1976 MSc. Chemistry and Physics, specialization in Physical Chemistry, Aarhus University, Denmark1976-1978 Medical Representative, Roche A/S, Denmark1978-1984 Lecturer, Physics and Chemistry, Teacher Training College, Toender Statsseminarium, Toender, Denmark1983-1990 Lecturer, Physics and Chemistry, Aalborg Katedralskole (High School), Aalborg, Denmark 1990-1995 Associate Professor in Fundamental and Applied Chemistry, Engineering College Esbjerg Teknikum, Esbjerg, Denmark1995-2013 Associate Professor in Chemical Engineering, Aalborg University Esbjerg, Denmark2013 Professor mso in Chemical Engineering, Section of Chemical Engineering, Department of Chemistry and Biotechnology, Aalborg University Esbjerg, Denmark

Autoren/Hrsg.

Sogaard, Erik

Leseproben

Chapter 2 In situ Chemical Oxidation
The Mechanisms and Applications of Chemical Oxidants for Remediation Purposes
Project leaderLars R.Bennedsen     Rambøll A/S, Vejle, Denmark Abstract
Contamination of the subsurface by persistent organic contaminants remains a significant problem, even after decades of research on remediation. First, approaches focused on excavation, pump and treat via activated carbon, bioremediation, and natural attenuation. In the 1990s the first reports on in situ chemical oxidation (ISCO) were published, which is a technique involving the introduction of chemical oxidants into the subsurface in order to transform contaminants into less harmful substances. Hydrogen peroxide was the first chemical oxidant investigated and used in full scale. Shortly after ozone and permanganate came into use. In the past few years persulphate has provided yet another option. In this chapter, the chemical reactions of the most common chemical oxidants used in ISCO are reviewed and the applicability of the two most relevant modified Fenton's reagent and activated sodium persulphate are demonstrated using the Kærgaard Plantation megasite in Denmark as case study. This site represents one of the most difficult remediation challenges in Scandinavia and, therefore, regulatory agencies have been evaluating remediation techniques for source area remediation. Keywords
Activated persulphate (ASP)Chlorinated solventsContaminationGround waterIn situ chemical oxidation (ISCO)Modified Fenton's reagent (MFR)PharmaceuticalsSite remediation Contamination of the subsurface by persistent organic contaminants remains a significant problem, even after decades of research on remediation technologies (Watts et al., 1999b, Watts and Teel, 2005). First, approaches focused on excavation, pump and treat via activated carbon, bioremediation, and natural attenuation. In the 1990s the first reports on in situ chemical oxidation (ISCO) were published, which is a technique involving the introduction of chemical oxidants into the subsurface in order to transform contaminants into less harmful substances. Hydrogen peroxide was the first chemical oxidant investigated and used in full scale. Shortly thereafter ozone and permanganate came into use. In the past few years persulphate has provided yet another option. In this chapter, the chemical reactions of the most common chemical oxidants used in ISCO are reviewed and the applicability of the two most relevant, modified Fenton's reagent (MFR) and activated sodium persulphate (ASP), are demonstrated using the Kærgaard Plantation megasite in Denmark as case study. This site represents one of the most difficult remediation challenges in Scandinavia and, therefore, regulatory agencies have been evaluating remediation techniques for source area remediation. Introduction
Soil and Ground Water Contamination
Freshwater comprises only 3% of all water on the Earth and around 20% of this small fraction occurs as ground water, which is a critical resource throughout the world because of its use as drinking water, for agricultural applications, for irrigation of crops and for industrial activities. Ground water serves as a significant source of drinking water ranging from 15% in Australia to 75% in Europe (Morris et al., 2003). In Denmark close to 100% of the drinking water originates from ground water. Today soil and ground water contamination is a widespread and challenging problem threatening ground water resources throughout the world. The contamination originates from introduction of xenobiotic chemicals to the environment or from naturally occurring sources and the most common chemical contaminants found in the environment are petroleum hydrocarbons, solvents, coal tar, heavy metals and pesticides. An overview of contaminants affecting soil and ground water in Europe is given in Figure 2.1. The contamination originates from a broad range of sources with landfills, above/underground storage tanks, septic systems, dry cleaners and industrial facilities being among the frequent sources; see more details in Figure 2.2. In North America and Western Europe most countries have a legal framework to identify and deal with these issues. In the United States alone there are estimated to be in excess of 200,000 sites requiring some form of remediation (ITRC, 2005). In Europe this number is approximately 250,000 sites in the European Environmental Agency member countries and the number is expected to grow. Potentially polluting activities are estimated to have occurred at nearly 3 million sites in Europe (including the 250,000 sites already mentioned) and investigation is needed to establish whether remediation is required. If current investigation trends continue, the number of sites needing remediation will increase by 50% in 2025. By contrast, more than 80,000 sites have been cleaned up in the past 30 years in the countries where data on remediation is available (European Environmental Agency, 2007).
FIGURE 2.1Overview of the main contaminants affecting soil and ground water in Europe shown as percentage of contaminated sites.Data from European Environmental Agency (2007). (For colour version of this figure, the reader is referred to the online version of this book.)
FIGURE 2.2Overview of activities causing soil contamination in Europe shown as percentage of contaminated sites.Data from European Environmental Agency (2007). (For colour version of this figure, the reader is referred to the online version of this book.) Remediation Technologies
Contamination of the subsurface by persistent organic contaminants remains a significant problem, even after decades of research on remediation technologies (Watts et al., 1999; Watts and Teel, 2005). New types of remediation technologies and modifications of existing technologies are continuously developed by scientists and engineers. First approaches for remediation focused on excavation, pump and treat via activated carbon, bioremediation, and natural attenuation. In the 1990s the first reports on ISCO were published. An overview of the different types of remediation technologies divided into three major categories is presented in Figure 2.3. Only the technologies listed under ‘Degradation’ in Figure 2.3 will result in degradation of the hazardous contaminants and hence eliminate the toxicity and because of this, these technologies should be the ones preferred. In practice these treatment technologies are often complex to control and it is difficult to predict the outcome. Consequently, excavation and other low-tech methods are still by far the most frequently applied remediation technologies. Very often remediation consists of a combination of containment, removal and degradation technologies. No contaminated sites are identical with respect to the type of contaminant, geology, hydrogeology and geochemistry and, therefore, all the mentioned remediation technologies still play important roles. However, some contaminations are too complex to be remediated cost-effectively with the technologies available today, and therefore, further improvements of existing techniques and development of new techniques are still needed. An important task in the present Ph.D. work was to gain a better understanding of the processes occurring in situ in the contaminated soil and ground water. One of the newer technologies attracting a lot of interest and possessing a great potential is ISCO.
FIGURE 2.3Overview of remediation technologies divided into three major categories.(For colour version of this figure, the reader is referred to the online version of this book.) In situ Chemical Oxidation (ISCO)
ISCO is a technology involving the introduction of chemical oxidants into the subsurface in order to transform contaminants into less harmful compounds. Hydrogen peroxide was the first chemical oxidant investigated and used for full-scale treatment. Shortly after, ozone and permanganate came into use. In the past few years persulphate, percarbonate and other peroxygens have provided more options. The use of permanganate for ISCO is considered an almost fully developed technique, is relatively easy to apply compared to other oxidants and has been used at numerous sites with well-documented results. Hydrogen peroxide has also been deployed at a large number of sites. However, the use of this oxidant is much more complex because of the numerous reactive intermediates and mechanisms occurring in the subsurface, which makes the process difficult to control and predict in the field. Ozone has only been used in a much more limited number of applications. Persulphate has, during the past 5–10 years, been used in an increasing number of full-scale remediation projects (Krembs et al., 2010). Since no sites are identical,...