Bioremediation and Sustainability

Research and Applications

Romeela Mohee, Ackmez Mudhoo

• Publisher: Wiley-Scrivener
• Year: 2012
• Print ISBN: 9781118062845
• eBook ISBN: 9781118371251
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Bioremediation and Sustainability is an up-to-date and comprehensive treatment of research and applications for some of the most important low-cost, "green, " emerging technologies in chemical and environmental engineering

Sustainable development requires the development and promotion of environmental management and a constant search for green technologies to treat a wide range of aquatic and terrestrial habitats contaminated by increasing anthropogenic activities with the main sources of contaminants being the chemical industries. Bioremediation is a technique that uses living organisms in order to degrade or transform contaminants into their less toxic forms. It is based on the existence of microorganisms with the capacity to attack the compounds on the enzymatic level.

Bioremediation is an increasingly popular low-cost alternative to conventional methods for treating wastes and contaminated media with the possibility to degrade these contaminants using natural microbial activity mediated by different consortia of microbes. Over the last few years, the scientific literature has revealed the progressive emergence of various bioremediation techniques. Bioremediation and Sustainability presents an up-to-date and comprehensive collection of chapters prepared in bioremediation technology research and applications.

The strategies covered in this volume can be applied in situ or ex situ, depending on the site in which they will be applied. In situ is the treatment done in the site of the contamination, and ex situ involves the removal of soil or water to subsequent treatment. There is a wide variety of techniques that have been developed in the past and are covered in this volume, such as natural attenuation, bioaugmentation, biostimulation, biosorption, composting, phytoremediation, rhizoremediation, and bioleaching.

Chapter 1

Elements of Sustainability and Bioremediation

Ackmez Mudhoo^* and Romeela Mohee

Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Mauritius, Réduit, Mauritius

^* Corresponding Author ([email protected])

Abstract

Bioremediation is becoming an increasingly popular and sustainable alternative to conventional methods for treating wastes and contaminated media in view to degrade and ultimately stabilize the contaminants using microbial activity. Many studies on bioremediation have been reported and the scientific literature has been accordingly enriched with an emergence of various bioremediation techniques. In this introductory chapter, the essential features of sustainability and the various in situ and ex situ bioremediation techniques have been outlined. This chapter also provides groundwork for the subsequent chapters which give a more detailed account of the anaerobic digestion technology, phytoremediation, vermicomposting and biosorption in their applicability and effectiveness for the biological treatment, stabilization and eventually remediation of contaminated environments.

Keywords: Sustainability, Biotechnology, Environmental contaminants, Bioremediation techniques

The Sustainability, Remediation and Biotechnology Link

Most segments of industrialized society are rethinking how behavior, reliance on technology, and consumption of energy impact the environment. Society is looking for ways to minimize these impacts, or avoid them altogether, so that human activity can become more sustainable. In point of fact, sustainability is a concept that coincides with many of the principles of Green Chemistry. Green chemistry, in first instance, is an essential part of green engineering. The definitions of green chemistry and green engineering share many commonalities, and the application of both chemistry and engineering principles is needed to advance the goals of environmental sustainability [1]. A working definition of green engineering proposed by Kirchhoff [1] is the design, commercialization, and use of processes and products that are feasible and economical while minimizing pollution at the source and risk to human health and the environment. The link between green chemistry and green engineering is strong in ensuring that inputs and outputs, both for materials and energy flows and budgeting, are as inherently safe as possible. Whilst Green Chemistry focuses on the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, it also lays down the ground plan for the design of the green engineering technologies needed to implement sustainable products, processes, and systems [1].

Features and Concepts in Sustainability

At a conference related to the environment in Rio in 2002, it is impossible to forget that 10 years earlier in June 1992 Rio hosted one of the most important international summits of the modern era, The Rio Earth Summit. Boutros Boutrous–Ghali the then United Nations Secretary–General in his opening address to the United Nations General Assembly in September 1992 commented that ‘The Earth Summit held in Rio in June marked an important milestone in awakening the world to the need for a development process that does not jeopardise future generations’. The 1992 Rio Conference achieved consensus in three important areas, namely,

i. it secured a set of agreements between governments which marked a significant advance in international cooperation on development and environment issues;

ii. it marshalled political commitment to these arrangements at the highest level and placed the issue of sustainable development at the heart of the international agenda, and

iii. it opened new paths for communication and cooperation between official and non–official organisations working towards developmental and environmental goals.

The developments leading up to the Rio Summit and which have flowed from it have made sustainability a serious issue for all developed societies and all sectors of business. The remediation of contaminated land offers a chance to demonstrate the concepts of sustainability but it must be recognised that we are still struggling to balance the many components of sustainability, despite for example, Agenda 21, Chapter 8(D) which was entitled ‘Establishing systems for integrated environmental and economic accounting’. Much has been done in this area but the systems are still complex and the concepts in need of further development. On the other hand, the Bruntland statement on sustainability is perhaps the most often cited definition of sustainability: Humanity has the ability to make development sustainable – to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs. Sustainability is not a panacea but a tool, under development, which still requires much honing. The main components of sustainability are typically expressed in terms of three main criteria which can be widened into many sub–criteria. These are:

• Technical/Environmental: Human health, Ecology, Resources, Climate
• Economic: Macro and Micro
• Social: Political and Legal

Sustainability and Scale of Environmental Pollution Clean–up

It is perhaps the accepted wisdom that contaminated land and waters are not a big enough issue to require detailed assessment as to sustainability. The common assumption is that on a national scale clean–up is a sustainable industry. The technologies for remediation of contaminated land and waters are beneficial as they reduce the risk from contamination and are unlikely to do much other harm. A little ponder on this issue shows that this is manifestly wrong since in many a way, little normalisation of the life cycle impacts of contaminated land and waters remediation has been carried out, even for simple situations such as dig and dump.

In this chapter, sustainable remediation is broadly defined as a remedy or combination of remedies whose net benefit on human health and the environment is maximized through the careful use of limited resources. To accomplish this, it becomes an instinctive need to embrace sustainable approaches to remediation that provide a net benefit to the environment. To the extent possible, approaches consist in minimizing or eliminating energy consumption or the consumption of other natural resources; reducing or eliminating releases to the environment, especially to the air; harnessing or mimicing a natural process; reusing or recycling of land or otherwise undesirable materials; and / or encouraging the use of remedial technologies that permanently destroy contaminants. It is also important to portray sustainable remediation practices not only as those practices that reduce global impacts (e.g., greenhouse gases), but also as those that reduce local atmospheric effects, potential impacts on worker and community safety, and / or the consumption of natural energy resources that might be attributable to remediation activities.

Conventionally, the selection of a remediation technology is based on factors such as the effectiveness of the remedy, implementability, cost considerations, and time constraints. Protection of the public via interception of contaminants, reduction of source(s), and mitigation of exposure pathways are prerequisites of remedy selection. Although these considerations are critical components in a traditional evaluation of remediation options, they do not evaluate and balance fully the external environmental, social, and economic impacts of a project. In other terms, the conventional approach generally focuses on the “internalities” of a remediation project and gives very little attention to its “externalities” where internalities lump the remedial objectives, system performance, environmental impacts local to the remediation site such as waste generation, water discharge, and air emissions (generally required by permit) and the externalities encompass the environmental impacts at the community, regional, and global levels.

Biotechnology and Bioremediation

Among the major new technologies that have appeared since the 1960s, biotechnology has attracted a great deal of attention and interest. Biotechnology has proved capable of generating enormous wealth and influencing every significant sector of the economy. Biotechnology has already substantially affected healthcare; production and processing of food; agriculture and forestry; environmental protection; and production of materials and chemicals [2]. The treatment of municipal wastewater by activated sludge method was perhaps the first major use of biotechnology in bioremediation applications. Activated sludge treatment remains a workhorse technology for controlling pollution of aquatic environment. Similarly, aerobic stabilization of solid organic waste through composting has a long history of use. Both these technologies have undergone considerable improvement [3].

The application of microbial metabolic potential (bioremediation) is accepted as an environmentally benign and economical measure for decontamination of polluted environments. Bioremediation methods are generally categorized into ex situ and in situ bioremediation. Although in situ bioremediation methods have been in use for two to three decades, they have not yet yielded the expected results. Their limited success has been attributed to reduced ecological sustainability under environmental conditions. An important determinant of sustainability of in situ bioremediation is pollutant bioavailability. Microbial chemotaxis is then postulated to improve pollutant bioavailability significantly; consequently, the application of chemotactic microorganisms can considerably enhance the performance of in situ degradation [2]. Therefore, in view of improving the potentialities of bioremediation, microorganisms have been isolated, selected, mutated and genetically engineered for effective bioremediation capabilities including the ability to degrade recalcitrant pollutants, achieve enhanced rates of degradation of target compounds, and assure better survival and colonization in target polluted niches [3]. More recently, enzymes have been successfully used in diverse bioremediation applications. Effective and controlled bioremoval of nitrate and phosphate contamination from wastewater has become possible. Hence, biotechnology is already playing a major role in maintaining a clean environment and this role will expand substantially as new bioremediation methods are developed and deployed for bioremediation of all kinds of industrial effluents and contaminated media.

Environmental Pollution and Biotreatment Variants

The problems of environment can be classified into the following subheads as most of the problems can be traced to one or more of the following either directly or indirectly: Waste generation (sewage, wastewater, kitchen waste, industrial waste, effluents, agricultural waste, food waste) and use of chemicals for various purposes in the form of insecticides, pesticides, chemical fertilizers, toxic products and by–products from chemical industries). Waste generation is a side effect of consumption and production activities and tends to increase with economic advance. The more serious concern is the increased presence of toxic chemicals such as halogen aliphatics, aromatics, polychlorinated biphenyls and other organic and inorganic pollutants which may reach air, water or soil and affect the environment in several ways, ultimately threatening the self–regulating capacity of the biosphere [4]. They may be present in high levels at the points of discharge or may remain low but can be highly toxic for the receiving bodies. The underground water sources are increasingly becoming contaminated. Zhang et al. [5] have recently detected legacy pollutants, polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane and its metabolites (DDTs), and some emerging organhalogen pollutants, such as polybrominated diphenyl ethers (PBDEs), hexabromobenzene (HBB), pentabromotoluene (PBT), 2,3,4,5,6–pentabromoethyl benzene (PBEB), 1,2–bis (2,4,6–tribromophenoxy) ethane (BTBPE), and dechlorane plus (DP) in an aquatic food chain (invertebrates and fish) from an E–waste recycling region in South China. Polychlorinated biphenyls, DDTs, PBDEs, and HBB were detected in more than 90% of the samples, with respective concentrations ranging from not detected (ND)–32,000 ng/g lipid weight, ND–850 ng/g lipid weight, 8 to 1,300 ng/g lipid weight, and 0.28 to 240 ng/g lipid weight. Pentabromotoluene, PBEB, BTBPE, and DP were also quantifiable in collected samples with a concentration range of ND–40 ng/g lipid weight.

There are three main approaches in dealing with contaminated sites: Identification of the problem, assessment of the nature and degree of the hazard, and the best choice of remedial action. The need to remediate these sites has led to the development of new technologies that emphasize the detoxification and destruction of the contaminants [6,7] rather than the conventional approach of disposal. Wang and Chen [8] recently developed a novel system of phytoremediation ex planta based on the overexpression of a secretory laccase [9] that catalyzes the oxidation of various aromatic compounds, including 2,4,6–trichlorophenol. All the more, rapid developments in understanding activated sludge processes and wastewater remediation warrant exploitation of different strategies for studying their degradation and some of the biological remediation terminologies such as bioleaching, biosorption, bioaugmentation, biostimulation, biopulping, biodeterioration, biobleaching, bioaccumulation, biotransformation and bioattenuation are being actively researched on [10]. Enzyme technology has equally been receiving increased attention.

Main Features of Bioremediation

Bioremediation is a fast growing and promising set of remediation techniques increasingly being studied and applied in practical use for pollutant clean–up. Vidali [11] has proposed the following classification of microorganisms involved in bioremediation processes: Aerobic microbes which bring about biodegradation in the presence of oxygen with Pseudomon...

Table of contents

• Cover
• Half Title page
• Title page
• Copyright page
• Dedication
• Preface
• Acknowledgments
• List of Contributors
• Chapter 1: Elements of Sustainability and Bioremediation
• Chapter 2: Natural Attenuation
• Chapter 3: Anaerobic Digestion Processes
• Chapter 4: Biosurfactants: Synthesis, Properties and Applications in Environmental Bioremediation
• Chapter 5: Phytoremediation: An Efficient Approach for Bioremediation of Organic and Metallic Ions Pollutants
• Chapter 6: Bioleaching
• Chapter 7: Biosorption of Heavy Metals – New Perspectives
• Chapter 8: Biofiltration: Essentials, Research and Applications
• Chapter 9: Modeling and Implementation of Sustainable Remediation Based on Bioventing
• Chapter 10: Bioremediation of Xenobiotics
• Index