untitled HAL Id: hal-00560666 https://hal.archives-ouvertes.fr/hal-00560666 Submitted on 29 Jan 2011 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Dimensions of Environmental Engineering Birgitta Dresp To cite this version: Birgitta Dresp. Dimensions of Environmental Engineering. Open Environmental Engineering Journal, Bentham Open, 2008, 1, pp.1-8. �10.2174/1874829500801010001�. �hal-00560666� https://hal.archives-ouvertes.fr/hal-00560666 https://hal.archives-ouvertes.fr The Open Environmental Engineering Journal, 2008, 1, 1-8 1 1874-8295/08 2008 Bentham Open Open Access Dimensions of Environmental Engineering Birgitta Dresp-Langley* Department of Mechanical and Civil Engineering, LMGC, UMR 5508 CNRS, Montpellier, France Abstract: The impact of human activity on the biosphere has produced a global society context in which scarcity of natu- ral resources and risks to ecological health such as air pollution and water contamination call for new solutions that help sustain the development of human society and all life on earth. This review article begins by recalling the historical and philosophical context from which contemporary environmental engineering has arisen as a science and domain of techno- logical development. Examples that deal with some of the core issues and challenges currently faced by the field, such as problems of scale and complexity, are then discussed. It is emphasized that the sustainability of the built environment de- pends on innovative architecture and building designs for optimal use and recycling of resources. To evaluate problems related to global climate change, storms, floods, earthquakes, landslides and other environmental risks, the behaviour of the natural environment needs to be taken into account. Understanding the complex interactions between the built envi- ronment and the natural environment is essential in promoting the economic use of energy and waste reduction. Finally, the key role of environmental engineering within models of sustainable economic development is brought forward. INTRODUCTION Global society and the dominance of the human species over the biosphere have provoked a situation where ecologi- cal and environmental engineering are the inevitable profes- sional response to the most pressing problems of humankind. The goal of both theoretical and practical environmental en- gineering is to help society function. Combining theory, re- search, practice, and education defines the basis for ex- change of knowledge relative to engineering solutions that are socio-economically justifiable, responsible, and consis- tent with a sustainable development of communities, popula- tions, and nations. Such solutions aim at planning, designing, and improving structures, facilities, and infrastructures for a responsible, economic, and efficient use of energy resources. For the protection of the health of man and the environment, environmental engineering involves identifying and prevent- ing contaminant behaviours in man-made and natural sys- tems, and, above all, to minimize the negative impact, or ecological footprint, of humankind on all systems and cycles upon which life depends. This article proposes a brief review of the historic background facts, philosophical considera- tions, theoretical concepts, and pragmatic issues from which contemporary environmental engineering has arisen, as both a scientific discipline and a domain of applied research and development. HIS TO RICA L AND PH ILOS OPHICA L BAC K - GROUN D The Industrial Revolution marked a turning point in the history of humankind. Towards the end of the 1700s, manual labour-based economy was progressively replaced by indus- try and the manufacture of machinery. Large scale produc- tion of chemicals significantly contributed to the economic *Address correspondence to this author at the Department of Mechanical and Civil Engineering, LMGC, UMR 5508 CNRS, Montpellier, France; Tel: +33 (0)4 67 14 46 81; Fax: +33 (0)4 67 14 39 23; E-mail: dresp@lmgc.univ-montp2.fr development and concomitant pollution of the natural envi- ronment brought about by the Industrial Revolution, with the production of sulphuric acid, hydrochloric acid, and alkalis. Trade expansion was facilitated by the introduction of rail- way systems. Steam powered machinery engendered dra- matic increases in production capacity and the technological developments and engineering breakthroughs of the Indus- trial Revolution promoted urbanisation. The rapid growth in urban populations increased the demands for produce from outside the cities, and the ecological footprint of whole coun- tries soon reached beyond their borders, leading the way towards modern global economy [1]. Some philosophers reacted to the Industrial Revolution through writings that re- introduced and emphasized the profound relationship be- tween man and nature. Ralph Waldo Emerson’s book Nature is one such example [2]. The book is, in fact, a compelling essay in which Emerson defines nature as an all-encom- passing entity which is inherently known to us rather than being merely a component of the outside world. Emerson’s philosophy established, especially in the US, a way of look- ing at man and his natural environment which placed nature at the centre of humanity. Others, such as Henry David Tho- reau were influenced by Emerson’s writings. Emerson took a philosophical standpoint which marked a significant point in the history of science and, in particular, of the biological and contemporary neurosciences by advocating the idea that the natural world and the mental world, or workings of the hu- man brain, are bound to have common biological origins. Both Emerson’s and Thoreau’s writings contributed signifi- cantly to environmentalism as a philosophy and a political and social movement concerned with the conservation and improvement of the natural environment, both for its own sake and in regard to its importance to civilization and life in general. Later, Aldo Leopold’s book A Sand County Alma- nac [3] became a key reference which reinforced the ethical standpoint of environmentalist philosophy, arguing that it is unethical to harm the natural environment, and that human- kind has a moral duty to respect and protect it. The ethical 2 The Open Environmental Engineering Journal, 2008, Volume 1 Birgitta Dresp-Langley standpoint has significantly influenced the science of modern environmental engineering and economics [4, 5, 6]. While the engineering community showed little interest in envi- ronmental issues for a long time after the Industrial Revolu- tion, this situation changed with Richard Buckminster Fuller, a pioneering scholar and engineer who was one of the first of his kind to promote environmental issues as a core topic of both fundamental and applied science. His ideas and writings have contributed substantially to the development of the the- ory and practice of contemporary environmental engineering. ENGINEERING FOR ‘LIVINGRY’: RICHARD BUCKMINSTER FULLER’S PIONEERING VISION Richard Buckminster Fuller was born in 1895 in Massa- chusetts and, expelled from Harvard University as a student, subsequently became a prominent early environmental activ- ist and scholar, initiating and collaborating in innovative design projects with professionals, artists, and scientists worldwide. An engineer, architect, designer, developer, sci- entist and scholar, he registered a large number of US Pat- ents for his innovations. Buckminster Fuller lectured at lead- ing Universities all over the world and devoted his profes- sional practice and teachings to applying engineering and the principles of science to solve problems of society, aware that humankind would soon have to rely on renewable sources of energy. His anticipatory vision of a planet running dry of natural resources was confirmed by the Millennium Ecosys- tems Assessment (MEA) no later than two decades after his death in 1983, with the conclusion that human activity has over the last few decades altered ecosystems more rapidly and extensively and accelerated global climate change more noticeably than in any comparable time span in the history of man. Way ahead of his time, Richard Buckminster Fuller promoted a systemic approach to environmental issues. His work explored solutions for energy and material-efficient engineering and design such as • foldable emergency shelters • lightweight building structures • renewable resources and recycling • aerodynamic vehicles • wind energy solutions for large buildings and individual households • tap and shower systems that help reduce water consumption Fuller’s prototype of a curve-shaped, energy-efficient, low-cost, modular and transportable living structure de- signed in the 1940s, the ‘Dymaxion House’ (see Fig. 1 be- low), was equipped with innovative technology exploiting natural winds for cooling and ventilation and featuring indi- vidual taps and showers with economic spray systems to help reduce water consumption. In his book Critical Path [7], Buckminster Fuller reso- lutely and passionately advocates the idea of doing more with less. He argues for an efficient and economic use of natural resources, and promotes the search for solutions that sustain the development of all forms of life on Earth. He can be regarded as the father of engineering for sustainability, and his philosophy was definitely a forerunner of the modern anthropocentric approach [8] to the environmental sciences. His teachings and whole conception of education were fo- cussed on fostering the development of life-long skills cover- ing a broad range of knowledge and competence to achieve what he called an “omni-successful education”; his view of science was in essence an inter-disciplinary one. The concept of ‘livingry’, which Fuller invented as opposed to ‘weap- onry’, laid the theoretical foundations on which the modern concept of sustainable development is grounded. His integra- tive view of engineering science can be summarized by the schematic model shown in Fig. 2 below. Fig (2). Fuller’s world-view can be regarded as the first anthropo- centric vision of the natural and built environment, where man- made facilities and transport exploit and exhaust raw materials and natural energy resources such as air and water, which are essential per se (red arrow) for sustaining human and other life on Earth (“livingry”). Fuller predicted that natural resources would soon be jeopardized by over-exploitation and pollution. He is considered to be one of the first engineering scientists to have consistently and actively promoted renewable energy solutions and waste recycling. The impact of human engineered systems on the natural environment has become a global issue of the highest impor- tance since Fuller’s death in 1983. The grander goals of modern engineering have since been concerned with the remediation and prevention of environmental pollution and the exhaustion of raw materials and other natural resources. FROM ECOSYSTEM STUDIES TO ENVIRON- MENTAL ENGINEERING From the 1960s systems ecology blossomed as a disci- pline within the biological sciences. Ecosystem approaches contributed to increase knowledge on how the atmosphere Fig (1). Richard Buckminster Fuller’s prototype of energy efficient individual housing, the Dymaxion House, is displayed at the Henry Ford Museum in Dearborn, Michigan, US. Livingry Buildings Natural Resources Transportation Dimensions of Environmental Engineering The Open Environmental Engineering Journal, 2008, Volume 1 3 responds to the combined effects of global metabolism and geochemical recycling, and how these biogeochemical proc- esses are in turn influenced by changes in the atmosphere. The seminal books by Eugene Odum and Howard Odum [9, 10] provide a complete review of the history and fundamen- tals of systems ecology. Systemic approaches in ecology draw from a wide range of scientific disciplines including geology, biochemistry, conservation biology and evolution- ary ecology. Some authors [11] have attempted to subdivide the field of ecology into approaches concerned with biodi- versity and the conservation of ecological entities (“compo- sitionalism”) on the one hand, and more systemic ap- proaches aiming at understanding processes of ecosystem functioning (“functionalism”) on the other. The reality of current research in the field, however, shows that integrative forms of ecological research are emerging, blurring the lines between specialized domains within and beyond ecology. Theoretical models tend towards increasingly global bio- sphere approaches, aiming at an understanding of the Earth as a whole. In the model of a balanced global biosphere, photosynthesis fixes carbon dioxide and regenerates oxygen while humans, animals, plants and microbes draft from the atmosphere by using oxygen and by generating carbon diox- ide at an equivalent rate. In the real world, such balanced behaviour no longer exists. The major challenge for ecology now is to gain an understanding of large-scale effects caus- ing imbalanced behaviour in the global biosphere, and to further our knowledge about underlying biogeochemical processes and how they interact. Engineering science has acquired a critically important role within this endeavour. Solutions to the most pressing problems of an imbalanced Earth are expected to result from adequate engineering de- velopment and technology, based on the interpretation of research models and observational data. Theoreticians have previously insisted on differences between ecological engi- neering and environmental engineering [12], the former be- ing seen as essentially concerned with constraints on ecosys- tems and living organisms, while the latter would mainly address constraints on non-living environments and would therefore be more closely identified with “conventional” engineering [12, 13]. Such views fly in the face of the fact that engineering has evolved dramatically over recent years towards increasingly global and integrative approaches to society problems, in parallel with major advances in the fields of the fundamental life sciences, computer sciences, and design technologies. The idea of a theoretical separation between issues and topics of ecological engineering on the one hand and environmental engineering on the other is now difficult to reconcile with contemporary engineering, both in terms of research and practice. The necessity of replacing the entire domain of science within a context of urgency has produced a situation where “conventional engineering” is a thing of the past. With the introduction of the concept of sustainability in terms of a global challenge [14] hitting al- most any field of modern science and technology and there- fore reaching well beyond classic ecology, a significant shift in thinking has occurred. Global anthropocentric theories have begun to tighten existing links between scientific do- mains. These include links between mathematics, computer modelling, and economics [15], and links between the hu- manities and the social sciences to the benefit of environ- mental science [16]. SUSTAINABILITY: FROM LOCAL COMMUNITY TO GLOBAL SOCIETY While the practice of environmental engineering has evolved considerably during the past two decades, its under- lying contract with society has always been the same. Envi- ronmental engineering is about providing quality of life for all, with the protection, nurture and renewal of a fragile envi- ronment in mind. Environmental scientists predict that local communities and individual houses will generally become smaller, and will be based on principles of ecological design [17, 18], where the restoration of natural environments within urban landscapes is to play an important role. The ecological approach to the built environment involves a ho- listic design approach where energy use and resource deple- tion is reduced, and external and internal pollution causing potential damage to users and the environment is minimized. An example of such design at the level of individual housing is the Hockerton project, which was completed in Great Brit- ain in 1996 and listed in the catalogue of “best practice” ex- amples by the European Green Building Forum in 2001 [19]. In this project, rainwater from the roofs is filtered and col- lected as drinking water. Since plastic is likely to give off toxics, copper gutters are used. In order to save energy, water is heated with a pump. Water falling elsewhere on the estate is pumped to a reservoir large enough to hold several months' supply for washing laundry and growing crops. The reservoir’s capacity is 150 m , and the water runs trough a natural filter system. All sewage treatment systems are bio- logical and rely entirely on natural organisms [18]. A me- chanical aeration system recycles air and preserves heat within the building. Heating costs are minimized. Figure 3 shows how the houses in the Hockerton project were covered with earth to trap heat. Sustainable building design is the thoughtful integration of ecologically aware architecture and electrical, mechanical, and structural engineering. In addition to concerns for aesthetics, proportion, scale, texture and light, ecological long term costs are taken into account. Con- necting building design with nature brings new forms of life to urban dwellings, and reminds us of our place within na- ture. Sustainable building design is to take into consideration a wide range of cultures, races, religions and habits to meet the needs of individuals and communities, at local and global scales. Fig (3). In the Hockerton Project (UK, 1996) roofs were covered with soil rather than tiles to increase energy efficiency by trapping heat. The soil acts as a giant radiator. The field of environmental engineering is to face the challenge of an unprecedented global urbanization and in- 4 The Open Environmental Engineering Journal, 2008, Volume 1 Birgitta Dresp-Langley dustrialization in developing countries such as Africa, which seek to increase their wealth and living standards. Engineers nowadays have to be able to adapt their vision and respond to the needs of societies at a much larger and more complex scale, where cooperation with and within other cultures is required. Among the most urgent demands currently put to the profession, we may list the following: • educate the public to increase awareness of envi- ronmental issues • mitigate the threats of global climate change • provide adequate supplies of fresh water • deal with the pressures of increasing population • anticipate energy shortages, searching for renew- able energy sources • develop tools to assess the performance and sustainability of existing structures • design ecologically friendly transportation systems • estimate impacts and anticipate risks (earthquakes, floods, storms, contamination) • restore and reclaim mined and disturbed landscapes • develop and strengthen links with other fields of science such as mechanics, biochemical engineer- ing, the geological, biological, computer, social and management sciences These complex issues cut across all the engineering do- mains and require a scientific analysis at different levels of scale and complexity. Management training and expertise to put new solutions into practice is an essential aspect of mod- ern environmental engineering. (Fig. 4) proposes a schematic view of problems to be addressed, at small and large scales. ADAPTIVE PROJECT MANAGEMENT TO COPE WITH PROBLEMS OF SCALE AND COMPLEXITY A factor which is often difficult to assess in the search for sustainable solutions is that of the scale and complexity of a given problem. Engineers may be perfectly capable of work- ing out a basic physical design or the hydro-geomorphology for what may seem an appropriate solution to a problem of the environment, but may ultimately not provide a successful solution because the scale or complexity of the problem was not adequately predicted and analyzed. The complexity and scale of biological systems [20] make it difficult, sometimes impossible, to understand how these systems behave at dif- ferent levels of organization from elemental cycles to com- munity metabolisms, and how these levels interact. Moreo- ver, biological systems and components [21] take different and variable times to respond to engineering solutions or to changes in general. The timescale of their responses may exceed that of reasonable monitoring expectations and may render reliable predictions impossible. This timescale prob- lem can be illustrated by the example of damaged coastal reefs, where times for a full functional restoration at a site may be estimated in terms of centuries. Also, biological sys- tems respond to changes as they develop, and this natural adaptation may make it difficult or impossible to work out ready regulatory recipes. A different but related problem of scale in environmental engineering is that related to the number of people concerned or affected by a project. Adap- tive project management was proposed as an approach that helps cope with problems of scale [22, 23]. Adaptive man- agement allows for changing goals as an engineering project evolves with time. Intelligent monitoring combined with general project goals allow realistic re-evaluations of what can be accomplished. Adaptive management works best with a conceptual model that leads to clearly defined, explicit general goals [23]. The success criteria in adaptive project management vary from case to case, and the more success criteria depend on process and function per se, the more it is likely that general goals will be reached. For processes that are well understood, a list of detailed success criteria can be established from the outset. Most importantly, adaptive man- agement permits the learning process inherent to modern engineering research and practice to be progressively inte- grated into a given project. As far as planning is concerned, any well-developed project plan should include a flow chart with branches at points in the process where uncertainty ex- ists, and where deviation from an expected outcome pathway leads to an anticipated alternative endpoint. Well-designed engineering projects incorporate uncertainty into the process, and at the outset inform the public or responsible party of potential problems, alternative solutions, and their cost. Fig (4). The built environment reflects the material wealth of cities and nations. Its sustainability largely depends on the care and rigor with which resource use and re-use, emissions, structural resistance to earthquake threats, land-fill volumes and other environmental factors are taken into account, from the planning, design, construc- tion and anticipated life cycles to the demolition and re-use of buildings. Understanding interactions between the built environ- ment and its natural context is essential for promoting an economic use of resources. Finding sustainable solutions involves research for renewable resources and the analysis and management of risks such as global climate change, earthquakes, floods or storms. The avail- ability and consumption of energy influences both the nature and extent of pollution and the extent to which polluted atmosphere or polluted sites can be regenerated or restored (intersection between orange and grey circles). Countries with poorly developed infra- structures in which energy supply is scarce will have to cope with environmental problems at a different scale compared with coun- tries which have highly developed infrastructures and extensive energy production and consumption. risk analysis and management renewable resources sustainable construction restoration water use & re-use ECO-PARKS BUILT ENVIRONMENT & LANDSCAPE Structures Performance Life-Cycles ATMOSPHERE & ENERGY Air Quality Climate Change WATER Water Resources Water Quality Dimensions of Environmental Engineering The Open Environmental Engineering Journal, 2008, Volume 1 5 These are represented by alternative pathways and endpoints in the project flow chart. Adaptive management allows all parties involved to consider a variety of potential end- products and determine if they are acceptable. Marcus [24] discussed the example of a project for tidal marsh restoration in San Francisco Bay, which affected a large number of user groups in the area and required continual reworking of the engineering plans to satisfy the political and economic con- cerns expressed by these groups and the general public. Evaluating the impact of man-made damage or natural disas- ters on the environment and public concerned is another im- portant, scale-dependent issue within the science and prac- tice of environmental engineering. IMPACT STUDIES: ASSESSING DAMAGE AND LOSS OF RESOURCES Landscape planning and policy making are affected by the impact of both man-made and naturally caused damage to the environment. As an example, we may consider the case of earthquakes, such as that which occurred in Septem- ber 1999 in Central Taiwan, inducing several large-scale landslides and causing environmental and resource problems which required a functional analytical ecosystem approach to the problem beyond the standard technological solutions. The impact study by Lin, Lin, & Chou [25] gives an example of a long-term investigation into the consequences of earth- quakes on the environment. In this study, changes of the post-quake landslides, vegetation recovery conditions, and soil loss were assessed using imaging technology such as multi-temporal SPOT satellite images, and analytical image transformation. Mathematical models for vegetation recov- ery analysis based on calculations of normalized difference vegetation index (NDVI) and Universal Soil Loss Equations [26] guided the research and evaluation. Landslides were identified on the basis of pre- and post-quake air images us- ing image differencing algorithms and change detection thresholds. Vegetation recovery rates (VRR) were computed to quantify successive conditions of vegetation recovery at landslides. To estimate the environmental impact of the de- nudation sites, soil loss before and after the earthquake was calculated on the basis of geomorphology analysis. The re- search revealed large-scale impacts of the earthquake and the concomitant landslides, and enabled further decision making policies and planning in the affected areas. After six years of monitoring, vegetation recovery was found to have reached 89.69%, which gives an overall assessment of nature’s abil- ity to regenerate vegetation after large-scale landslides. However, other risk factors such as typhoons could abolish such renewal in a short time. To mitigate such risks, engi- neering solutions for geo-morphologically unstable sites need to be developed. Other medium and large-scale risks that challenge the expertise of researchers and practitioners in the field of environmental engineering are those repre- sented by the contamination of water supplies through toxic trace elements. RISK EVALUATION AT MULTIPLE LEVELS OF ORGANIZATION Inadequate water supply and related health hazards are a daily problem faced by millions of people worldwide. The management of the water environment for sustainable human benefit requires environmental policies that promote eco- logical health, meaning both ecosystem health and human safety. The concerns of environmental engineers for water supplies, the mitigation of contamination, and the promotion of ecological health nowadays extend beyond the perform- ance and safety of individual components. Entire water sup- ply systems and their interactions with other systems are taken into account, which involves evaluating the risks and analyzing the consequences of water contamination by pathogens or toxic trace elements. These may originate from various sources. Metal traces in soils, for example, were found to cause potentially contaminant effects at all levels of biological organization, from cellular to ecosystem levels, even in sites where the corresponding surface water met wa- ter quality criteria [27]. The presence of COPECs, or con- taminants of potential environmental concern [28] in soil and water represents an ecological risk at the ecosystem, com- munity, population, individual, cellular, and molecular lev- els. While the detection and identification of COPECs as such is, in principle, not difficult, the current problem with toxicity risk evaluation is that the specificity of contaminant effects, and the insight gained into the mechanisms of toxic- ity as such, is lesser the higher the level of organization [29]. Indicators of toxicity such as morphological changes at the tissue level, ultra-structural changes at the cellular level re- vealed through electron microscopy, and biochemical changes at the molecular level permit establishing and to quantifying cause-effect relationships. Evaluation of con- tamination risks at the level of ecologically relevant proc- esses is far more difficult and susceptible to biases due to the lack of individual data on exposure, outcomes, or confound- ing variables that may contribute to a measured effect [30]. At lower levels of organization, critical changes occur more rapidly and may provide early warnings of toxicological ef- fects on populations [29, 30]. However, despite the greater mechanistic understanding and specificity of effects at lower levels of organization, the insight provided may be limited because the significance of these effects at the ecological level or the amplitude of their bio-magnification is unknown. The usefulness of indicators thus depends on the cross ex- amination of multiple levels of organization. Effects of trace- elements on plant communities, for example, may be rele- vant because the production of plant matter is a primary source of organic carbon for aquatic ecosystems. A possible food-chain transfer from contaminated soils should also be considered. Changes at the ecosystem level may be inferred when contaminants exceed benchmark levels that are toxic to soil bacteria, suggesting that their functional properties re- lated to nutrient cycling and energy flow have been affected [27]. The pathways for the migration of contaminants away from a given source may involve transport in surface water and shallow groundwater. Although dissolved metal trace elements in water may seem harmless with respect to toxic- ity, this does not alleviate concerns over oral uptake of trace elements through contaminated food. It is generally believed that the uptake of adsorbed trace elements is significantly less dangerous than the absorption of dissolved forms [31]. However, the relative importance of the different routes of exposure remains unclear and at high concentrations the bioavailability of even a small fraction of adsorbed trace elements from diet could be important, which would support the hypothesis that diet is a significant route of exposure [32, 33]. At the level of human populations, the risk of mortality 6 The Open Environmental Engineering Journal, 2008, Volume 1 Birgitta Dresp-Langley from cancer is estimated to be increased in people exposed to certain trace elements through diet, even at seemingly low concentrations [34]. Eco-toxicology has, for the last 30 years, been concerned with studying the effects of contami- nants on the biological integrity and ecological health of communities and ecosystems. Newman and Unger [35] give a complete and comprehensive overview, from the general principles of eco-toxicology to examples of scientific in- depth studies. Some of these are concerned with the effects of environmental pollutants at different levels of biological organization, from the molecule to the biosphere as a whole. How biotic integrity can be assessed at different levels, and used as a monitoring tool to guide further investigation, is discussed. To restore the ecological health of water, soils, and sediments, ecological and environmental engineering design solutions are applied to an increasingly diverse range of innovative projects for the effective management of natu- ral resources. Adequate technologies have been created and are currently used within the fields of environmental protec- tion and restoration, the food sector, industrial waste and sewage treatment, and architecture and landscape design. These technological solutions are the core of turn-key strate- gies aimed at reducing the negative impact of humankind on natural resources. TURN-KEY STRATEGIES TO RESTORE ECOLOGI- CAL HEALTH Environmental engineering practice is all about what Ar- onson et al [8] called “the search for effective turnkey strate- gies to mitigate or overturn the negative environmental ef- fects of the 20 th century’s growth path”. A turnkey strategy, in business language, is a strategy or solution where the pro- vider or designer (research and development) undertakes the entire responsibility from design to completion and commis- sioning. The client (society) only has to turn the proverbial key to make the solution function as it should. Several con- crete examples of environmental turn-key solutions at the medium scale are given in the case examples presented by Todd, Brown, & Wells [18]. Their applied functionalist ap- proach shows how engineered ecosystem designs and con- cepts can be readily applied to solve concrete environmental problems such as • sewage treatment through biologically diverse, vas- cular and woody plants, which are particularly suit- able for waste treatment • restoration of contaminated water by floating de- vices using wind and solar energy • organic industrial waste treatment • ecologically designed systems for air purification, humidity control, water re-use, waste treatment and food production within architectural structures • the integration of industrial and agricultural activity sectors in urban design and landscape planning through the creation of eco-parks The economic viability of integrative ecosystems and en- vironmental engineering design within urban settings is a topic that concerns both the general public [36] and local authorities involved in planning and decision making. Urban environments provide the basis for most of the world’s eco- nomic activities, including tourism and the leisure industry. Urban planning and development has a major impact on the economic performance of companies, corporations and na- tions, affecting human activities at all levels. Demographic estimates of a large number of additional inhabitants of the planet for the next decade require planning and development of basic housing and infrastructures, which is to incur a gi- gantic cost to support the predicted population growth. At the same time, infrastructures are rapidly decaying in many countries and are urgently in need of repair and maintenance, which represents projects associated with another enormous outlay. The increasing trans-national embedding of global sustainability issues will lead to private-public partnerships and projects that will be delicate to manage, especially in developing countries that do not have a tradition of private ownership and public infrastructure. Thus, both scientists and professionals in the field of environmental engineering will be confronted with unprecedented social and economical challenges. ENVIRONMENTAL ENGINEERING AND SUSTAIN- ABLE ECONOMIC DEVELOPMENT Whether an innovative design solution that benefits the environment and the people who live in it will ultimately meet success depends on economical and social factors. Questions of cost-effectiveness or whether people are likely to accept and live with a solution proposed to them need to be addressed. Idealistic visions have to lead to realistic out- comes and ethical concerns are to be taken into account in the light of economical and political pressure. This involves cost-benefit analyses, feasibility studies and awareness of the political climate and decision making context as potential limiting factors to a project. The emerging discipline of eco- logical economics addresses such complex problems at the interface of the economic system and the global ecosystem that sustains and contains it. Like environmental engineer- ing, ecological economics espouses a systems approach that aims to offer solutions to the problems of society in the 21st century. Economics is generally defined as the science of allocation of scarce resources among alternative desirable ends. This implies a specific sequence of steps in economic analysis and, finally, the economist must decide what ends are to be pursued. Many argue that decisions on ends should be left to democratic processes, suggesting that an essential precursor to economic analysis is the democratic process that successfully articulates the desired goals. Once these latter have been identified, the economist can analyze what re- sources are necessary to achieve them, and which of these resources are the scarcest. The final step is allocation, via whatever institution or mechanism is most appropriate for the resources and ends considered [17]. In classical econom- ics, there is no absolute resource scarcity. As a resource be- comes scarce, its price increases, which provides market incentives to develop substitutes. The problem with such reasoning is that the human and all other species rely for their survival and welfare on hitherto non-marketed ecosys- tem services such as climate, air, water, and a clean atmos- phere. Though increasingly scarce, most of these services have no price and therefore do not generate any feedback from markets to indicate their scarcity. Theoretical econom- ics concentrates on growth and on markets, but markets fail to efficiently allocate most natural resources [37], possibly Dimensions of Environmental Engineering The Open Environmental Engineering Journal, 2008, Volume 1 7 with the exception of water, given that there is now water pricing in many areas, at least for urban and industrial use. The critical problem is that, as an economy grows, it does not expand into a void, but into a finite sustaining and con- taining biosphere. Throughout the process of economic growth, society exhausts natural capital, and thereby its vital support functions. The potential irreversibility of this process has sometimes been discussed on the example of energy consumption and the second law of thermodynamics [38]. This universal law of increasing entropy or increasing un- availability of energy in a physical system predicts that in any isolated system entropy increases. Applied to the eco- nomic process, as discussed by Georgescu-Roegen [38], the second law of thermodynamics leads to predict that, ulti- mately, the scarcest energy resource will be low-entropy matter-energy. The ability of societies to rely on such energy would thus, ultimately, be limited. On the other hand, there is an anticipated abundance of a variety of renewable, non- polluting forms of energy [17], and the development of in- novative engineering solutions that are radically different from current designs will play an important role in environ- mental engineering as the 21 st century progresses. The search for society forms capable of allocating resources in a sus- tainable and effective way has become a topic of major con- cern world-wide. Economists [15, 39, 40] now question the classic economic growth models, which postulate a quantita- tive increase in the rate at which an economy transforms natural resources into economic output and waste. New theo- ries of economic development, which incorporate concepts of a development ethic [6] and “dematerialization”, have been proposed, such as Robert Ayres' theory [40], which insists on the difference between “more” and “better”, and which challenges the classic growth paradigm by pointing out that the relevant measure of economic output is not the quantity of goods produced, but the quality and the, not nec- essarily material, value of final services provided to the con- sumer. Such worldviews tend to separate the economic proc- ess from energy and material issues, and place priorities on increasing the quality of human life and well-being while limiting resource use and waste production. The re- investment of capital produced by global economy into envi- ronmental engineering research and the development of in- novative technology and solutions will become an important strategy to such an end. Figure 5 here below illustrates these implications. CONCLUSIONS Contemporary environmental engineering is about devel- oping systems, structures, methods, tools and infrastructures that help protect human health and the environment, includ- ing sustainable transportation and energy systems, and solu- tions for safe and adequate water supply worldwide. Prob- lems have to be analyzed on a large scale, taking into ac- count the growing trans-national embedding of environ- mental research and technology. The examples discussed here illustrate how the theory, research and practice of envi- ronmental engineering, in contact with other disciplines such as ecology, geology, biology and economics, address the most urgent problems currently faced by global society. 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