Materials cycle

Cycle. A system consisting of two or more connected reservoirs, where a large part of the material is transferred through the system in a cyclic fashion. If all material cycles within the system, the system is closed. Many systems of connected reservoirs are not cyclic, but instead material flows unidirectionally. In such systems some reservoirs (at the end of the chain) may be accumulative, whereas others remain balanced (nonaccumulative) cf. Holland (1978). 

Conversion process - a chain of process in a cycle (e.g. carbon cycle or other material cycles). 

Microbiologically influenced corrosion is defined by the National Association of Corrosion Engineers as any form of corrosion that is influenced by the presence and/or activities of microorganisms. Although MIC appears to many humans to be a new phenomenon, it is not new to the microbes themselves. Microbial transformation of metals in their elemental and various mineral forms has been an essential part of material cycling on earth for billions of years. Some forms of metals such as reduced iron and manganese serve as energy sources for microbes, while oxidized forms of some metals can substitute for... 

Figure 7.3 Simplified diagram of the total material cycle.

Idris, A., Hassan, M.N., and Chong, T.L., Overview of Municipal Solid Wastes Landfill Sites in Malaysia, Proceeding of 2nd Workshop on Material Cycles and Waste Management in Asia, NIES Tsukuba, Japan, December 2-3, 2003. 

Ayres, R.U. Ayres, L.W. Industrial Ecology Towards Closing the Materials Cycle, Edward Elgar Publishing Cheltenham, UK, 1996. 

Ecke, H., Menad, N. Lagerkvist, A. 2002. Treatment-oriented characterization of dry scrubber residue from municipal solid waste incineration. Journal of Material Cycles Waste Management, 4, 117-126. 

The Chemical Leasing (ChL) approach is a new and innovative instrument to promote sustainable management of chemicals and close the material cycles between suppliers and users of chemicals ("closing the loops"). Chemical Leasing is applicable to large companies as well as small and medium size enterprises of different sectors. Experience shows that these new models reduce ineffective use and over-consumption of chemicals and help companies to enhance their economic performance. 

Figure 13.4b emphasizes the finite nature and strong irreversibility of an economic system. The stock of energy and resources will eventually run out and so will the absorptive capacity of the environment for waste. An obvious extension of Figure 13.4b, therefore, is the one represented by Figure 13.4c. Just like in nature, waste has to be recycled. In nature, there is no real waste. Every form of waste is a resource for a living system. This living system is very small and called a microbe. Microbes make sure that all matter recycles in nature. Man needs to assume this humble but valuable and important role of microbes in the economic system and make sure that the material cycles get closed. Therefore, energy (or rather work) is required. But obviously this work should not be supplied from a nonrenewable source, like fossil fuels, but rather from a renewable source like the sun. Figure 13.4c therefore seems to be characteristic for a sustainable economic system and agrees remarkably with the definition of sustainability from biological systems A...

It is clear that ultimately our only limitation to sustainable production is obtaining the exergy to run the production processes and to drive closed material cycles. In view of this, exergy can be considered the ultimate scarce resource in our technological processes, and exergy flows to or from these... 

A more complete thermodynamic analysis of processes deals not only with the efficiency but also with the extent to which renewable resources have been used and to which extent material cycles have been closed. 

It is natural to wonder why the combustion of biomass is an example of sustainable technology, as combustion releases COz in the atmosphere and therefore does not seem to close the material cycles. While the combustion does release COz into the atmosphere, the growth of biomass consume C02 (see Figure 16.2). Therefore, the final result is that there is no net release or consumption of COz if the biomass is replenished. For example, consider that a certain unit of active biomass absorbs one unit of C02 per unit time while growing. If one unit of this biomass is combusted, thus releasing one unit of C02, the result is that there is no net increase or decrease in COz emission. 

In this chapter, we will focus on solar energy and its conversion to other forms of energy. Solar energy is renewable and as an immaterial source, radiation, its emission is equally immaterial. In nature, it induces closed material cycles with overall outputs that closely resemble those of industry mechanical, chemical, and electrical energy, and chemical products. These properties (i.e., renewability, no emissions, and closed material cycles) make solar energy an excellent candidate for energy supply to a sustainable society in the making. 

Numerous case studies, examples, and problems illustrate the thermodynamic analysis of process performance to explain how to effectively analyze and optimize work flows and environmental resources. The authors compare the present industrial society with an emerging one in which mass production and consumption are in harmony with the natural environment through closure of material cycles. In this second edition, the book s structure of Basics, Thermodynamic Analysis of Processes, Case Studies, and Sustainability has been unaffected, but a few additions have been made. 

Biomarker molecule molecules that are indicative of source materials as well as processes of material cycling. 

The flux of energy through the system is accompanied by cycles of nutrients and other elements. Like every ecosystem, lakes and their surroundings and oceans include a biological community (primary producers, various trophic levels of decomposers, and consumers) in which the flow of energy is reflected in the trophic structure and in material cycles. 

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