Environmental burden

The key element of life-cycle design is Life-Cycle Assessment (LCA). LCA is generally envisioned as a process to evaluate the environmental burdens associated with the cradle-to-grave life cycle of a produc t, process, or ac tivity. A produc t s life cycle can be roughly described in terms of the following stages ... 

Finally, some authors have computed metal loading to the enviroranent from specific human activities, such as discharges of waste-water, and compared these with natural release rates. While the details of the computations and conclusions vary, the general observation for many metals is that anthropogenic contributions to metal ion transport rates and environmental burdens are approaching and in many cases have already exceeded natural contributions. A few such comparisons are provided in Tables 15-1-15-4. 

Synthesis of TGDD in sunlight could not be expected to add appreciably to this environmental burden. The formation rate from chlorophenols is strongly concentration-dependent, and its mechanism requires... 

During the life cycle assessment, the study authors are very often confronted with the fact that the product system has at its end more than one output. In these cases, we use the allocation. Allocation means the assignment of the share of total environmental burden to particular outputs [32]. The Standard recommends to avoid the allocation whenever possible, e.g. by extending systems or sub-division processes [36]. 

Williams AG, Audsley E, Sandars DL. Determining the Environmental Burdens and Resource Use in the Production of Agricultural and Elorticultural Commodities. Cranfield Cranfield University 2006. 97p. 

Fig. 2.19 Total environmental burden [kg/m2] in December of the 10th year of the simulation.

Fig. 2.21 Compartmental burden [t] (left panel), solid lines model experiment with aggregation of marine snow (AGG), dashed lines experiment with satellite assimilation (SAT). Migration of the centre of gravity of the total environmental burden (right panel). Dashed lines show the location of the COG at the end of the simulation. The COG of the SAT experiment is shown in blue, the COG of the AGG experiment in red. Circles represent monthly mean COGs.

Fig. 3.4 Year in which the maximal DDT burden is reached, left environmental burden, right ocean burden.

There are some ways to evaluate environmental burden in chemical synthetic processes. The atom economy is the fraction of the atoms in the product to the fraction of all atoms in the reactants. The E factor is the ratio of the mass of all waste to the mass of product. For the following reaction concerning the production of propylene oxide, calculate the theoretical atom economy and E factor. 

The above solution procedure has been applied to find replacement solvents for the following solvents Ethyl Glycol Acetate, Ethyl Glycol and Methylene Chloride. These three solvents are extensively used in the paints and ink industry, although, recent studies have shown that they carry an appreciable environmental burden in addition to being found harmful for the health of the people exposed to them (for example, employees in the manufacturing plants and/or consumers). 

The environmental burden of waterways with polychlorinated dibenzo-p-dioxins (PCDD) has been at the forefront of public and regulatory concern, because of the toxicity associated with particularly the 2,3,7,8-(laterally) substituted congeners, which have a tendency to bioaccumulate throughout the trophic food chain. Contamination of aquatic sediments by dioxins includes both non-point (e.g., atmospheric deposition) and point sources (e.g., industrial effluents, combined sewage overflows), and is generally characterized by a dominance of hepta- and octa-CDD, with minor contributions of hexa- to tetra-CDD [429]. Elevated concentrations of the 2,3,7,8-TCDD isomer tend to be associated with direct discharge from sources such as 2,4,5-trichlorophenol production [54,430]. 

Production, Use, Release, and Disposal. Production methods for 1,2-diphenylhydrazine are well described in the literature (including he patent literature) there does not appear to be a need for further information in this area. Uses of 1,2-diphenylhydrazine are documented but no recent production figures or detailed descriptions of uses are available. This information is useful for estimating the potential for environmental releases from manufacturing and use industries as well as the potential environmental burden, but it is difficult to obtain in the detail desired since it is considered confidential business information for those industries that manufacture... 

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