Waste processing INDEX

IAEA Technical Reports Series No. 431. 2005. Application of Membrane Technologies for Liquid Radioactive Waste Processing, pp. 1-145. Consultants Pabby A.K., Kohout R. (Canada), and TapseU G. (AustraUa) [http /www.iaea.org/Publications/index.html]. 

FIGURE 26.1 Water desalination costs as a function of salt concentration. (From IAEA Technical Reports Series No. 431, Application of membrane technologies for liquid radioactive waste processing, 2005, pp. 1-145. http //www.iaea.org/Publications/ index.html (accessed January 16, 2014).)... 

The Separation Stage. A fundamental quantity, a, exists in all stochastic separation processes, and is an index of the steady-state separation that can be attained in an element of the process equipment. The numerical value of a is developed for each process under consideration in the subsequent sections. The separation stage, which in a continuous separation process is called the transfer unit or equivalent theoretical plate, may be considered as a device separating a feed stream, or streams, into two product streams, often called heads and tails, or product and waste, such that the concentrations of the components in the two effluent streams are related by the quantity, d. For the case of the separation of a binary mixture this relationship is... 

Inputs and outputs assessed in mass balancing are shown in Figure 5.3. The software EATOS was used to calculate all mass balances of processes. Outputs of EATOS are the mass index (equation (5.1), mass of raw material per mass of product output), and the environmental factor (equation (5.2), mass of waste output per mass of product output). EATOS also allows the calculation of cost indices (e.g., reference [15]) (equation (5.3), cost of raw material per mass of product output). 

The EPA makes decisions about clean-up of abandoned hazardous waste sites under the so-called Superfund law. Risk assessment outcomes are one guide to the decision process. The agency has declared that, for carcinogenic contaminants, clean-up must reach lifetime risks somewhere in the range of one in 10 000 to one-in-one million most decisions seem to aim at risks of one in 100 000 or lower. Hazard index values for non-carcinogens are not expected to exceed one. Costs and technical feasibility figure heavily in these decisions. 

To demonstrate the ability of the Solvent Greenness Scoring Index to measure the greenness of a process, consider a hypothetical waste stream which contains 25 kg of four different solvents methanol, DMF, THF, and DGM. First the metric... 

In general, calculation of the risk or dose from waste disposal in the numerator of the risk index in Equation 6.2 or 6.3 involves the risk assessment process discussed in Section 3.1.5.1. As summarized in Section 6.1.3, NCRP recommends that generic scenarios for exposure of hypothetical inadvertent intruders at waste disposal sites should be used in calculating risk or dose for purposes of waste classification. Implementation of models describing exposure scenarios for inadvertent intruders at waste disposal sites and their associated exposure pathways generally results in estimates of risk or dose per unit concentration of hazardous substances in waste. These results then are combined with the assumptions about allowable risk discussed in the previous section to obtain limits on concentrations of hazardous substances in exempt or low-hazard waste. 

Process of Implementing the Waste Classification System. Taken together, the framework for waste classification discussed in Section 6.2 and the risk index developed in Section 6.3 and this Section constitute the foundations of a comprehensive and risk-based hazardous waste classification system. Such a waste classification system could be established by regulatory authorities using the following general process ... 

Use of the risk index in classifying waste is illustrated in Figure 6.2. Classification of waste essentially is a two-step process. The first step involves a determination of whether a waste can be classified as exempt, based on an assumed negligible risk and an exposure scenario for inadvertent intruders appropriate to disposal of waste in a municipal/industrial landfill for nonhazardous waste. If the waste is not exempt, the second step involves a determination of whether a waste can be classified as low-hazard, based on an assumed acceptable (barely tolerable) risk and an exposure scenario for inadvertent intruders appropriate to disposal in a dedicated nearsurface facility for hazardous wastes. 

As previously reported, membrane contactors present interesting advantages with respect to traditional units. Moreover, they well respond to the main targets of the process intensification, such as to develop systems of production with lower equipment-size/production-capacity ratio, lower energy consumption, lower waste production, higher efficiency. In order to better identify the potentialities of membrane contactors in this logic, they have been recently compared to traditional devices for the sparkling-water production in terms of new defined indexes [24]. In particular, the comparison has been made at parity of plant capacity and quality of final product. The metrics used for the comparison between membranes and traditional units are ... 

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