Processes zero-waste

The surviving U.S. plants have embraced all types of waste treatment processes (see Wastes treatment, hazardous waste Wastes, industrial). The most desired poUution prevention processes are those which reduce the total amount of waste discharged. Treatment and disposal are less strongly emphasized options. Zero wastewater discharge faciHties and water recycling processes are becoming more common (55,56). 

A major advantage of plasma processing is that the heat input may be accomplished in an atmosphere of any desired composition and reactivity. In practice there are only a few variations of chemical strategies available for thermal processing i.e. pyrolysis, oxidation, reactions with hydrogen and water. They were already reported elsewhere [5]. The most cost effective and friendly to the environment are the approaches of plasma employing for zero-waste fuel generation or for zero-waste incineration. 

Figure 1. Flowchart of plasma zero-waste fuel generation process...

Short residence time, minimal downstream separation, energy efficient, zero waste, low inventory, improved intrinsic safety, improved process flexibility, reduced area required, rapid product grade change, rapid response to market needs, improved control. 

The Green Chemistry Institute (GCl) Pharmaceutical Roundtable has used the Process Mass Intensity (PMl) [12], defined as the total mass used in a process divided by the mass of product (i.e. PMl = E factor -i- 1) to benchmark the environmental acceptability of processes used by its members (see the GCl website). The latter include several leading pharmaceutical companies (Eh Lilly, GlaxoSmithKline, Pfizer, Merck, AstraZeneca, Schering-Plow, and Johnson Johnson). The aim was to use this data to drive the greening of the pharmaceutical industry. We believe, however, that the E factor is to be preferred over the PMl since the ideal E factor of 0 is a better reflection of the goal of zero waste. 

Federal, state, and local governments are demanding more and more information from manufacturers not only the size, composition, and properties of waste streams that are generated, but also what chemicals are added to the process to manufacture the final product, and descriptive information on how these chemicals are used within the process. The third major driver for pollution prevention, then, becomes control of the business. When a business does not make any waste or is below a de minimus level, then only a minimum amount of information is required by the governing bodies hence, business information is conserved. Thermodynamic principles govern that zero waste is not possible, and the technical challenge is develop manufacturing processes that produce minimum waste. 

The environmental group Grassroots Recycling Network is developing a Zero Waste Policy Paper for consumer products. The net result is that society is beginning to expect that the products and processes of the future will not generate waste and are recyclable or biodegradable. 

By a systems approach, a process is designed as a complex system of interconnected components so as to satisfy agreed-upon measures of performance, such as high economic efficiency of raw materials and energy, down to zero waste and emissions, together with flexibility and controllability faced with variable production rate. 

Solvent is easily removed owing to its zero surface tension, leaving the product in an easily processable, clean and solvent-free form Recyclability, and therefore near zero waste production... 

Industry is seeking high yield, zero waste processes. Companies are evaluating the replacement of some base metal catalysts by more selective precious metal catalysts to eliminate troublesome by-product formation and/or contaminated waste waters. In the case of Chlorofluorocarbons (CFC s) industry is trying to develop cost effective processes to manufacture non-toxic Hydrofluorocarbons (HFC s) of zero ozone depleting potential to replace existing CFC s. 

Development of catalysts to make processes with zero waste and 100% selectivity possible... 

The greatest impact of catalysis will be in the development of new processes with essentially zero waste. Clearly the best approach is to develop processes with very high single pass yields. Often this is not possible so all waste and byproducts must be handled in an environmentally acceptable fashion. Some v te can be incinerated. Another approach is to convert it to salable products. Catalysis plays a key role in the conversion to salable products as illustrated by examples from our nylon 6.6 process. 

The overall production process for bioethanol has a clear advantage over some other industrial fermentation products. Due to the fact that all the input streams are converted to products such as bioethanol, gluten or a protein-rich feed stuff, so-called DDGS (distillers dried grains with solubles), fertilizer and a readily biodegradable wastewater the process can be seen as a zero-waste-concept. 

Monsanto has developed and implemented an alternative DSIDA process that relies on the copper-catalyzed dehydrogenation of diethanolamine. The raw materials have low volatility and are less toxic. Process operation is inherently safer, because the dehydrogenation reaction is endothermic and, therefore, does not present the danger of a runaway reaction. Moreover, this zero-waste route to DSIDA produces a product stream that, after filtration of the catalyst, is of such high quality that no purification or waste cut is necessary for subsequent use in the manufacture of Roundup . The new technology represents a major breakthrough in the production of DSIDA, because it avoids the use of cyanide and formaldehyde, is safer to operate, produces higher overall yield, and has fewer process steps. 

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