Recovery technical process options

Figure 1 shows the range of technical process options in resource recovery. Three broad technologies are available to recover energy and energy intensive materials from urban wastes mechanical, thermal, and biological. 

Fine and specialty chemicals can be obtained from renewable resonrces via multi-step catalytic conversion from platform molecules obtained by fermentation. An alternative method decreasing the processing cost is to carry out one-pot catalytic conversion to final product without intermediate product recovery. This latter option is illustrated by an iimovative oxidation method developed in our laboratory to oxidize native polysaccharides to obtain valuable hydrophilic end-products useful for various technical applications. 

This study focuses firstly on the transfer of regeneration principles as they have been developed in the field of water-based electroplating and of purification options for ionic liquids as they are experienced in other fields of ionic liquid application. A number of purification procedures for fresh ionic liquids have already been tested on the laboratory scale with respect to their finishing in downstream processing. These include distillation, recrystallization, extraction, membrane filtration, batch adsorption and semi-continuous chromatography. But little is known yet about efficiency on the technical scale. Another important aspect discussed is the recovery of ionic liquids from rinse or washing water. 

In the United States, landfill disposal still accounts for the majority of MSW and therefore for plastic waste as well. Mechanical recycling and incineration (waste to energy processes or WTE) are also in use, but to a much lesser extent. In Europe, whatever is not recycled is mostly incinerated for energy recovery. Feedstock recovery, though an attractive option, is not practiced as a laige-scale MSW treatment option. Figure 9.5 summarizes the available technical options for recovery of plastics waste. 

The other options include enhanced recovery of elemental chlorine and its conversion to another product. We might include, under enhanced recovery, the addition of higher-severity stages to a liquefaction plant. While this is more correctly a reduction in the amount of chlorine present in the tail gas rather than its recovery, it is a viable retrofit technique and one that has been used to replace some of the older recovery plants. A unit quantity of refrigeration becomes more expensive, hydrate accumulation may be more troublesome, and some of the problems of deep liquefaction are exacerbated. TTiese are the normal effects of extending the process, and they add nothing new to the technical discussion on liquefaction. 

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