Useful products from waste

Early patents indicated that because water inhibits the aldol condensation mechanism, it was necessary to dry recycle acetone to less than 1% water (139—142). More recent reports demonstrate DAA production from waste acetone containing 10—50% water (143), and enhanced DAA production over anion-exchange resins using acetone feeds that contain 3—10% water (144,145). 

Finally, selective separation and dewatering of one suspended substance in a slurry containing different minerals or precipitates is possible by selectively adsorbing a magnetic material (usually hydrophobic) onto a soHd that is also naturally or chemically conditioned to a hydrophobic state. This process (Murex) was used on both sulfide ores and some oxides (145). More recently, hydrocarbon-based ferrofluids were tested and shown to selectively adsorb on coal from slurries of coal and mineral matter, allowing magnetic recovery (147). Copper and zinc sulfides were similarly recoverable as a dewatered product from waste-rock slurries (148). 

It has been shown, however, that such catalysts may contain protons, either by design or because of the difficulty in removing all traces of moisture, and these protons have been shown to be superacidic with Hammett acidities up to —18. These protons will also play some role in the catalytic activity of these ionic liquids in practical situations. Ionic liquids in which superacidic protons have deliberately been generated by addition of small amounts of water, HCl or H2SO4 have been used to catalytically crack polyethene under relatively mild conditions. The main products are mixed C3-C5 alkanes, which would be a useful feedstock from waste polyethene recycling. In contrast to other cracking procedures no aromatics or alkenes are produced, although small amounts of polycyclic compounds are obtained. 

Recycling is the use, reuse or reclamation of wastes after they have been generated. Through recycling and reuse, hazardous wastes are routed into production processes rather than being released to the environment. Reclamation is usually considered to be a part of recycling because it recovers raw material for reuse. The processes used to reclaim useful materials from waste often generate hazardous wastes of their own [16,17,20-23]. 

The experimental results in Figure 39.9 revealed that when the flow rate of the aqueous phase is higher than that of the organic phase in a hydrophobic membrane and with feed in 4 M HNO3 and 20% TBP as an extractant, the transport of uranium across the membrane is fast. Therefore, a HF contactor in strip dispersion mode with 20% TBP in nph as an extractant could be successfully used for the separation and concentration of U(VI) from nitric acid media. The feasibihty of this technique for the separation of U(VI) from dilute solutions using 0.01 M HNO3 solution as strippant even in the presence of fission products from waste streams makes it a viable alternative to conventional methods. 

Fuel Production from Wastes Using Molten Salts... 

This process will allow the recycling of solid waste to produce a useful product. High pressure and temperature combined with hydrogen can convert most types of domestic and industrial wastes back into products that are currently obtained from fossil coal and oil. No volatile polluting chemicals will be vented into the atmosphere. The metals can be recovered for further use and the ceramic materials will be converted into a product difficult to distinguish from natural rocks. This type of process will not solve all the solid waste disposal problems, but will provide a potential method for recovery of valuable products from waste. When implemented, it will dramatically reduce the amount of solid waste placed in landfills. This process also has the potential to reduce the amount of oil and coal mined to provide the carbon compounds needed to manufacture all petrochemical derived materials. This waste reduction process is a variation on the Fischer-Tropsch process, mentioned on page 101, in use commercially to produce hydrocarbon materials from coal. 

Phase-transfer catalysts are used to extract organic or pharmaceutical products from waste water and to transfer hydrophilic dyes from water into hydrophobic polymers... 

The use of recycled materials reduces waste shipped to landfills and cuts down on mining of clay and other minerals needed to make conventional tile. Recycling also reduces energy use because making a product from waste material typically requires less energy than fabricating one from raw materials. This, in turn, helps to slash fuel use in manufacturing and helps reduce environmental pollution. 

Jeong, T.-Y., Cha, G.-C., Yoo, I.-K., Kim, D.-J. (2007). Hydrogen production from waste activated sludge by using separation membrane acid fermentation reactor and photosynthetic reactor. International Journal of Hydrogen Energy, 32, 525—530. 

Industrial ecology is a new field based on chemical engineering and ecology its goal is to create products in a way that minimizes environmental harm. Therefore, environmental chemical engineers strive to build factories that use renewable energy as much as possible, recycle most materials, minimize wastes, and extract useful materials from wastes. In general. 

Shin, H.-Y., S.-H. Lee, J.-H. Ryu, and S.-Y. Bae. 2012. Biodiesel Production from Waste Lard Using Supercritical Methanol. Journal of Supercritical Eluids 61 134-138. 

Jeihanipour A, Aslanzadeh S, Rajendran K, Balasubramanian G, Taherzadeh MJ (2013) High-rate biogas production from waste textiles using two-stage process. Renew Energy 52 128-135... 

The principles of a sustainable society make us consider water-borne discharges from industries like pulp and paper as sources of useful chemicals rather than as wastes to be treated and disposed 4). By converting what is now considered as waste material into useful products, the waste producers, chemical manufacturers, and regulators are offered new opportunities. 

Environmental risk from partners is a powerful driver for restructuring the supply chain. There is growing recognition that issues of environmental pollution should be coordinated with the supply chain processes. Many European countries have enforced legislation that hold manufactures responsible for used-products and waste (Robeson et al. 1992 Fleischmann et al. 1997). Therefore, issues such as recycling, waste disposal, and control of industrial pollution must be addressed in an integral fashion (refer to Chap. 9). 

CO2 is a raw material, not a waste product. PLA uses it successfully as a raw material because the fermentation and chemical processing technologies are very efficient and have high yields. What additional technologies can create other useful products from CO2 Can fermentation technology be developed to fix CO2 ... 

The use of various pretreatments of the plastic wastes such as chemical soaking, heat treatments, microwave, and plasma treatments, etc. in conjunction with the pressurized method might be attractive areas for future research. Co-pyrolysis with other wastes such as food wastes is also plausible. Much work has been carried out on other pressurized carbonization methods such as biomass hydrothermal carbonization [111, 112]. If an industrial process is to emerge from the research, the combined use of various carbon sources would be attractive for economy-of-scale purposes. Producing porous carbons for further applications from plastic wastes would not only yield useful products from cheap precursors, but it would also help reduce the problems associated with the ever-growing plastic waste stream. 

WRAP [63] has also funded a project that uses rubber from waste tyres to product new flooring screed and plaster products. The products are generically known as Rubbercrete, with the plaster products containing 70% rubber crumb and the flooring screed 30% crumb. Rubbercrete is also available in a rapid set mix design, which has a crumb content of 35% and dries within two to three hours. 

Chakraborty, R., Sahu, H., 2014. Intensification of biodiesel production from waste goat tallow using infrared radiation process evaluation through response surface methodology and artificial neural network. Applied Energy 114, 827—836. Available at http //www. sciencedirect.eom/science/article/pii/S030626191300319X (accessed 01.03.15.). 

Sirisomboonchai, S., et al., 2015. Biodiesel production from waste cooking oil using calcined scallop shell as catalyst. Energy Conversion and Management 95, 242—247. Available at http //www.sciencedirect.coin/science/article/pii/S0196890415001570 (accessed 06.03.15.). 

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