Zero-waste operations

Environmental Trends Toward Zero Waste Operation... 

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. 

The BASF refinishing system seems to offer quality, energy efficiency, economy, and speed for the small businessman operating a local body shop, while respecting the health and safety of the workers in this establishment and the environment in which these products are manufactured and used. The lower VOCs and almost zero-waste generated in production of this suite of products makes the BASF facility a less attractive target for those seeking to cause accidents with catastrophic consequences. 

Internally, molecules can be represented several different ways. One possibility is to use a bond-order matrix representation. A second possibility is to use a list of bonds. Matrices are convenient for carrying out mathematical operations, but they waste memory due to many zero entries corresponding to pairs of atoms that are not bonded. For this reason, bond lists are the more widely used technique. 

Each industrial subcategory is broken into core and additional allocation operations. The core is defined as those operations that always occur in the subcategory or do not affect the waste-water characteristics from the subcategory facilities (e.g., dry operations, zero-pollutant-allocation operations, or operations that contribute insignificant pollutants and wastewater volume in comparison with other streams). These operations that do not contribute to the wastewater characteristics will not occur at every plant, which should not affect wastewater treatment. 

It is not currently feasible to achieve a zero discharge of chemical pollutants from metal finishing operations. However, substantial reductions in the type and volume of hazardous chemicals wasted from most metal finishing operations are possible.8 Because end-of-pipe waste detoxification is costly for small- and medium-sized metal finishers, and the cost and liability of residuals disposal have increased for all metal finishers, management and production personnel may be more willing to consider production process modifications to reduce the amount of chemicals lost to waste. 

According to the developer, installation costs are low because no excavation or drilling is required, and no secondary waste is generated. Operating costs are minimal because the system requires no site power and the components need relatively zero maintenance (D192921, p. 3). 

Superficially, eqs. (3.1.11-12) seem to imply that diagonalization could be achieved in n(n - l)/2 steps. However, every time a rotation is used to set a specific At to zero, previously zeroed elements in the same row and column will be destroyed. This observation also hints at the proper selection of which element to eliminate in each step It is wasteful to spend operations on a rotation to eliminate a very small element which will anyway later get destroyed, so we should eliminate one of the largest elements. The best choice is usually the largest element however, for any but the smallest matrices, it takes more time to search for the largest element than to perform the rotation. Common practice is to simply loop over all elements in a predetermined order, but to slap the rotation for elements which fall below a certain threshold. This threshold is then successively lowered before each such sweep. Its value is based on the non-diagonality measure (3.1.6) (due to . Neumann) or some other convenient measure. 

Zero-valent iron is a promising in situ remediation technology for the degradation of many common pollutants, as it is comparatively inexpensive, does not restrict land use, and requires no energy for operating. Zero-valent iron has been successfully utilized to destroy trichloroethenes, chromate, chlorinated organics, and mixed wastes. It is capable of reducing and... 

The ELF is the amount of waste produced by the process per unit mass of the product. It can refer to individual stages in the synthesis or the whole process. In the ideal situation, where all the ingredients are converted into the product, the ELF value will be zero. This does not happen in synthetic processes. In pharmaceutical processes, the ELF is usually of the order of 100. The process design chemists will aim to minimize the ELF in order to reduce expense by selection of the reactions and the operation of the plant. 

The objective of the development reported here is to reduce tradional gas producer technology to commercial practice so that unattended biomass utilization systems under completely automatic control can be available to boiler operators now burning fluid fuels in packaged steam and heat generators. The system is to be designed for maximum gas production with minimum carbon remaining in the ash and zero liquid wastes production. 

Further progress is expected from new developments and combinations of processes. Thus, it would be possible to make the disposal of the gaseous (and highly pure) waste gas streams (residual propane content of the propylene feed) cost-effective and a source of electric power by connection to novel, compact, membrane fuel cells. Potential synergisms would also occur in the operating temperature of the cells (medium-temperature cells at 120 °C using the residual exothermic heat of reaction from the oxo reaction), the membrane costs by means of combined developments (e.g., for membrane separations of the catalysts [22]), and also in the development of the zero-emission automobile by the automotive industry. The combination of hydroformylation with fuel cells would further reduce the E-factor - thus approaching a zero-emission chemistry. ... 

---