Waste, combustion minimization

The major emissions from the combustion of fuel are C02, SO, NO and particulates14. The products of combustion are best minimized by making the process efficient in its use of energy through efficient heat recovery and avoiding unnecessary thermal oxidation of waste through minimization of process waste. Flue gas emissions can be minimized at source by ... 

Hasselrijs F (1988), How control of combustion, emissions and ash residues from municipal solid waste can minimize environmental risk" p.154-167 in AICHE Symposium Serie 84(265), Resource Recovery Municipal Solid Waste... 

All Subtitle C hazardous wastes are prohibited from land disposal without prior demonstration that hazardous constituent concentration levels comply with regulatory limits or that prescribed methods of treatment are used. These two criteria are intended to reduce the toxicity of the waste or substantially reduce the likelihood of migration of hazardous constituents from the waste, so that health and environmental threats are minimized. The primary method of treatment is waste combustion to destroy organic constituents. 

The utility system also creates waste through products of combustion from boilers and furnaces and wastewater from water treatment, boiler blowdown, etc. Utility waste minimization is in general terms a question of ... 

Air pollution from this process is a minimal problem because all waste gases are burned for fuel value or flared. The products of combustion of the... 

The key to efficient destruction of liquid hazardous wastes lies in minimizing unevaporated droplets and unrcacted vapors. Just as for the rotary kiln, temperature, residence time, and turbulence may be optimized to increase destruction efficiencies. Typical combustion chamber residence time and temperature ranges arc 0.5-2 s and 1300-3000°F. Liquid injection incinerators vary in dimensions and have feed rates up to 1500 gal/h of organic wastes and 4000 gal/h of aqueous waste. 

Combustion To minimize the hazards posed by the burning of hazardous waste, RCRA imposes strict standards on units conducting such combustion. 

The CAA compliance deadline may cause companies to install simple end-of-pipe emissions controls, instead of pollution prevention process changes. In order to limit this practice and encourage waste minimization, U.S. EPA allows owners and operators of combustion facilities to request a one-year extension to the compliance period in cases where additional time is needed to install pollution prevention and waste minimization measures that reduce the amount of hazardous waste entering combustion feedstreams.16 Requests for a one-year extension must reasonably document that the waste minimization measures could not be installed in time to meet the three-year compliance period. Decisions to grant the extensions will be made by U.S. EPA or authorized state programs. 

When viewing effluent treatment methods, it is clear that the basic problem of disposing safely of waste material is, in many cases, not so much solved but moved from one place to another. If a method of treatment can be used that allows material to be recycled, then the waste problem is truly solved. However, if the treatment simply concentrates the waste as concentrated liquid, slurry or solid in a form, which cannot be recycled, then it will still need to be disposed of. Landfill disposal of such waste is increasingly unacceptable and thermal oxidation causes pollution through products of combustion and liquors from scrubbing systems. The best method for dealing with effluent problems is to solve the problem at source by waste minimization, as will be discussed in Chapter 28. 

Also, by the very nature of chemical transformations, there are almost always unused chemicals remaining. These chemical leftovers include contaminants in the raw materials, incompletely converted raw materials, unavoidable coproducts, unselective reaction by-products, spent catalysts, and solvents. There have long been efforts to minimize the production of such waste products, and to recover and reuse those that cannot be eliminated. For those that cannot be reused, some different use has been sought, and as a last resort, efforts have been made to safely dispose of whatever remains. The same efforts apply to any leftovers from the production of the energy from the fuels produced or consumed by the processing industries. Of particular immediate and increasing concern are the potential detrimental effects of carbon dioxide emissions to the atmosphere from fossil fuel combustion, as discussed further in Chapters 9 and 10. 

Abstract Coal extraction and combustion produce a number of waste streams, some of which can be utilized. Fly ash from the combustion of pulverized coal is characterized it finds application as a partial replacement for Portland cement in concrete. Relatively few uses exist for other wastes, much of which is stockpiled, stored, or landfilled. These leave a legacy for future generations that must be managed to minimize geochemical impacts on air, soil, and groundwater quality. 

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