Sohd waste

The top of the bench should always be kept clean and dry this can easily be done if a wet and a dry rag are kept at hand. Apparatus not immediately required (a) should be kept as far as possible in a cupboard beneath the bench if it must be placed on the bench, it should be arranged in a neat and orderly manner. All apparatus should be washed immediately after use and placed in a position to drain at the first opportunity, the apparatus should be dried. It must be emphasised that as a general rule a deposit of dirt or tar is more easily removed when it is freshly formed a suitable cleaning agent can usually be found while one still remembers the nature of the material or the circumstances attending its formation. It is hardly necessary to add that sohd waste and filter papers must not be thrown into the sink, and that all operations requiring the handhng of unpleasant and noxious materials sliould be carried out in the fume cupboard ( hood ). 

Other Plastics. A relatively small amount of poly(vinyl chloride) goes into packagiag appHcations and appears in municipal soHd waste (25). 

Each vehicle generates 500—800 pounds of residue. The aimual U.S. total is about 3.5 million tons or about 1.3% of the municipal soHd waste generated aimuaHy (3). The mixture is too complex to separate and recycle. Depending on the amount of glass, water, metal, and dirt present, the residue... 

EranMin Associates Limited, "Characterization of Municipal SoHd Waste in the United States, 1994 Update," Report No. EPA 530-94-042, Nov. 1994. 

MSW incinerators (qv) are typically designed to reduce the volume of soHd waste and to generate electricity in condensing power stations. Incineration of unprocessed municipal waste alone recovers energy from about 34,500 t/d or 109 million metric tons of MSW aimuaHy in some 74 incinerators throughout the United States. This represents 1.1 EJ (1.05 x 10 Btu) of energy recovered aimuaHy (18). Additionally there are some 20 RDE facihties processing from 200 to 2000 t/d of MSW into a more refined fuel (19). Representative projects are shown in Table 10. 

Includes fuelwood, charcoal bagasse, and animal, crop, pulp, paper, and municipal soHd wastes, but does not include derived biofuels. Sums of individual figures may not equal totals because of rounding. 

Municipal Solid Waste. In the eady 1990s, the need to dispose of municipal soHd waste (MSW) ia U.S. cities has created a biofuels industry because there is Htde or no other recourse (107). Landfills and garbage dumps are being phased out ia many communities. Combustion of MSW, ie, mass-bum systems, and RDF, ie, refuse-derived fuel, has become an estabhshed waste disposal—energy recovery industry. 

Ash Characteristics. The elemental ash composition of biomass waste and municipal soHd waste differs dramatically from that of coal (qv). ... 

It is useful to examine the combustion process appHed to soHd wastes as fuels and sources of energy. AH soHd wastes are quite variable in composition, moisture content, and heating value. Consequendy, they typically are burned in systems such as grate-fired furnaces or duidized-bed boilers where significant fuel variabiUty can be tolerated. 

Combustion characteristics of consequence include the overall mechanism of soHd waste combustion, factors governing rates of waste fuels combustion, temperatures associated with waste oxidation, and pollution-formation mechanisms. 

Temperatures Associated with Combustion. The temperatures achieved by soHd waste combustion are typically lower than those associated with fossil fuel oxidation, and are governed by the following general equation (1) ... 

Whereas soHd wastes can achieve significant flame temperatures, they are substantially below those associated with fossil fuels. These differences are... 

Given the mechanisms and temperatures, waste combustion systems typically employ higher percentages of excess air, and typically also have lower cross-sectional and volumetric heat release rates than those associated with fossil fuels. Representative combustion conditions are shown in Table 11 for wet wood waste with 50—60% moisture total basis, municipal soHd waste, and RDF. 

Ethanol can also be produced from cellulose (qv) or biomass such as wood (qv), com stover, and municipal soHd wastes (see Euels frombiomass Euels FROMWASTe). Each of these resources has inherent technical or economic problems. The Tennessee Valley Authority (TVA) is operating a 2 t/d pilot plant on converting cellulose to ethanol. 

Fig. 2. Generalized process flow chart for the thermal treatment of soHd wastes. To a certain extent, steps 2, 3, 4, and 5 always proceed in parallel because...

Vapor Pressures and Adsorption Isotherms. The key variables affecting the rate of destmction of soHd wastes are temperature, time, and gas—sohd contacting. The effect of temperature on hydrocarbon vaporization rates is readily understood in terms of its effect on Hquid and adsorbed hydrocarbon vapor pressures. For Hquids, the Clausius-Clapeyron equation yields... 

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