Physical , Chemical , and Biological Properties of MSW：物理化学和生物特性垃圾.ppt

1、Physical, Chemical, and Biological Properties of MSW,Why these need to be known,To develop and design integrated solid waste management systems.,Physical Properties of MSW,Specific weight Moisture content Particle size and size distribution Field capacity Compacted waste porosity,Specific Weight,Def

2、ined as weight of a material per unit volume (lb/yd3 or kg/m3) Table 4-1 shows typical specific weight and moisture content data for SW. MSWs in compaction vehicles vary from 300 to 700 lb/yd3; a typical value is about 500 lb/yd3 (296.65 kg/m3,Moisture Content,The wet-weight moisture content,where:

3、d = weight of sample after drying at 105C for 1 hr,See Example 4-1: Moisture content estimation,Particle Size and Size Distribution,Equations 4-2 to 4-6 Figure 4-1 to 4-4,Field Capacity,Total amount of moisture that can be retained in a waste sample subject to the downward pull of gravity Important

4、in determining the formation of leachate in landfills as water in excess of the field capacity will be released as leachate Typical value for the uncompacted commingled wastes is 50-60,Permeability of Compacted Waste,Governs the movement of liquids and gases in a landfill,Cd2 is the “intrinsic (or s

5、pecific) permeability” and depends solely on the properties of the solid material,Chemical Properties of MSW,The four most important properties if solid wastes are to be used as fuel are; Proximate analysis Fusing point of ash Ultimate analysis (major elements) Energy content,The major and trace ele

6、ments are required if the MSW is to be composted or used as feedstock,Proximate Analysis,Moisture (moisture lost after heated at 105C for 1 hr.) Volatile combustible matter (additional loss of weight after ignited at 950C) Fixed carbon (combustible residue after volatile matter removal) Ash (weight

7、of residue after combustion,See Table 4-2,Fusing Point of Ash,Temperature at which the ash resulting from the burning of waste will form a solid by fusion and agglomeration,Typical values range from 1100 to 1200C,Ultimate Analysis of Solid Waste Components,Involves the determination of the percent C

8、, H, O, N, S, and ash Due to the chlorinated compounds emission, the determination of halogens is often included. Moreover, they are used to define the proper mix of waste materials to achieve suitable C/N ratios for biological conversion processes,Table 4-3 to 4-4 and Example 4-2,Energy Content of

9、Solid Waste Components,Determined by; A full scale boiler as a calorimeter A laboratory bomb calorimeter (Table 4-5 and Example 4-3) Calculation, if the elemental composition is known (Example 4-4,Essential Nutrients and Other Elements,Required if MSW will be transformed biologically, e.g. used as f

10、eedstock, compost. See Table 4-6,Biodegradability of Organic Waste Components,Biodegradability of MSW is often determined from the VS content, by ignition at 550C. However, some MSW; e.g. newsprint and certain plant trimmings, are highly volatile but low in biodegradability. Lignin content can be alternatively used to estimate the biodegradable fraction (Table 4-7,Physical Transformations,Component separation Mechanical volume reduction Mechan