UNIT V PLEASE READ CAREFULLY
2-2 Municipal Solid Waste Generation
Generation and Management of Solid Waste in the United States from 1960 to 2012 (in pounds per capita per day)
1960 1970 1980 1990 2000 2005 2010 2012
2.68 3.25 3.66 4.57 4.74 4.69 4.44 4.38
0.17 0.22 0.35 0.64 1.03 1.10 1.15 1.14
Negligible Negligible Negligible 0.09 0.32 0.38 0.36 0.37 0.17 0.22 0.35 0.73 1.35 1.48 1.51 1.51
0.00 0.01 0.07 0.65 0.66 0.58 0.58 0.57 0.00 0.01 0.07 0.65 0.66 0.58 0.52 0.51
2.51 3.02 3.24 3.19 2.73 2.63 2.41 2.36
179 203.984 227.255 249.907 281.422 296.410 309.051 313.914
_ ::;= yard trimmings, food scraps, and other MSW organic material. Does not include backyard composting. :=r; stion of MSW in mass burn or refuse-derived fuel form, and combustion with energy recovery of source
-~_~ ...••..•.-z..erials in MSW (e.g., wood pallets, tire-derived fuel). - recovery minus combustion with energy recovery. Discards include combustion without energy recovery~ __ not add to totals due to roundinq.
MSW Generation, kg/per capita, Kaunas, LT,2010
~------------------~--------------~--- --- ~~-----------1r-:-------------;
• Hazardous • Wood • Terrapaks Other inorganic • Yard waste • Glass
• Other organic • Food waste • Other metals
• Ferrous metals • Plastics
Paper and cardboard
::xample for seasonal changes in household waste composition. Source: [32]
III WI ,. I
ctln om n '
ant 9 'f W dy bicm I~ s. In addition, in diff " II
~O%.47 discussed here make II
(anaerobic digestion < II I ere the specific organi I"
sd or isolated, and the pr« ::omposting and anaerohl
-sed of only one chemi ,
.e processes are numerou
as one would describe 'Iii
ANAEROBIC
ons (absence of free oxygen] ::::H
4 ), carbon dioxide (CO)
(NHJ, and a few others. T, ~l prompted wastewater trC,l1 waste solids and capture Ihl inery in the treatment plant ewater treatment plant is nllt J the potential for producin .erit. on dioxide can be calculaiul
II) 2 + dNH3
II If' (11 chemical compositioi
f I III I II~ urln the anaerobic
n ral formula for glucose is C6H,206; hence by the equation v , a = 6, b = 12, c = 6, and d = O.
II ° (24 - 12 - 12)H ° (24 + 12 - 12)CH (24 - 12 + 12)CO h " 6+ 4 2 ~ 8 4+ 8 2
,,""'12°6 ~ 3CH4 + 3C02 j(' that the equation balances. The molecular weights are 180 ~ (1 ) + 3(44); hence 1 kg of glucose produces 0.73 kg of CO2 and
() I kg of CH4• Recalling that 1 gram molecular weight of a gas at , I indard temperature and pressure occupies 22.4 liters, the pro- dll cion of CO2 and CH4 from 1 kg of glucose is 746 liters each of III hane and carbon dioxide.
1111(' rtunately, the chemical composition of MSW is difficult, if not impos- ", (I d t rrnine, although some attempts have been made to do so. The best
11111 IIIW tion is that the organic fraction of refuse can be described by the "t/1 II rmula C99H1490S9N. With this formula, the previous equation esti- II Ih. L the production of methane from a landfill is 257 liters of methane
, I II I ra m of wet refuse (total, organic plus inorganic, assuming wet refuse is , I, I I gradable organic). In using this equation, note that the only carbon
I 1,111 I rticipate in the production of gas is from decomposable materials, It I () d waste and paper. Other organics, most importantly plastics, do not 111" • to produce gas.
II,' two ways of generating methane are to capture the gases produced in 11111 r to digest organics in an anaerobic digester using tanks similar to those I 11 W stewater treatment plants or another structure, such as a horizontal orI" linder. Methane generation both in anaerobic digesters and in landfills
II I II. d in this section, although a more complete presentation of landfill gas ,,111I1 in is found in Chapter 8. Much of the following anaerobic decomposition 111\ liPI lies to both processes, however.
Anaerobic Decomposition in Mixed Digesters I 'III a ic metabolic pathways for the decomposition or degradation of wastes "lfl(,/e (with oxygen) and anaerobic (in the absence of oxygen). While an aerobic
( 111 ,iii ht be generally represented as 1"11111 organics] + oxygen ~ CO2 + Hp + NO; + SO~2 + other products