Example Problem Sample Solution
Problem restatement:
Using the data provided:
Calculate the composition of the generated waste.
To simplify the problem solution, assume that we are working with a 100 lb sample of disposed waste. All of the subsequent calculation will be based off of this assumption. This enables us to treat the individual component data as weight (lb) rather than %.
1. Account for the Food waste ground up:
FWgenerated = FW disposed/(Fraction of generated food waste which is disposed)
FWdisposed =9.0 lb
Fraction of FW disposed
= (20/100 homes with food grinders)(75lb/100lb of food waste is disposed ground)+(80/100 homes without food grinders)(100lb/100lb of food waste is ground)
= 0.95 (conversely, Fraction ground = 0.05)
FWgenerated = (9 lb/0.95)
= 9.5 lb
Then,
Ground Food Waste = 9.5-9.0 lb = 0.5 lb(Diverted=Gen-Disp-Recy)
2. Now, remembering Eqn A above, if 11% of the generated waste is recycled then, 89% of the generated waste must be diverted and disposed.
3. Setup a computation table to calculate the generated waste composition
| Component | Disposed Waste (lb) |
Ground Food Waste (lb) |
Recycled Material (lb)1 |
Generated Waste (lb) |
Generated Waste (% by wt.) |
| Food Waste | 9.0 |
0.5 |
9.5 |
8.4 |
|
| Paper | 34 |
6.25 |
40.25 |
35.6 |
|
| Cardboard | 6.0 |
1.25 |
7.25 |
6.4 |
|
| Plastic | 7.0 |
0.75 |
7.75 |
6.9 |
|
| Textile | 2.0 |
2.0 |
1.8 |
||
| Rubber | 0.5 |
0.5 |
0.4 |
||
| Leather | 0.5 |
0.5 |
0.4 |
||
| Yard Waste | 18.5 |
1.0 |
19.5 |
17.3 |
|
| Wood | 2.0 |
2.0 |
1.8 |
||
| Glass | 8.0 |
2.25 |
10.25 |
9.1 |
|
| Tin | 6.0 |
0.5 |
6.5 |
5.8 |
|
| Aluminum | 0.5 |
0.13 |
0.63 |
0.6 |
|
| Other Metals | 3.0 |
0.38 |
3.38 |
3.0 |
|
| Dirt, Ash, etc. | 3.0 |
3.0 |
2.7 |
||
| Totals |
100 |
12.5 |
113.0 |
100.0 |
1Individual Recycled Materials calculated from total weight recycled (12.5 lb) multiplied by the percentage of the individual material (example: Paper = 50*12.5/100)