Question

1. Compare the volume occupied by 1000 lb of refuse before (loose) and after baling by calculating the compaction ratio.

a. List waste densities (loose and baled) and provide a reference.

b. Calculate the compaction ratio.

Refuse composition (percent by weight)

Newspaper	21%
Office paper	15%
Cardboard	8%
Glass	12%
HDPE	3%
PETE	3%
Steel cans	5%
Yard waste	18%
Aluminum cans	4%
Misc.	11%

Answer 1

Ans (a) Waste densities of loose and bailed according to Municipal Waste Characteristics and quantities Chapter 2, Table 2-4 as follows ,

Refuse	Weight (%)	Loose Density(LD) (lb/yd3)	Baled Density(BD)(lb/yd3)	W/LD	W/BD
News paper	21	55	1000	0.381	0.021
Office paper	15	400	750	0.0375	0.02
Cardboard	8	350	350	0.0228	0.0228
Glass	12	700	2700	0.017	0.00044
HDPE	3	24	65	0.125	0.046
PETE	3	40	500	0.075	0.006
Steel cans	5	150	850	0.033	0.00588
Yard Waste	18	500	500	0.036	0.036
Aluminium cans	4	74	250	0.054	0.016
Misc.	11	300	1000	0.0366	0.011

Total 100 0.818 0.185

So, loose bulk density can be can be calculated (_bulk) = 100 / 0.818

=122.25 lb /yd³

So, volume occupied before bailing = mass / density

= 1000 / 122.25

= 8.18 yd³

Density after bailing (_c) = 100 / 0.185

=540.54 lb /yd³

So, volume occupied after bailing = 1000 / 540.54

= 1.85 yd³

Ans (b) Hence, compaction ratio = density after bailing / density before bailing

= 540.54/ 122.25

= 4.42

Compaction ratio can also be calculated from volume occupied by 1000lb of refuse as follows:

Compaction ratio = volume before bailing / volume after baling

= 8.18 / 1.85

= 4.42