Page 270 - Materials Chemistry, Second Edition

258 LIFE CYCLE ASSESSMENT HANDBOOK

All activities that have a bearing on the management of solid waste, from
collection through transportation, recovery and separation of materials, treat-
ment, and disposal, are typically included in the LCA boundaries. It is usu-
ally assumed that waste material enters the system boundaries when it is set
out (or dropped off) for collection. Therefore, the life cycle burdens associated
with the production of garbage bags, garbage cans, compost and recycling
bins are typically not included in an LCA of end-of-life management options.
Similarly, the transport of waste by residents to a drop-off facility is typically
not included. It is often assumed that residents stop at waste drop-off facilities
on their way to somewhere else.
The functional elements of solid waste management include numerous
pieces of capital equipment, from refuse collection vehicles to balers for recy-
cled materials to major equipment at composting and combustion facilities.
As illustrated in Figure 11.4, resource and energy consumption and environ-
mental releases associated with the operation of equipment and facilities are
typically included an LCI.
For example, energy (fuel) consumed during the operation of waste col-
lection vehicles were included. It is also standard to include electricity
consumed for operation of the office through which the vehicle routes are
developed and the collection workers are supervised. Activities associated
with the fabrication of capital equipment, such as the collection vehicles
themselves, are typically included as their environmental burden is insig-
nificant when allocated over the life of the equipment and tonnage of waste
processed.
The resource and energy consumption and environmental releases associ-
ated with producing the material and energy inputs are included in the LCA.
For example, the resources and environmental releases associated with the
production of lime or other materials used for air pollution control at a WTE
facility are included. Similarly, the energy and emissions associated with the
production of diesel fuel consumed by collection vehicles and other transpor-
tation stages are included.

Energy Materials

1 f * r
¥ Energy
Waste (power/steam)
Solid waste - management
-► Recovered materials

Air emissions Residual wastes
Water pollution
Figure 11.4 Life cycle inventory elements for waste processes.