Page 113 - Materials Chemistry, Second Edition

Life Cycle Assessment: Principles, Practice and Prospects
100

1 p
Reuse Feeder
Pump 100 kW
100%

720 kg 130 kg 42.5 kg 32 kg
Cast iron GG35 Steel (galvanised) Copper (primary; Aluminium
(IDEMAT) for wire) primary AU
26.8% 15.8% 16.3% 31.7%

350 kg 130 kg 32 kg
Steel cold rolled Aluminium
Oxysteel BOF primary AU
(BOF)
(disaggregated)
26.5% 13.3% 31.7%
Figure 8.5 Global warming impact breakdown of a sewerage pump (Hallmann et al. 2003).
IDEMAT, LCA database; AU, Australian Life Cycle Inventory dataset; BOF, Blast Oxygen Furnace.

8.3.2 Operation and consumption
Operational impacts of a water system predominantly relate to demand and are therefore
seasonal. Notwithstanding seasonality, the impacts of water servicing systems are typically
driven by water transport energy requirements (usually pumping) and water treatment require-
ments. Assessment of water treatment impacts usually requires assessment of energy require-
ments, chemical additives and chemical and biological emissions to the environment.
Pumping in water systems is typically undertaken with electric motors and centrifugal
pumps, although other methods exist. Pumping energy (P) can be calculated in several ways,
including:
r gQh
P = Equation 8.1
1000h
3
where: ‘r’ refers to the density of water which is 1000 kg/m , ‘g’ refers to the gravitational
2
3
constant which is 9.8 m/s , ‘Q’ refers to the discharge which will be 1 m /s, ‘h’ refers to the
pumping head, which also incorporates the efficiency loss of the pipe, and ‘h’ refers to the
combined pump and motor efficiency.
Table 8.2 Assumed life times for subsystems in a suburban water-serving model (Grant and
Opray 2005)
Infrastructure Life time modelled (years)
Household plumbing and infrastructure 25
Trunk mains (water and sewer) 70
Non-truck water and sewer mains 100
Water treatment facilities 60

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