Environmental Engineering Reference
In-Depth Information
Table 6.5
Recycling options for an urban centre
Source of water
Feasibility
Re-use onsite of
domestic wastewater
Onsite treatment is possible but requires training and
commitment. Not a preferred choice.
Re-use onsite of large
building wastewater
Suitable for office or apartments blocks where an on-site
plant can be managed by trained staff and used for toilet
flushing, water features and air conditioning.
Re-use onsite of
industry wastewater
A likely option for large water users if cost structure
encourages it.
Sewer mining (use of
reclaimed water from
sewerage)
Technically feasible for industry re-use or for irrigation of
parks and sports grounds. Barriers are cost and consumer
acceptability.
Third pipe supply of
recycled water (use of an
additional pipe to
provide recycled water
to premises)
Used for agricultural irrigation. Technically feasible for
urban greenfield developments. Requires infrastructure at
development stage and appropriate pricing.
Collection of roof run-
off in tanks
Attractive to users and provides minor benefits to the water
supply by taking some pressure off water supply systems.
Use of stormwater
Requires storage in lakes or aquifers. Could be useful for
augmenting environmental flows or other uses.
costs $5-7/KL, and yet we sell it for 20c, and are then surprised when usage
increases? Why do we sell water from the same dam to irrigators for 20c a KL
and to urban residents for 80c, and then try to give them recycled water that
costs $5 a KL to produce? When do we install desalination plants and just use
seawater that can be produced for probably around $2/KL?
Recycled water is a major challenge to triple bottom line decision-
making. People feel strongly about protecting public health. They have great
concerns if recycled water is used for personal use but they are relaxed about
it in gardens and for toilet flushing. We have some acceptance of third pipe
systems to deliver recycled water to households. Balancing the various envi-
ronmental impacts such as impacts on coastal waters and impacts of energy
use on greenhouse gas are not easily costed and so are hard to consider in
economic, environmental and social assessments of such decisions.
Conclusions
Australia is entering a period of some water scarcity, and there are pressures
to use water more efficiently in both urban and rural Australia. Markets are
