Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in
vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«.
30
Figure 5: Complete water scheme
The user thus not only becomes “consumer” of potable water but also producer of service water,
which he uses again for particular applications. Not only is the separation of water supply and
disposal removed because the user is an active and important link between the two lines, but even
the separation at the other end also disappears, because the sink for used water becomes source of
new water. The real system thus is much closer to Figure 5, a loop, or at least a cascade, where
one’s sink is the next one’s source. For optimisation of the water use, it is important always to
work at the whole cycle or all the steps of a cascade.
When the Water Supply and Sanitation Collaborative Council (WSSCC) set together at Bellagio
in 2000 to prepare recommendations for the UN General Secretary for the solution to the lack of
sanitation in developing countries, they came up with the household centred approach. The idea
SOURCE
USES
TREATMENT
(wastewater)
SINKS
TREATMENT
(supply water)
STORAGE
• Sourec
• Lake/
reservoir
• .....
• Reservoir
• Tank
• ....
• Filter
• Disinfection
• .....
• Domestic
• Industrial
• .....
• Channel
• Pipe
• .....
• Septic tank
• Biological
wastewater
treatment
• .....
• Soil
• River/drainage
canal
• .....
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in
vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«.
31
was that any sanitation issue should be addressed at the smallest possible level. Only if no solution
could be identified at the lowest level, the search should continue at the next higher level, from
household to neighbourhood to town, province and country or even trans-boundary river basin
(Figure 6).
Figure 6: Household centred approach (EAWAG 2005) for domestic wastewater
As shown above the household level is not only a key element for sanitation in developing
countries. This is true for the entire urban water cycle in any setup. The household on one hand is
user of water, and can use more or less. It can use the water mains or a choice of other sources,
e.g. roof or non-roof stormwater, treated greywater or wastewater, which significantly increases
the efficiency of water use (
Table
2
). On the other hand the household also becomes producer of a variety of flows, which can
be mixed or collected separately and used as service water, fertiliser, etc.
The equivalent of the household in production of goods is the process. One of the first cleaner
production initiatives was started in 1992 in Austria, predating the household centred approach.
Cleaner production has developed tools to design cascades and optimised multi-source systems
according to pre-selected criteria. Industry had learned from efficient energy use, resulting in the
heat pinch analysis, to do the same for water and developed the water pinch analysis (Wang and
Smith, 1994). This was further developed to the water management hierarchy (Manan et al., 2006)
and the cost-effective minimum water network resulting in the systematic hierarchical approach
for resilient process screening (SHARPS) (Wan Alwi and Manan, 2007). Why shouldn’t tools
Operacija se izvaja v okviru Operativnega programa razvoja človeških virov za obdobje 2007-2013, razvojne prioritete 3 : »Razvoj človeških virov in
vseživljenjskega učenja«; prednostne usmeritve 3.3 »Kakovost, konkurenčnost in odzivnost visokega šolstva«.
32
developed for water demand minimisation in industry be applicable to households? Actually
SHARPS was developed for both, industrial and domestic applications, but while applied in
industry has still to find its way into domestic urban water planning.
Table 2: Differential use of water resources, 1 preferred, 2 compatible, 3 non-preferred,
4 non compatible use (Ecological Engineering 2003)
Kitchen
Laundry
Bathroom
USE Garden
Cold
Hot
Cold
Hot
Toilet
Cold
Hot
SOURCE
Potable Water
3
1
2
1
2
3
1
2
Wastewater
Treated
Wastewater
1
4
4
4
4
1
4
4
Greywater
2
4
4
4
4
2
4
4
Stormwater
Roof
2
2
1
1
1
2
2
1
Non-roof
2
4
4
4
4
2
4
4
Figure
abovesuggests that there is a link between supply and disposal of water not only at the
user stage but also between the sink and the source of water. There are obvious examples of such a
closed cycle, e.g. when greywater is treated and used for laundry, which then is again collected as
grey water. Our existence in a finite environment however suggests that we are actually limited to
planned or un-planned reuse of actually any resource, including water. Authors speak of broken or
closed cycles. An overall optimisation is only possible, if the whole cycle from source to source,
in a cradle to cradle approach, is examined and dealt with.
All stakeholders, at every stage of the cycle, have to be involved and participate in order to make a
new solution possible, water supplier, user, wastewater utility, authority. Thus decision making
and design must be participatory and process oriented, as the processes have to be adapted to each
particular case, compared to using just one set of standard processes, which everybody knows
already before and reflection starts.