Systems Analysis of Zaragoza Urban Water - SWITCH - Managing ...

Systems Analysis of Zaragoza UWS
Guillermo Penagos
4.4.3.3.5 Effect of water recycling on pollution loads to the Ebro River
Under the assumptions previously described it is expected that 14% larger pollution
loads will be dumped into 14% less sewage volume by 2020. Hence BOD, nutrients
and heavy metals will be 28% more concentrated in the sewage. If industrial water
recycling is considered then pollutant concentrations in sewage will increase 30% for
10% recycling and 37% for 30% strategy. As consequence of this increased
concentration in the inflow, higher removal efficiency at WWTPs would be expected.
In order to calculate how much this increasing efficiency would be a regression
analysis between pollutant concentrations and removal efficiency was performed for
all WWT facilities in Zaragoza. However, no significant correlation was found (r 2 =
0.028, data not shown). Therefore, the assumption is made here that with the current
WWT technology and current societal production and consumption patterns, pollution
loads to the Ebro River will increase 14% by 2020, even if unaccounted water is
reduced and even if industrial water is recycled.
4.4.3.4 Assessment of water quantity and quality for Zaragoza in the
future
Considering the figures previously described for Sc3 concerning upstream water use
and the effect of climate change upon water availability in the Ebro catchment. An
assessment of the risk for water availability in Zaragoza was performed. Here an
additional scenario for the year 2060 was projected. From figure 24 it is evident that
Zaragoza can relay on Yesa reservoir as raw water source for the years to come
since Zaragoza requirements projected by the year 2060 with increasing population
and no water recycling are well below the projected capacity of the reservoir, even
under the worst climate change and water extraction scenario.
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