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

Systems Analysis of Zaragoza UWS
Guillermo Penagos
mostly available only in hard copies. When specific information concerning Zaragoza
system was not available, the extrapolation of general information has been considered.
3.2.4 Data analysis
A water balance was performed from the information available at Zaragoza municipality
(figure 2, and annexes). Mass balances were performed for BOD 5 , COD, TN, TP and
Heavy metals at the WWTPs. As shown in Annex 1 there are several processes for
which there are no data available at Zaragoza municipality. For such processes,
assumptions and extrapolations from literature values were made. A description of these
assumptions and calculations is provided next.
3.2.4.1 Storm water
No data concerning storm water quality exits in Zaragoza (which is understandable for a
semiarid region) therefore the possible effects of storm water upon WWT performance
are completely unknown. The possible effect of storm water upon the Ebro River is here
extrapolated from the chemical characteristics of sewage and the possible overflows,
which have not been actually measured, but have been estimated as follows (for raw
data and calculations for storm water refer to annexe 10):
Estimated storm water = Precipitation * impervious area
Overflows = Estimated storm water + Expected WWTPs inflow – Actual inflow to WWTPs
Daily precipitation data for Zaragoza was provided by the Local Agenda 21 Office at
Zaragoza municipality. There were no data concerning evaporation, extrapolation was made
from Marti (2000).
3.2.4.2 Energy consumption and CO 2 emissions from transportation
Environmental impacts derived from transporting both chemical products and sludge
were calculated as energy consumption and CO 2 emissions to the atmosphere. Factors
from Thonstad (2005) were used (for raw data and calculations refer to annex 9)
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