We are going to explain how waste water is
treated to become purified water that can be
safely put back into the river.
WATER - TREATMENT PLANT
Waste water or sewage is collected from agriculture, industry and
domestic use in Calahorra, Autol, Quel and Arnedo and taken to the
COLLECTING OF WATER
In the Plant it is mixed with rain water
that has been collected from the streets of
Calahorra, Autol, Quel and Arnedo
through the storm drain.
1. SOLIDS ELIMINATION
Water is pumped and forced to pass through 2 different
grilles: the first one, holds back big solids floating on
water; the second, smaller ones.
2. DEGREASING AND DESANDING
Then water is treated to remove sand
and oils. Oil is the pollutant most
difficult to get rid of.
3. COLLECTING OF SOLIDS, SANDS AND OILS
Solids, sands and oils are later
compacted and deposited in a
1. PRIMARY DECANTATION
The water passes to a
decantation tank outdoor for
the solid subtances fall at
bottom, and form the primary
2. BIOLOGICAL TREATMENT
Now, it is time to remove organic matter.
There are two types of bacteria that can do
- First, anaerobic bacteria digest organic
pollutants without oxygen.
- Later, aerobic bacteria digest the remains
in the presence of oxygen.
3. SECONDARY DECANTATION
The water is separated from
the sludge produced for the
bacterial action, and form the
4. SLUDGE TREATMENT
As a result of bacterial
digestion two different
substances are produced:
methane and compost.
5. GAS LINE
Compost is used in agriculture as a natural
Methane is stored and used to produce
Finally the filtered and disinfected
water is poured into the river.
This project has been realized by: