 Treatment Plant
7 Km further on, the next step is the Pretreatment Plant of La Telva.
Actually, EMALCSA's water
treatment takes place at three plants - Cañás, Telva 1 and Telva
2.
A total annual volume of 38 million m3 is pumped at the three
plants. The largest and most recent of the three plants is La Telva 2, which
treats just over 22 million m3. The total maximum capacity of the three plants
is 5,490 m3/hour.
 Physical
cleaning treatment - eliminates large items (rags, wood etc) and leaves,
with two grilles. The second grille has a cleaning system which maintains its
fine mesh constantly free of dirt.
Pumping
water to the next stage - with three vertical 4,000 litres/second
pumps.
Flocculating
settlers - there are two steps involved in this stage. Flocculation
is the process in which particles are gathered together on contact, caused by
special products called flocculants. The particles, now larger than before,
are deposited or collected afterwards. Slush accumulates at the bottom of the
settlers and is taken out automatically. The unit diameter is 24 m with an ascending
speed of 3.41-3.64 m3 per m2/hour. The power absorbed by the turbine is 3.6
HP.
Filters
- eight units measuring c.5 x 10 metres, a total surface area of over
400 m2. Filtering occurs at a speed of 6.48-5.92 m3 per m2/hour. The system
is totally automatic. Cleaning is by air and water.
Reactant
dosage and addition - the final step in water treatment consists of
the addition of a series of reactants which leave the water in the best possible
state. Dosage is automatic, according to water volume. The products used are
chlorine, aluminium sulphate at 8 % and polyelectrolite. To get an idea of how
much is used, the average dosis of chlorine is 2.02 gr/m3, which means a total
annual consumption of c. 78,250 kilograms (according to water volume).
The quality of the water obtained from this process is excellent.
Cloudiness is less than 0.2 p.p.m and colour less than 0.1 p.p.m.
Water quality is kept at optimum levels which fulfil all sanitation rules and
regulations. Samples are checked from water leaving the treatment plants and
in the distribution network. Surface water is analysed in the Barcés
and Mero rivers and in the reservoir at Cecebre. Sewage is also analysed at
the Bens purifier.
Once treatment is complete, the water, now drinkable, is pumped through an
800 mm diameter pipe with three pumps whose capacity is 1,440 m3/hour. Thus
is comes to the city, where it is distributed in three elevated tanks in Ventorrillo,
Monte Alto and Los Castros.
From here it comes to our homes by gravity, and we can make use of it.
 The Water Cycle
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