Bilbao, (EFE) from the place and come out drinkable from the tap, previous mandatory stop for treatment.
The water supply to the population of the Busturialdea-Urdaibai region is not carried out through systems based on reservoirs, but through some sixty collection points between rivers, streams and springs distributed throughout the area, whose flow is usually reduced in summer due to the lack of rain.
In some of these catchments, the Neiker agri-food and livestock research and development center leads the Life Urbaso project focused on water quality, in which the UPV/EHU, the BC3 Basque Climate Change Research Center, the Consortium of Aguas Bilbao Bizkaia and the Efe Agency.
The water begins the journey
In these streams and springs, the water that supplies the homes of the inhabitants of the region begins its itinerary, after having been subjected to purification in one of the seven treatment systems available to the place.
The deputy director of Supply Exploitation of the Biscayan Water Consortium, Iñigo Otaola, explained to EFE that the water catchments from which the population of Urdaibai is supplied are mostly superficial and “suffer from problems such as the availability of resources in time of low water”.
“When there is no rainfall, they dry up remarkably quickly and when there is very significant rainfall we have quality problems with cloudy resources,” he indicated.
Urdaibai is a forest area with non-native plantations -pine, eucalyptus-, which are periodically cut down and extracted, which causes “the passage of trucks, movement of land on forest tracks…”
“The direct consequence -he has pointed out- is that when rainfall occurs there is a very significant clouding of the resources that does not allow these waters to be made drinkable temporarily” and that increases the cost and intensity of the necessary treatment.
Urban Life Project
In the area, the scientific staff working on the Life Urbaso project, which has European funding, intends to demonstrate that carrying out a different forest management in Urdaibai, with an alternative forestry and care of the land so that less sediment reaches the water catchments , the quantity and quality of this resource can be improved and the physical-chemical treatment necessary for its purification can be reduced.
The head of purification of the Bilbao Bizkaia Water Consortium, Mikel Bartolomé, next to the water decanter in the middle of Urdabai. Water is a precious and valued asset in an area with a deficit of this resource, such as Biscayne in the Urdaibai Biosphere Reserve, in whose rivers and streams the journey begins until it reaches the furthest village from the place and comes out drinkable from the tap. , prior mandatory stop for treatment. EFE/Luis Tejido
At the foot of one of these catchments, in the bed of the Mape de Busturia stream, the person in charge of the Exploitation area of the primary supply network of the Biscayan Water Consortium, Jon Gorriti, has assessed actions of this type during a visit to the place carried out with colleagues from the entity and the Efe Agency.
“Any action that preserves against problems that may occur upstream of the catchment and that controls the vegetation that may exist and associated with it, the permeability of the land so that the circulating flows at the catchment point are as stable as possible, logically It is an action that will have a positive effect on the treatment” of water.
At the aforementioned point of the Mape stream there is a small and hidden filter that allows part of the water that runs between rocks and vegetation to be channeled towards the network that connects with the station where it is treated.
At the treatment station
At the Busturia DWTP -Drinking Water Treatment Station-, the water remains for hours until it comes out and is ready to be consumed.
From the moment a drop of water enters the plant until the supply comes out, “the normal water retention time is between 14 and 20 hours” at the facility, the head of purification of the Bilbao Water Consortium explained to Efe. Biscay, Mikel Bartholomew.
The one in Busturia is a plant that has a treatment capacity of between 10 and 20 liters per second. At its facilities, the “raw water” that comes from springs or streams is received to undergo the purification process that eliminates substances or elements that are potentially dangerous to health.
For example, “the colloidal and suspended matter that raw water brings in different amounts depending on the time of year” is eliminated, which is much greater in periods of rain, which complicates treatment and makes it more expensive.
Upon arrival at the DWTP, an oxidant is dosed and the water then goes to a facility that acts as a decanter to separate substances. A coagulant is administered in this tank, which has the effect of grouping the small suspended particles present in the water into larger particles.
Treatment Process
When it rains a lot and the “raw water” has a significant concentration of solids, the dosage of coagulant “can multiply by fifteen or twenty the price per cubic meter”, as Bartolomé has revealed.
The thicker particles due to the effect of the coagulant have more weight and due to the action of gravity go to the bottom of the settling tank, in the upper part of which the water is already “clarified, completely transparent”.
The decanted water then goes through sand filters, in which those particles “that may have escaped from the decanter” are eliminated, and then “the disinfectant is dosed so that the water supplied in the network is completely sterilized and residual chlorine reaches the last points of the network” in order to ensure that drinking water has been properly disinfected.
In any case, and “come the raw water as it comes”, the quality of the resulting water, which finally reaches the consumer’s tap, is the same and is guaranteed, they affirm in the Water Consortium. EFE