Through Hugues-Olivier Dumez
Published on 9 Feb 21 at 7:02
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The passage near the place gives some gagging. The car drivers, on the device from Toulouse, have a brief glimpse of it as they walk along the Ginestous site.
Welcome to the wastewater treatment plant of Ginestous – Garonne. This treatment plant is the main place where the metropolis’ sewers converge.
–The equivalent of 950,000 inhabitants
Located near the Ernest-Wallon stadium, the plant has a treatment capacity of 950,000 population equivalents. “In total, 14 municipalities are connected to the Ginestous station”, details Robert Medina, vice-president in charge of water and sanitation at Toulouse Metropolis. “This represents 76% of the Toulouse metropolis”.
Some, in Toulouse, still remember the fire of 2014 where the deodorization facilities of the composting unit had been destroyed. Mingled with the hot summer heat, the emanations became unbearable for the inhabitants of the surrounding neighborhoods.
Less sludge to treat
This fire is now an old story. Several projects have also been launched in order to drive away bad smells on this site of about twenty hectares in Ginestous. A fight fought on several fronts at the same time, as explained Yoan Beaujon, plant manager:
The anaerobic digestion plant, in operation since September 2020, is starting to bear fruit. Since mid-October, the plant has supplied biogas, which comes from anaerobic digestion, to the city’s GRDF network. Enough to provide heating and hot water the equivalent of a municipality of 11,000 inhabitants or to be able to supply 230 buses for a year. In addition, this new process has enabled us to halve the volume of sludge, one of the causes of odor nuisance.
“The anaerobic digestion unit allows us to go from 16,000 tonnes of sludge per year to 8,000 tonnes”, emphasizes Robert Médina, for Toulouse Métropole water.
–Where does the sewers go?
To put it simply, the wastewater that arrives at the treatment plant crosses a first obstacle. A ” screening ”At the entrance to Ginestous allows particles larger than six millimeters to be exfiltrated, present in the effluents, at the factory entrance.
These large particles are then put in the dumpster, heading to the incineration center of Bessieres. “They will be treated in an energy recovery unit,” says Yoan Beaujon.
Wastewater, entering the Ginestous station, is subject to a daily analysis. They are also the new barometer for measuring the spread of Covid-19 as part of the Obépine network:
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Several treatment channels
The wastewater which passes through the screen continues its route into the treatment plant. “For the treatment, we have two channels organic and a sector physico-chemical », Describes Yoan Beaujon. The sludge thus formed is “injected into the methanization unit”.
After a passage in a last refining treatment line, the decontaminated water finishes its course in the Garonne. Of polystyrene beads capture the latest pollution.
–Become a resource factory
“Toulouse captures every year 50 million m3 in the Garonne, against 40 million m3 donated to the Garonne ”, points out Robert Médina, the elected representative of Toulouse Métropole. “We could reuse this treated water to capture less in the Garonne. The idea, ultimately, for Toulouse Métropole wateris that Ginestous becomes a resource factory ».
Other projects to come
In addition to the establishment of an anaerobic digestion plant, other projects are to come, as part of the odor reduction plan. “A deodorization system will be replaced,” says Yoan Beaujon. ” It’s about a stale air treatment unit, with the use of different reagents allowing to capture odorous compounds ”.
This odor reduction plan is “on a neighborhood scale”, emphasizes the manager of the Ginestous plant. “The wastewater treatment plant is not the only source of odor nuisance,” he emphasizes. They can also come from the green waste composting platform in the immediate vicinity.
–Composting in a closed place
Robert Médina sheds light on this subject: “The reduction of sludge, the result of the commissioning of anaerobic digestion, leads to close one of the sludge elimination treatment channels by Ginestous. The land could be recovered to accommodate the composting of green waste, today in the open ”. This waste will thus be stored in a closed place. This composting platform could close as early as April.
–Finally, some works will be covered. “The idea is to confine odors, to be able to process them, ”explains Yoan Beaujon, the manager of Ginestous. “An odor measurement platform will also be deployed. A battery of sensors and new deodorization systems are planned all around, to cover the Ginestous plant ”.
–A new sludge dryer
In addition to the plan to reduce bad odors, two other projects have been launched. A new biological treatment unit water, which will be inserted between two treatment lines, is planned. Objective: an optimization of the process.
The third project consists of the installation of a new sludge dryer “Which will compensate for the disappearance of the composting platform,” explains Yoan Beaujon. “Until now, the storage of the dryer pellets has been outside. It could be a source of odor in the neighborhood. The storage of the granules of the future dryer will be deodorized ventilated silos ».
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