Dewatering sludge - France - Case Study
Sewage treatment plants
Châtres - FRANCE (77)
This plant uses a biological treatment process, “extended aeration activated sludge”, followed by a water clarifier. Up until May 2018, the sludge was treated using a dozen or so drying beds, which involved a number of manual operations.
The local authorities decided to use a sludge dewatering system with dewatering tubes. This method optimises the treatment surface and eliminates the tedious operations required to operate the drying beds during the winter months.
This solution also means that the sludge treated in the TenCateGéotube® can be stored before final disposal in a composting plant.
However, with this type of treatment, the sludge needs to be flocculated before being transferred to the TenCateGéotube®. Without good flocculation, the sludge cannot be filtered properly and the geo-membrane can become blocked.
Approach used / Answer given
The Châtres Town Council commissioned GEB Conseil to provide it with an integrated solution, including:
- A flocculating agent mixing cabinet, with integrated pumping, dilution, and treatment flow rate control,
- Treatability tests and an option to select the mixture to be used,
- Set-up and start-up on site,
- Training for council workers.
GEB Conseil, together with the local authorities, opted for the Dosatron D25WL2IEPO dosing pump.
They chose a polymer dosing pump that mixes the polymer with the water to obtain a homogenous solution before being injected into the sludge transfer pipe towards the TenCateGéotube®.
This technique optimises the treatment capacity of the old drying beds (10 to 15 times greater capacity), without any major work. The filtered water is collected using the existing drying bed drainage system.