- In operation since: 2009
- Designed by EPUR NATURE
- Type of wastewater treated: Domestic and stormwater
- Hydraulic load: 2000 m³/day
- Organic load (PE): 4000 PE
- Organic design load (kg BOD/day): 240 kg BOD/day
- Location: Sillé Le Guillaume
- Client: Town of Sillé Le Guillaume
- Stage 1 type: French system
- Stage 1 surface area (m²): 6000 m²
- Stage 2 type: Vertical flow, unsaturated
- Stage 2 surface area (m²): 4000 m²
The existing combined sewerage network of Sillé Le Guillaume catches large amounts of storm and drainage water, especially in winter, making the treatment with an activated sludge plant impossible without considerable investment into the sewer system. The receiving water body is a very small and fragile stream, offering little dilution in summer and being severely impacted even if discharged waste-water is well treated.
Two stage reed bed filters, for the dry weather flow, fed by by two pumping stations. There is no primary treatment, the raw, only manually coarse screened sewage is fed directly on the first stage beds. Excess water during storm events is directed from two overflows, at the inflow of the first and second stage of the reed bed filters, towards a huge settlement pond. Outflow of both settlement ponds and the second stage reed bed flow through a 6000 m² surface flow wetland for polishing before discharged into the small stream. During the summer months, the outflow of the surface flow wetland is entirely used for the irrigation of a bamboo plantation of 3 ha, thus resulting in a zero surface water discharge.
An unused land area has been transformed in an aesthetically pleasing wetland area with high habitat value, providing at the same time the best solution, in terms of efficiency, CAPEX and OPEX for the treatment of the waste - and storm water of the town of Sillé Le Guillaume. In summer, the treated water is used to produce bamboos, for which there is a market as raw material for construction and crafting, as well as renewable energy source.