Economic and efficient

Economic

The total investment cost is in the range of 2 M€ including implementation, studies, field acquisitions... i.e. less than an intensive unit of the same capacity.
Running costs will also be less.

Performances

The septage plant discharges in the natural river system very little water (5000 m³/year maximum) lightly polluted (BDO5 < 25 mg/l; COD < 125 mg/l; SS < 150 mg/l). It produces sludge used for agricultural fertilization and wood used for heating purposes.

Sludge is extracted from the filters (one filter per year normally) and spread on farmlands in place of industrial fertilisers.
The spreading on plantation, operated as Short Rotation Coppice-SRC, produce an average of 10 Dry Tonnes per acre or 50 DT/ year for the whole plantation.

The wood production increase resulting from the irrigation with wastewater (through water, nitrogen and phosphorus contributions) is not known as yet. Il will be measured in Nègrepelisse as part of the project experimental program.