TECHNICAL OVERVIEW
Water inflow and outflow in each basin is carried out using raised apertures at each end of the basin and controlled by sluice gates and motor-powered spillways. Water is collected in a gutter shared by all basins and distributed by two pipes to the distribution chambers in the decanters. Eight decanters collect clarified water and a culvert collects muddy water. Decanters are equipped with a rotating metal bridge from which scrapers are suspended. A chlorination building (30 by 22 m) injects gaseous chlorine to disinfect water in clarified effluent flowing in an underground basin prior to discharge into the pond. The pond, which has a capacity of 210,000 m³, consists of backfilled embankments 5 metres high and is covered with polyethylene membranes. Once it is treated, the wastewater can be used for irrigation. Excess water can be discharged into the stream without danger.
Four layers, with a diameter of 18 metres, receive muddy water, treat it, and return it to the pumping station; the water at the bottom is suctioned by 5 sludge pumps and discharged onto 20 drying beds. These drying beds (basins measuring 27 by 555 m) collect water from the sludge-percolation process. After drying in the sun, the sludge above the draining layers are recovered and stored.
The pipes running between facilities are all located underground. These are cast-iron pipes with polyethylene sheathing. Project planning helped ensure that most of the required tasks could be carried out internally, thereby minimising external participation.
