Bilbao is the most important city in the north coast of Spain and one of the main industrial areas in the country. The combined sewer system of this city transports the wastewater to two treatment plants that include nutrient removal with a capacity over 8 m~3/sec. The maximum flow in the sewer system during big storms reaches 23 m~3/sec. Nowadays the effluents of these plants are discharged into a harbor surrounded by several beaches. Those discharges and the combined sewer overflows, causes the fecal contamination of bathing waters, so the construction of a submarine outfall has been selected as a solution to fulfill the required environmental quality objectives in this area. Thus the environmental design of this submarine outfall has considered the definition of the discharge area and the diffuser characteristics to obtain maximum efficiency in the use of natural processes to assimilate the treated waste water into the marine environment. The design has been developed using numerical models to simulate the hydrodynamics, dispersion and decay of the pollutants disposed into the sea. The study of the effects of the discharges on water quality has been extended to several years where the meteorological, hydrodynamic and physical characteristics of the zone were known.
展开▼
