SOMAGUE Engenharia, S.A.
The detailed design involved the Alverca wastewater treatment plant, designed to serve a population equivalent of 188,000 inhabitants (average flow rate of 47,000 m³/day). The WWTP includes the following specific processes:
• Liquid phase (main line):
- Receiving and pretreating septic tank effluents; Pre-treatment (screening, stormscreen and desanding / degreasing, with aerobic biological treatment of fats); Primary decantation in lamellar settling tanks; Equalisation-homogenisation in two tanks and intermediate pumping; Secondary treatment in two aeration tanks; Secondary decantation in four circular settling tanks; Final disinfection by ultraviolet (UV) radiation.
• Liquid phase (rainwater line):
- Desanding; Physical-chemical treatment.
• Solid Phase:
- Thickening in gravity thickener; Thick sludge storage; Mechanical dewatering in centrifuges; Addition of lime.
- Ventilation system (extraction of gases) in the entrance and sludge treatment; Chemical deodorisation.
The project also includes a land outfall about 600 m long, in HDPE, DN 1 600.
Services provided in terms of design included: Preliminary design, field survey, detailed design, tender programmes and specifications. Services provided involved several fields of expertise such as: Sanitary engineering, hydraulics, structures, mechanics, electrical and electromechanical equipment, geotechnics, measurements and budgets.