Castelo Branco Wastewater Treatment Plant
The work required the execution of reinforced concrete structures with high quality requirements regarding watertightness and durability, as the surfaces and equipment are now in permanent contact with effluent. These requirements, applicable to all structures, demanded a careful selection process of materials and construction methods, considering the physical and chemical characteristics of the effluent.
Among the most relevant structures, the following reinforced concrete structures stand out: 2 circular settling tanks with a radius of 16 metres and a capacity of 2,600 m³, the aeration tank with dimensions of 35m x 63m x 7m and a capacity of 14,500 m³, and the 2 digesters with a capacity of 1,350 m³.
The new WWTP was built to replace the two existing units in Castelo Branco and was designed to treat domestic and industrial effluent for:
- Population equivalent to 95,000 inhabitants (PE)
- Average flow in dry weather: 12,496 m³/day
- Average flow in wet weather: 21,082 m³/day
- Peak flow in dry weather: 952 m³/h
- Peak flow in wet weather: 1,314 m³/h
- Capacity to treat pollutant load containing the following composition:
.BOD5 5,734 Kg/day
.COD 11,699 Kg/day
.TSS 5,444 Kg/day
.Total Nitrogen: 873 Kg/day
.Total Phosphorus: 114 Kg/day
The infrastructure also includes a pre-treatment building dedicated to the process of lifting, harrowing and removing sand, oils and grease from the effluent.
Primary treatment was carried out in 2 settling tanks equipped with bottom and surface scrapers. Secondary treatment was performed in the aeration tanks/oxidation ditches. After treatment of the liquid effluent, the WWTP includes a set of structures for sludge treatment, biogas production in 2 anaerobic digesters, and subsequent energy production through cogeneration.
