Author(s): Maria Concetta Tomei; Valentina Stazi; Marco Manetti And Domenica Mosca Angelucci
Linked Author(s): Maria Concetta Tomei
Keywords: Treated water reuse Energy recovery Anaerobic treatment Granular UASB
Abstract: Two laboratory-scale sequencing granular up-flow anaerobic sludge blanket (UASB) reactors operated in sequential and continuous mode have been tested for the treatment of urban wastewater at different operating conditions. In the sequential system, experiments were performed at different hydraulic retention times (HRTs in the range of 9-22 h) and temperatures of 15and 25 °C while the continuous bioreactor has been operated at HRT 9 h and T=15 °C and up-flow velocity in the range of 3-5 m/h. At all tested conditions and in both configurations, high quality effluent was achieved in terms of total solids (TS) concentration, while nitrogen and phosphorus were fully recovered in the effluent. At 25 °C the sequential bioreactor shows very good performance for COD removal (≥ 88%) without substantial differences for the tested HRTs. Higher HRTs are instead required at 15°C to reach comparable COD removals. In the continuous bioreactor removal efficiencies of ~ 90% have been detected even in the most severe conditions, i. e. HRT 9 h and T 15°C. Increase of the up-flow velocity positively affect the biogas production even if, in both cases, a high fraction of the produced CH4 remains dissolved in the liquid phase. This results highlights the need of investigate effective strategies aimed to remove or recover such energetic greenhouse gas in order to ensure optimal energy recovery and avoid losses of CH4 into the environment.
Year: 2025