Kinetic Study and Performance Evaluation of an Integrated Two-Phase Fixed-Film Baffled Bioreactor for Bioenergy Recovery From Wastewater and Bio-Wasted Sludge Publisher



Ahmadi E^{1, 2} ; Yousefzadeh S^{3, 4} ; Mokammel A⁵ ; Miri M⁶ ; Ansari M^{7, 8} ; Arfaeinia H^{9, 10} ; Badi MY¹¹ ; Ghaffari HR¹² ; Rezaei S¹³ ; Mahvi AH^{2, 4, 14}
Source: Renewable and Sustainable Energy Reviews Published:2020

Abstract

The present study evaluated the performance of an integrated two-phase fixed-film baffled bioreactor for wastewater treatment with regard to its energy consumption and production. The total potential of the bioenergy recovery of the bioreactor was evaluated not only from the anaerobic wastewater treatment but also from the produced bio-wasted sludge of both phases. Statistical correlations between bio-methane production and kinetic coefficients were uncovered. Methane yields between 0.15 and 0.30 L CH4.g sCODremoved−1 were obtained during anaerobic wastewater treatment. The maximum energy recoveries from the digestion of bio-wasted sludge (sloughed biofilm) equaled 0.28 and 0.3 L CH4. g TS−1 for aerobic and anaerobic units, respectively. The Grau model was appropriate for predicting the performance of the bioreactor and the potential of bio-methane production. It was demonstrated that substrate utilization rate (Rsu) and Grau coefficient (KG) can be applied to predict the rate of methane production. Regarding the volume of treated wastewater, the energy production was in the range of 2.8–12 kWh.m−3. Moreover, the overall energy consumption of wastewater treatment was in the range of 0.32–0.79 kWh/kg sCODremoved, while the total energy production was 3.7–5.1 kWh/kg sCODremoved. Therefore, the designed bioreactor was energy positive with net energy production of 3.39–4.5 kWh/kg sCODremoved−1. The total energy requirement for both wastewater treatment and bio-wasted sludge digestion was 7–15.5% of the total energy production, and, therefore, the bioreactor is a sustainable energy process. The contribution of anaerobic wastewater treatment and anaerobic digestion of bio-wasted sludge of aerobic and anaerobic units for energy recovery as bio-methane was 53, 26, and 21%, respectively. As the bioreactor achieved more than 95% of sCOD removal and have a high bioenergy production, and since kinetic coefficients demonstrated the considerably high performance of the bioreactor, it can be of interest as an appropriate treatment process. © 2019 Elsevier Ltd