A pilot-scale biotrickling filter (BTF) was operated in counter-current flow mode under anoxic conditions, using diluted agricultural digestate as inoculum and as the recirculation medium for the ...nutrient source. The process was tested on-site at an agricultural fermentation plant, where real biogas was used. The pilot plant was therefore exposed to real process-related fluctuations. The purpose of this research was to attest the validity of the filtration process for use at an industrial-scale by operating the pilot plant under realistic conditions. Neither the use of agricultural digestate as trickling liquid and nor a BTF of this scale have previously been reported in the literature. The pilot plant was operated for 149 days. The highest inlet load was 8.5 gS-H
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with a corresponding removal efficiency of 99.2%. The pH remained between 7.5 and 4.6 without any regulation throughout the complete experimental phase. The analysis of the microbial community showed that both anaerobic and anoxic bacteria can adapt to the fluctuating operating conditions and coexist simultaneously, thus contributing to the robustness of the process. The operation of an anoxic BTF with agricultural digestate as the trickling liquid proved to be viable for industrial-scale use.
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•A submergible 255 L prototype MFC module was operated under practical conditions.•The biggest ever-investigated scale multi-panel SS/AC cathodes were utilized.•Initially, good ...electrochemical performance and nutrient removal was achieved.•Severe inorganic fouling decreased power density about 91 % within 77 days.•Mechanical cleaning did not restore performance.
A submergible 255 L prototype MFC module was operated under practical conditions with municipal wastewater having a large share in industrial discharges for 98 days to investigate the performance of two of the largest, ever investigated multi-panel stainless steel/activated carbon air cathodes (85 × 85 cm). At a flow rate of 144 L/d, power density of 78 mW/m2Cat (317 mW/m3) and COD, TSS and TN removal of 41 ± 16 %, 36 ± 16 % and 18 ± 14 %, respectively, were reached. Observed Coulombic efficiency and substrate-specific energy recovery were 29.5 ± 14 % and 0.184 ± 0.125 kWhel/kgCOD,deg, respectively. High salt content of wastewater (TDS = 2.8 g/L) led to severe inorganic fouling causing a drastic decline in power output and energy recovery of more than 90 % in the course of experiments. Mechanical cleaning of the cathodes restored only 22 % (17 mW/m2Cat) of the power output and did not improve nutrient removal or energy recovery.
In this study, a 1000 L pilot scale internal loop airlift bioreactor was operated and compared to a mathematical model to determine the best design for optimal supply of oxygen for nitrification and ...sufficient air for biomass fluidization. The design model is based on parameters such as geometry, carrier density, and airflow of the 1000 L pilot scale bioreactor. The model predicts a range of superficial air velocities (0.009–0.013 m/s) under which the airlift bioreactor was fluidized. Three superficial air velocities (0.009 m/s, 0.011 m/s and 0.013 m/s) were experimentally tested in the pilot plant and the obtained circulation velocities were compared with the predicted design scenarios. The predicted velocity was in agreement with the measured velocity. The aim of the mathematical model and the calculations of different geometry scenarios was to define the optimal geometry design for the physical model. The results show that the ratio of the cross-sectional area between the riser and the downcomer of 1.33 resulted in the lowest superficial liquid velocity of 0.076 m/s in the riser at a relative low superficial air velocity of 0.011 m/s and a carrier density of 1030 kg/m3. This bioreactor design enabled longest retention time of particles in the oxygenated riser.
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•Low growth rate and competing heterotrophs continue to challenge nitrification.•Low liquid velocity and higher carrier fraction in riser enhance nitrification.•A three phase ...mathematical model was applied for predicting low liquid velocity.•Geometry, aeration, and carrier characteristics were major design criteria.•Construction of a 1000L pilot plant verified the design and liquid velocity.
In this study, a 1000L pilot scale internal loop airlift bioreactor was operated and compared to a mathematical model to determine the best design for optimal supply of oxygen for nitrification and sufficient air for biomass fluidization. The design model is based on parameters such as geometry, carrier density, and airflow of the 1000L pilot scale bioreactor. The model predicts a range of superficial air velocities (0.009–0.013m/s) under which the airlift bioreactor was fluidized. Three superficial air velocities (0.009m/s, 0.011m/s and 0.013m/s) were experimentally tested in the pilot plant and the obtained circulation velocities were compared with the predicted design scenarios. The predicted velocity was in agreement with the measured velocity. The aim of the mathematical model and the calculations of different geometry scenarios was to define the optimal geometry design for the physical model. The results show that the ratio of the cross-sectional area between the riser and the downcomer of 1.33 resulted in the lowest superficial liquid velocity of 0.076m/s in the riser at a relative low superficial air velocity of 0.011m/s and a carrier density of 1030kg/m3. This bioreactor design enabled longest retention time of particles in the oxygenated riser.
