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Diego Rosso - One of the best experts on this subject based on the ideXlab platform.
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dynamic impact of cellulose and readily biodegradable substrate on Oxygen Transfer Efficiency in sequencing batch reactors
Water Research, 2021Co-Authors: Ahmed Shawki Ahmed, Diego Rosso, Ahmed Khalil, Yuichi Ito, Mark C M Van Loosdrecht, Domenico Santoro, George NakhlaAbstract:Abstract Aeration is a major contributor to the high energy demand in municipal wastewater treatment plants. Thus, it is important to understand the dynamic impact of wastewater characteristics on Oxygen Transfer Efficiency to develop suitable control strategies for minimizing energy consumption since aeration Efficiency is influenced by the biodegradation of pollutants in the influent. The real-time impact of acetate as a readily biodegradable substrate and cellulose as a slowly biodegradable substrate were studied at different operational conditions. Cellulose in the influent wastewater can be removed efficiently using primary treatment technologies, such as the rotating belt filter (RBF). At an ambient DO of 2 mg l−1 and air flow of 1.02 m3 h−1 (0.6 SCFM), the α-factor was more sensitive to readily biodegradable substrates than to cellulose. On average, α-factor decreased by 48% and 19% due to the addition of acetate and cellulose, respectively. At a DO of 4 mg l−1 and air flow of 1.7 m3 h−1 (1 SCFM), α-factor remained constant irrespective of cellulose and acetate concentrations. Without active biomass, α-factor decreased by 47% and 43% at a DO of 2 mg l−1 (air flow of 1.02 m3 h−1) and high DO of 5 mg l−1 (air flow of 1.7 m3 h−1), respectively. An inverse correlation between α-factor and sCOD was defined and incorporated into a dynamic model to estimate the real-time airflow rates associated with the improvement of the Oxygen Transfer Efficiency due to biodegradation. Finally, the RBF operated with a 158-μm mesh selectively removed cellulose, thus reducing air requirements, and energy by 25%.
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increasing Oxygen Transfer Efficiency through sorption enhancing strategies
Water Research, 2020Co-Authors: Manel Garridobaserba, Victory Odize, Ahmed Alomari, Diego Rosso, Michael K. Stenstrom, Sudhir Murthy, John T. Novak, Arifur Rahman, Tim Van Winckel, Haydee De ClippeleirAbstract:Abstract The link between aeration Efficiency and biosorption capacity in water resource recovery facilities was extensively investigated, with special emphasis on wastewater characteristics and the development of strategies to maximize adsorption. Biosorption of Oxygen Transfer inhibitors (i.e., surfactants, colloidal, and soluble fractions) was examined by a series of pilot batch-scale experiments and full-scale studies. The impact of a sorption-enhancing strategy (i.e., bioaugmentation) deployed at full-scale over a five-year period was evaluated. Bench-scale experiments determined the inhibition coefficient (Ki) to measure the impact of surfactants and COD fractions as inhibitors of Oxygen Transfer efficiencies (αSOTE) in wastewater systems. The inhibition constant for surfactants Ki was found at 2.4 ± 0.4 mg L−1 SDS while for colloidal material was at 14 ± 1 mg L−1 (no inhibition for soluble fraction was found). Two enhancing biosorption configurations (i.e., contact stabilization and anaerobic selector) resulted in significant improvements in both aeration Efficiency indicators (αSOTE) and surfactants removals. αSOTE improvements of 46% and 54% in comparison to conventional high rate activated sludge process (HRAS) were reported. Similarly, the removal of surfactants was increased by 27% and 56% using optimized enhancing-sorption strategies. Further analyses helped elucidate the underlying mechanisms of surfactants removal. Findings are expected to help full-scale applications increase their sorption potential as well as the concurrent aeration Efficiency, which helps WRRFs to advance toward energy-positive wastewater treatments.
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reverse flexing as a physical mechanical treatment to mitigate fouling of fine bubble diffusers
Water Science and Technology, 2017Co-Authors: Victory Odize, Haydee De Clippeleir, Ahmed Alomari, Joshua D Smeraldi, Sudhir Murthy, John T. Novak, Diego RossoAbstract:Achieving energy neutrality has shifted focus towards aeration system optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. A study on fine bubble diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), Oxygen Transfer Efficiency and alpha was carried out in Blue Plains, Washington, DC. Four polyurethane fine bubble diffusers were installed in a pilot reactor column fed with high rate activated sludge from a full scale system. A mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2), while two diffusers were kept as a control (i.e., no reverse flexing). There was a 45% increase in DWP of the control diffuser after 17 months of operation, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show significant increase in DWP, and in comparison to the control diffuser prevented about 35% increase in DWP. Hence, reverse flexing potentially saves blower energy, by reducing the pressure burden on the air blower which increases blower energy requirement. However, no significant impact of the RF treatment in preventing a decrease in alpha-fouling ( α F) of the fine pore diffusers, over time in operation was observed.
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Oxygen Transfer and uptake nutrient removal and energy footprint of parallel full scale ifas and activated sludge processes
Water Research, 2011Co-Authors: Diego Rosso, Sarah Lothman, Matthew K Jeung, Paul Pitt, James W Gellner, Alan Stone, Don HowardAbstract:Abstract Integrated fixed-film activated sludge (IFAS) processes are becoming more popular for both secondary and sidestream treatment in wastewater facilities. These processes are a combination of biofilm reactors and activated sludge processes, achieved by introducing and retaining biofilm carrier media in activated sludge reactors. A full-scale train of three IFAS reactors equipped with AnoxKaldnes media and coarse-bubble aeration was tested using off-gas analysis. This was operated independently in parallel to an existing full-scale activated sludge process. Both processes achieved the same percent removal of COD and ammonia, despite the double Oxygen demand on the IFAS reactors. In order to prevent kinetic limitations associated with DO diffusional gradients through the IFAS biofilm, this systems was operated at an elevated dissolved Oxygen concentration, in line with the manufacturer’s recommendation. Also, to avoid media coalescence on the reactor surface and promote biofilm contact with the substrate, high mixing requirements are specified. Therefore, the air flux in the IFAS reactors was much higher than that of the parallel activated sludge reactors. However, the standardized Oxygen Transfer Efficiency in process water was almost same for both processes. In theory, when the Oxygen Transfer Efficiency is the same, the air used per unit load removed should be the same. However, due to the high DO and mixing requirements, the IFAS reactors were characterized by elevated air flux and air use per unit load treated. This directly reflected in the relative energy footprint for aeration, which in this case was much higher for the IFAS system than activated sludge.
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measuring Oxygen Transfer Efficiency ote at the eindhoven wwtp using real time off gas analysis in circular aeration tank
IWA BeNeLux Regional Young Water Professionals Conference 2nd Papers, 2011Co-Authors: Giacomo Bellandi, Diego Rosso, Salvatore Plano, Thomas Maere, Webbey De Keyser, Stefan Weijers, Tony Flameling, Ingmar NopensAbstract:Aeration Efficiency in the activated sludge basin of the Eindhoven wastewater treatment plant was monitored during two off-gas measurement campaigns using the ASCE method for Oxygen Transfer testing. Different locations were sampled and revealed differences in αSOTE values both in tangential as in radial direction. The highest values were found at the end of the aeration zone (ca. 38%), the lowest at the start (ca. 30%) and intermediate values in between. Differences in the radial direction were negligible at the start of the aeration zone, but became more significant towards the end. This hints that homogeneity in terms of OTE can be assumed at the start of the aeration zone, but does not longer hold at the end of the aeration zone.
Michael K. Stenstrom - One of the best experts on this subject based on the ideXlab platform.
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increasing Oxygen Transfer Efficiency through sorption enhancing strategies
Water Research, 2020Co-Authors: Manel Garridobaserba, Victory Odize, Ahmed Alomari, Diego Rosso, Michael K. Stenstrom, Sudhir Murthy, John T. Novak, Arifur Rahman, Tim Van Winckel, Haydee De ClippeleirAbstract:Abstract The link between aeration Efficiency and biosorption capacity in water resource recovery facilities was extensively investigated, with special emphasis on wastewater characteristics and the development of strategies to maximize adsorption. Biosorption of Oxygen Transfer inhibitors (i.e., surfactants, colloidal, and soluble fractions) was examined by a series of pilot batch-scale experiments and full-scale studies. The impact of a sorption-enhancing strategy (i.e., bioaugmentation) deployed at full-scale over a five-year period was evaluated. Bench-scale experiments determined the inhibition coefficient (Ki) to measure the impact of surfactants and COD fractions as inhibitors of Oxygen Transfer efficiencies (αSOTE) in wastewater systems. The inhibition constant for surfactants Ki was found at 2.4 ± 0.4 mg L−1 SDS while for colloidal material was at 14 ± 1 mg L−1 (no inhibition for soluble fraction was found). Two enhancing biosorption configurations (i.e., contact stabilization and anaerobic selector) resulted in significant improvements in both aeration Efficiency indicators (αSOTE) and surfactants removals. αSOTE improvements of 46% and 54% in comparison to conventional high rate activated sludge process (HRAS) were reported. Similarly, the removal of surfactants was increased by 27% and 56% using optimized enhancing-sorption strategies. Further analyses helped elucidate the underlying mechanisms of surfactants removal. Findings are expected to help full-scale applications increase their sorption potential as well as the concurrent aeration Efficiency, which helps WRRFs to advance toward energy-positive wastewater treatments.
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Real-Time Aeration Efficiency Monitoring in the Activated Sludge Process and Methods to Reduce Energy Consumption and Operating Costs
Water Environment Research, 2009Co-Authors: Shao-yuan Leu, Lory E Larson, Diego Rosso, Michael K. StenstromAbstract:Aeration is the most energy intensive unit operation in municipal wastewater treatment, and fine-pore diffusers have been widely used to minimize power consumption. Unfortunately, fine-pore diffusers suffer from fouling and scaling problems, which cause a rapid decline in aeration performance and significant increase in power consumption. Diffusers must be cleaned periodically to reduce energy costs. The cleaning frequency of diffusers is site-specific and its effectiveness can be evaluated with Oxygen Transfer Efficiency (OTE) testing. Off-gas testing is the best technique for measuring OTE in real-time. Fine-pore diffusers have low a factors that are further reduced at high loading rate. A time-series of off-gas measurements were conducted to demonstrate the value of real-time OTE data for developing energy-conserving operating strategies. The observations confirm the inverse correlation between OTE and airflow rate as well as the economic benefits of diffuser cleaning. In addition, mathematic models were applied to simulate the transient Oxygen uptake rate (OUR) and show the impact of varying load on OTE and aeration cost, especially when faced with time-of-day power rates. Regular diffuser cleaning can reduce average power costs by 18% and various equalization alternatives can reduce power costs by 6 to 16%.
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membrane properties change in fine pore aeration diffusers full scale variations of Transfer Efficiency and headloss
Water Research, 2008Co-Authors: Diego Rosso, J A Libra, Wolfgang Wiehe, Michael K. StenstromAbstract:Fine-pore diffusers are the most common aeration system in municipal wastewater treatment. Punched polymeric membranes are often used in fine-pore aeration due to their advantageous initial performance. These membranes are subject to fouling and scaling, resulting in increased headloss and reduced Oxygen Transfer Efficiency, both contributing to increased plant energy costs. This paper describes and discusses the change in material properties for polymeric fine-pore diffusers, comparing new and used membranes. Three different diffuser technologies were tested and sample diffusers from two wastewater treatment facilities were analysed. The polymeric membranes analysed in this paper were composed of ethylene-propylene-diene monomer (EPDM), polyurethane, and silicon. Transfer Efficiency is usually lower with longer times in operation, as older, dilated orifices produce larger bubbles, which are unfavourable to mass Transfer. At the same time, headloss increases with time in operation, since membranes increase in rigidity and hardness, and fouling and scaling phenomena occur at the orifice opening. Change in polymer properties and laboratory test results correlate with the decrease in Oxygen Transfer Efficiency.
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aeration of large scale municipal wastewater treatment plants state of the art
Water Science and Technology, 2008Co-Authors: Lory E Larson, Diego Rosso, Michael K. StenstromAbstract:Aeration is the most energy-intensive operation in wastewater treatment, amounting to 45-75% of plant energy costs. Fine-pore diffusers are today almost ubiquitous in municipal wastewater aeration, due to their advantageous aeration Efficiency (mass of Oxygen Transferred per unit energy required). Nevertheless, older municipal treatment facilities and many industrial treatment plants are still equipped with coarse-bubble or surface aerators. Fine-pore diffusers are subject to two major disadvantages: a) fouling, if not cleaned periodically; b) decrease in Oxygen Transfer Efficiency caused by dissolved surfactants. Coarse-bubble and surface aerators are typically not subject to the traditional problems affecting fine-pore diffusers. Nonetheless, they achieve Oxygen Transfer at the expense of increased energy intensity. The increased biomass concentration associated with high mean cell retention time (MCRT) operations has a beneficial effect on aeration. Nutrient-removing selectors are able to further increase aeration Efficiency, as they sorb and utilize the readily available substrate which otherwise would accumulate at bubble surfaces and dramatically decrease aeration Efficiency. We summarise here our 30-year long experience in aeration research, and results obtained with clean- and process-water tests are used to show the beneficial effects of high MCRT operations, the beneficial effect of selectors, and the decline of aeration Efficiency due to dissolved surfactants.
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comparative economic analysis of the impacts of mean cell retention time and denitrification on aeration systems
Water Research, 2005Co-Authors: Diego Rosso, Michael K. StenstromAbstract:Biological nutrient removal is practiced in various modifications of the activated sludge process (ASP) throughout the world. This paper compares conventional, nitrifying-only and combined nitrifying/denitrifying (NDN) processes. The authors performed 113 Oxygen Transfer Efficiency measurements with the off-gas method over 20 years. This dataset was analysed and used to perform an economic analysis for three example scenarios, one for each layout (conventional, nitrifying-only and NDN). Field Oxygen Transfer Efficiency and relevant plant operative costs and credits were considered (i.e., aeration cost, sludge disposal cost, methane production credit). The conclusion is that NDN operations always have lower aeration costs, and generally have the lowest combined operating cost. Reduced aeration costs result because of improved aeration Efficiency at higher mean cell retention times and the use of nitrate as an electron acceptor. The improved aeration Efficiency overcomes the increased Oxygen required at higher cell retention time due to cell decay.
J M Poyatos - One of the best experts on this subject based on the ideXlab platform.
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influence of mixed liquid suspended solids and hydraulic retention time on Oxygen Transfer Efficiency and viscosity in a submerged membrane bioreactor using pure Oxygen to supply aerobic conditions
Biochemical Engineering Journal, 2012Co-Authors: F A Rodriguez, Patricia Reboleirorivas, E Hontoria, Francisco Osorio, M V Martineztoledo, J M PoyatosAbstract:Abstract The performance of a wastewater bench-scale membrane bioreactor (MBR) treatment plant using pure Oxygen conditions was monitored daily to provide aerobic conditions. The results showed the capacity of the MBR system to remove organic material over at hydraulic retention time (HRT) of 12 h and 18 h. The alpha-factors of aeration were determined at three different mixed liquid suspended solids (MLSS) concentrations, in order to understand the system performance when pure Oxygen was used to provide the aerobic conditions of the MBR system. Under these working conditions, an alpha-factor in the range 0.90–0.12 was obtained when the HRT of 18 h was performed, and the MLSS concentration increased from 4300 to 10,275 mg/L. Additionally, an alpha-factor in the range of 0.28–0.02 was obtained at HRT of 12 h and the MLSS increased from 4071 to 11,192 mg/L. Our study suggested significant changes in the behaviour of the biological system (viscosity, aeration Efficiency, organic matter removal) when the concentration of MLSS was increased and the HRT decreased in the bioreactor, decreasing the aeration Efficiency in both cases. Furthermore, the Efficiency of aeration seems to be more affected by MLSS concentration than by HRT under our operating conditions over the range studied.
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kinetic study and Oxygen Transfer Efficiency evaluation using respirometric methods in a submerged membrane bioreactor using pure Oxygen to supply the aerobic conditions
Bioresource Technology, 2011Co-Authors: F A Rodriguez, Patricia Reboleirorivas, J M Poyatos, Francisco Osorio, J Gonzalezlopez, E HontoriaAbstract:Abstract The performance of a wastewater bench-scale ultrafiltration membrane bioreactor (MBR) treatment plant using pure Oxygen to supply the aerobic conditions for 95 days was studied. The results showed the capacity of the MBR systems to remove organic material under a hydraulic retention time of 12 h and a sludge retention time of 39.91 days. Aeration represents its major power input; this is why the alpha-factor of the aeration and kinetic parameters (design parameters) were determined when the mixed liquid suspended solids (MLSS) was increased from 3420 to 12,600 mg/l in order to understand the system. An alpha-factor in the range 0.462–0.022 and the kinetic parameters measured with the respirometric method ( K M of 73.954–3.647 mg/l, k d of 0.0142–0.104 day −1 , k H of 0.1266–0.655 day −1 , and the yield mean coefficient of 0.941) were obtained. Our study suggested significant changes in the behaviour of the biological system when the concentration of MLSS was increased.
E Hontoria - One of the best experts on this subject based on the ideXlab platform.
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influence of mixed liquid suspended solids and hydraulic retention time on Oxygen Transfer Efficiency and viscosity in a submerged membrane bioreactor using pure Oxygen to supply aerobic conditions
Biochemical Engineering Journal, 2012Co-Authors: F A Rodriguez, Patricia Reboleirorivas, E Hontoria, Francisco Osorio, M V Martineztoledo, J M PoyatosAbstract:Abstract The performance of a wastewater bench-scale membrane bioreactor (MBR) treatment plant using pure Oxygen conditions was monitored daily to provide aerobic conditions. The results showed the capacity of the MBR system to remove organic material over at hydraulic retention time (HRT) of 12 h and 18 h. The alpha-factors of aeration were determined at three different mixed liquid suspended solids (MLSS) concentrations, in order to understand the system performance when pure Oxygen was used to provide the aerobic conditions of the MBR system. Under these working conditions, an alpha-factor in the range 0.90–0.12 was obtained when the HRT of 18 h was performed, and the MLSS concentration increased from 4300 to 10,275 mg/L. Additionally, an alpha-factor in the range of 0.28–0.02 was obtained at HRT of 12 h and the MLSS increased from 4071 to 11,192 mg/L. Our study suggested significant changes in the behaviour of the biological system (viscosity, aeration Efficiency, organic matter removal) when the concentration of MLSS was increased and the HRT decreased in the bioreactor, decreasing the aeration Efficiency in both cases. Furthermore, the Efficiency of aeration seems to be more affected by MLSS concentration than by HRT under our operating conditions over the range studied.
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kinetic study and Oxygen Transfer Efficiency evaluation using respirometric methods in a submerged membrane bioreactor using pure Oxygen to supply the aerobic conditions
Bioresource Technology, 2011Co-Authors: F A Rodriguez, Patricia Reboleirorivas, J M Poyatos, Francisco Osorio, J Gonzalezlopez, E HontoriaAbstract:Abstract The performance of a wastewater bench-scale ultrafiltration membrane bioreactor (MBR) treatment plant using pure Oxygen to supply the aerobic conditions for 95 days was studied. The results showed the capacity of the MBR systems to remove organic material under a hydraulic retention time of 12 h and a sludge retention time of 39.91 days. Aeration represents its major power input; this is why the alpha-factor of the aeration and kinetic parameters (design parameters) were determined when the mixed liquid suspended solids (MLSS) was increased from 3420 to 12,600 mg/l in order to understand the system. An alpha-factor in the range 0.462–0.022 and the kinetic parameters measured with the respirometric method ( K M of 73.954–3.647 mg/l, k d of 0.0142–0.104 day −1 , k H of 0.1266–0.655 day −1 , and the yield mean coefficient of 0.941) were obtained. Our study suggested significant changes in the behaviour of the biological system when the concentration of MLSS was increased.
F A Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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influence of mixed liquid suspended solids and hydraulic retention time on Oxygen Transfer Efficiency and viscosity in a submerged membrane bioreactor using pure Oxygen to supply aerobic conditions
Biochemical Engineering Journal, 2012Co-Authors: F A Rodriguez, Patricia Reboleirorivas, E Hontoria, Francisco Osorio, M V Martineztoledo, J M PoyatosAbstract:Abstract The performance of a wastewater bench-scale membrane bioreactor (MBR) treatment plant using pure Oxygen conditions was monitored daily to provide aerobic conditions. The results showed the capacity of the MBR system to remove organic material over at hydraulic retention time (HRT) of 12 h and 18 h. The alpha-factors of aeration were determined at three different mixed liquid suspended solids (MLSS) concentrations, in order to understand the system performance when pure Oxygen was used to provide the aerobic conditions of the MBR system. Under these working conditions, an alpha-factor in the range 0.90–0.12 was obtained when the HRT of 18 h was performed, and the MLSS concentration increased from 4300 to 10,275 mg/L. Additionally, an alpha-factor in the range of 0.28–0.02 was obtained at HRT of 12 h and the MLSS increased from 4071 to 11,192 mg/L. Our study suggested significant changes in the behaviour of the biological system (viscosity, aeration Efficiency, organic matter removal) when the concentration of MLSS was increased and the HRT decreased in the bioreactor, decreasing the aeration Efficiency in both cases. Furthermore, the Efficiency of aeration seems to be more affected by MLSS concentration than by HRT under our operating conditions over the range studied.
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kinetic study and Oxygen Transfer Efficiency evaluation using respirometric methods in a submerged membrane bioreactor using pure Oxygen to supply the aerobic conditions
Bioresource Technology, 2011Co-Authors: F A Rodriguez, Patricia Reboleirorivas, J M Poyatos, Francisco Osorio, J Gonzalezlopez, E HontoriaAbstract:Abstract The performance of a wastewater bench-scale ultrafiltration membrane bioreactor (MBR) treatment plant using pure Oxygen to supply the aerobic conditions for 95 days was studied. The results showed the capacity of the MBR systems to remove organic material under a hydraulic retention time of 12 h and a sludge retention time of 39.91 days. Aeration represents its major power input; this is why the alpha-factor of the aeration and kinetic parameters (design parameters) were determined when the mixed liquid suspended solids (MLSS) was increased from 3420 to 12,600 mg/l in order to understand the system. An alpha-factor in the range 0.462–0.022 and the kinetic parameters measured with the respirometric method ( K M of 73.954–3.647 mg/l, k d of 0.0142–0.104 day −1 , k H of 0.1266–0.655 day −1 , and the yield mean coefficient of 0.941) were obtained. Our study suggested significant changes in the behaviour of the biological system when the concentration of MLSS was increased.
