CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime

Sánchez, F.; Rey, H.; Viedma, A.; Nicolás-Pérez, F.; Kaiser, Antonio Sánchez; Martínez, María

doi:10.1016/j.watres.2018.03.067

Cited by 49 publications

(15 citation statements)

References 26 publications

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“…The ICEAS technology is an improved version of the sequencing batch reactor (SBR) technology, with continuously flowing influent, and it is fully automatic (Coelho et al, 2000;Fikar et al, 2005;Spagni and Marsili-Libelli, 2009). Due to its mode of operation and design, its advantages include: (i) reduced consumption of dissolved oxygen (DO), (ii) less energy requirement, i.e., 10-15% less energy for aeration compared to aeration-based biological processes (Liu and Wang, 2017;Sanchez et al, 2018), (iii) ability to tolerate shock loads of organics, (iv) reduced emission of greenhouse gas (~36%), and (v) high total nitrogen (TN) removal efficiency compared to the SBR technology (Spagni and Marsili-Libelli, 2009). Several previous research works have also reported on the removal of nutrients (nitrogen and phosphorus) from different wastewater sources using ICEAS.…”

Section: Introductionmentioning

confidence: 99%

Removal of Nutrients From Anaerobically Digested Swine Wastewater Using an Intermittent Cycle Extended Aeration System

2020

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Swine wastewater contains high concentrations of organic compounds, nutrients (nitrogen and phosphorus), heavy metals, and residual antibiotics, amongst others, that have negative impacts on the water environment. The main aim of this work was to remove nutrients from anaerobically digested swine wastewater using an intermittent cycle extended aeration system (ICEAS). The effects of operational parameters such as cycle time, organic loading rate, C/N ratio, and aeration/mixing ratio on the pollutant removal efficiencies of ICEAS were studied and compared with the performance of a conventional sequencing batch reactor (SBR). The following optimal conditions were obtained: cycle time, 6 h; organic loading rate, 0.86 kg COD m −3 day −1 ; C/N ratio, 2.49-2.82; and aeration/ mixing ratio, 1.57. The pH was maintained in the range of 6.0-8.0. The total organic carbon (TOC), total nitrogen (TN), ammonium (NH 4 +), total phosphorus (TP), and color removal efficiencies of ICEAS were higher than those of the conventional SBR, with removal

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Section: Introductionmentioning

confidence: 99%

Removal of Nutrients From Anaerobically Digested Swine Wastewater Using an Intermittent Cycle Extended Aeration System

2020

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“…The flows in the OD are by nature highly turbulent, and therefore, the most common, less intensive resource tool to model them is through the solution of the RANS equations [3,[26][27][28]. These equations apply the Reynolds decomposition in the velocity and pressure [29], as follows:…”

Section: Governing Equationsmentioning

confidence: 99%

Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

Zhang

et al. 2019

Water

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The oxidation ditch (OD) plays an important role in wastewater treatment plants. With increasing demand and production costs, the energy consumption and sludge deposition occurring in the OD must be diminished to enhance its development. In this paper, a two-phase computational fluid dynamics (CFD) model of water and activated sludge examined the flow field characteristics of an OD, consisting of two side-by-side propellers. The system was studied under five configurations, where the spacing between the propellers was set equal to −0.2, −0.1, 0, 0.1, 0.2 times the length of the OD. The viscosity and settling rate of activated sludge was imported in the numerical simulation through a user defined function (UDF). The optimal scheme of the propeller’s power consumption, velocity distribution, and sludge concentration distribution was obtained. The result shows that sludge concentrations are linked with dead zone velocity but not necessarily with low velocities. Experiments confirmed the validity of the velocity flow field simulated by the two-phase CFD model. Overall, these findings form the basis for the propellers distribution optimization and allow a deeper insight into the flow field of OD systems.

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“…In [11], the evolution of environmental performance indicators is considered in [11] to evaluate the impact of control strategies. In [13], a dynamic model of activated sludge reactors working under an intermittent aeration regime is developed to evaluate the link between aeration and effluent quality, the analysis of airflow rate influence on performance allow to increase process efficiency, producing a reduction of 14.5% on power consumption. The selection of a time horizon is equivalent to giving a weight to time and is one of the most critical parts of the carbon accounting processes [14,15].…”

Section: Introductionmentioning

confidence: 99%

Quantifying the Benefit of a Dynamic Performance Assessment of WWTP

et al. 2020

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In this work a comprehensive analysis of the environmental impact of the operation of a wastewater treatment plant (WWTP) using different control strategies is carried out considering the dynamic evolution of some environmental indicators and average operation costs. The selected strategies are PI (proportional integral) control schemes such as dissolved oxygen control in the aerobic zone (DO control), DO control and nitrates control in the anoxic zone (DO + NO control) and regulation of ammonium control at the end of aerobic zone (Cascade SNHSP) commonly used in WWTPs to maintain the conditions that ensure the desired effluent quality in a variable influent scenario. The main novelty of the work is the integration of potential insights into environmental impact from the analysis of dynamic evolution of environmental indicators at different time scales. The consideration of annual, bimonthly and weekly temporal windows to evaluate performance indicators makes it possible to capture seasonal effects of influent disturbances and control actions on environmental costs of wastewater treatment that are unnoticed in the annual-based performance evaluation. Then, in the case of periodic events, it is possible to find solutions to improve operation by the adjustment of the control variables in specific periods of time along the operation horizon. The analysis of the annual average and dynamic profiles (weekly and bimonthly) of environmental indicators showed that ammonium-based control (Cascade SNHSP) produce the best compromise solution between environmental and operation costs compared with DO control and DO + NO control. An alternative control strategy, named SNHSP var Qcarb var, has been defined considering a sequence of changes on ammonium set-point (SNHSP) and carbon dosage (Qcarb) on different temporal windows. It is compared with DO control considering weekly and bimonthly profiles and annual average values leading to the conclusion that both strategies, Cascade SNHSP and SNHSP var Qcarb var, produce an improvement of dynamic and annual average environmental performance and operation costs, but benefits of Cascade SNHSP strategy are associated with reduction of electricity consumption and emissions to water, while SNHSP var Qcarb var strategy reduces electricity consumption, use of chemicals (reducing external carbon dosage) and operation costs.

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CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime

Cited by 49 publications

References 26 publications

Removal of Nutrients From Anaerobically Digested Swine Wastewater Using an Intermittent Cycle Extended Aeration System

Removal of Nutrients From Anaerobically Digested Swine Wastewater Using an Intermittent Cycle Extended Aeration System

Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

Quantifying the Benefit of a Dynamic Performance Assessment of WWTP

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