A dynamic model of the clarification-thickening process

Takács, Imre

doi:10.1016/0043-1354(91)90066-y

Cited by 814 publications

(386 citation statements)

References 9 publications

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“…A minimum solids retention time (SRT, also referred as 'sludge age') of about 3 days is required for bacteria to aggregate into flocs (bio-flocculation) so as to enable their gravitational separation. (3) A sludge recycle line returning the major proportion of the settled sludge to the bioreactor, thus allowing Settler model ---Not specified Takács [31] Takács [31] Takács [31] Takács [31] Takács [31] Takács [31] Takács [31] Open-/Closed-loop problem Takács [31] Point-settler Takács [31] Takács [31] for the secondary settler. Point-settler for the primary settler…”

Section: Introductionmentioning

confidence: 99%

“…Takács [31] Takács [31] Not specified Takács [31] Open-/Closed-loop problem to maintain a high bacterial concentration in the reactor so as to intensify the biological nutrient removal. A first benefit of sludge recycling is decoupling the hydraulic retention time (HRT) and SRT: hence, an efficient treatment can be achieved for an HRT of the order of ten hours only.…”

Section: Introductionmentioning

confidence: 99%

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Optimal design and operation of activated sludge processes: State-of-the-art

Hreiz

Latifi

Roche

2015

Chemical Engineering Journal

171

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To cite this version:Rainier Hreiz, M A Latifi, Nicolas Roche. Optimal design and operation of activated sludge processes: State-of-the-art. Chemical Engineering Journal, Elsevier, 2015Elsevier, , 281, pp.900 -920. 10.1016Elsevier, /j.cej.2015 The paper deals with the optimal control and design of activated sludge processes. Studies on the topic are critically reviewed. Focus is set on the problem formulation that allows one getting reliable solutions. The selection of appropriate cost functions and constraints is discussed. Aspects related to dealing with model mismatch are presented. a r t i c l e i n f o t r a c tThe activated sludge process (ASP) is the most commonly used process for wastewater treatment. Improving its performance is necessary from economic and environmental point of views. In this context, dynamic optimization is a powerful tool for assisting engineers in determining optimal operations and designs for ASPs.However, the real optimality of the solution strongly depends on the optimization problem statement, for which unfortunately, there is no standard or commonly accepted formulation. In a hopeful attempt to provide a guideline for future works on the topic, this paper reviews the literature devoted to optimal control and design of ASPs. The main issues to be addressed in order to get reliable solutions are discussed, among which: (1) Managing the inevitable mismatch between the model predictions and the real ASP operation. (2) Dealing with the unpredictable variations in the wastewater characteristics. (3) Accounting for the slowest dynamic processes occurring in ASPs. (4) Appropriately selecting the decision variables and the flowsheet structure in order to simplify the problem formulation from a mathematical perspective. (5) Conveniently choosing the cost functions expressions/correlations. (6) Successfully selecting the mathematical constraints in order to guarantee physically relevant operations.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal design and operation of activated sludge processes: State-of-the-art

Hreiz

Latifi

Roche

2015

Chemical Engineering Journal

171

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“…According to Abusam and Keesman [12], r p is the most sensitive parameter of the secondary clarifier. Takacs et al [8] recommend finding the value of r p by simulation.…”

Section: Cod and Tn Fractionation Methodsmentioning

confidence: 99%

“…As recommended by the United States Environmental Protection Agency (US-EPA) [6], the equation proposed by Davis [7] was used to find out that 18 continuous stirred-tank reactor (CSTR) can reproduce the hydraulics of the aeration tanks. The secondary clarifier was modeled using the model developed by Takacs et al [8].…”

Section: A Model Developmentmentioning

confidence: 99%

Calibration of ASM1 for Carbon and Nitrogen Removals of Riqqa Activated Sludge System, Kuwait

Abusam¹

2014

IJMO

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Abstract-Riqqa plant, the second largest wastewater treatment plant in Kuwait, has lately shown signs of working under unstable conditions. The Kuwait Institute for Scientific Research has conducted a study to evaluate the plant performance and to pin-point the probable causes of the problem. To achieve these objectives, the Riqqa activated sludge system was modelled using activated sludge model No. 1 (ASM1) in SIMBA simulation package. It was the first time to use ASM1 to model a full-scale activated sludge system in Kuwait. This paper presents the calibration of ASM1 to carbon and nitrogen removals of the Riqqa activated sludge system, using long-term routinely measured wastewater quality parameters. Repirometery analysis was used to help in chemical oxygen demand (COD) fractionation and for providing initial guess values for the calibrated parameters. Validation results showed reasonable agreement between the measured and simulated COD, NH 4 -N and NO 3 -N over long-term dynamic simulation. The developed model was then used to evaluate and diagnose the system performance. The values of ASM1 parameters obtained will be useful in modelling other activated sludge systems in the country.

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“…The reactors are followed by a secondary settler that is modeled using the 10-layer model proposed by Takács et al (1991). The secondary settler is considered non-reactive and has a volume of 6000 m 3 with a horizontal cross-section of 1500 m 2 and a depth of 4 m.…”

Section: Figurementioning

confidence: 99%

Development and economic assessment of different WWTP control strategies for optimal simultaneous removal of carbon, nitrogen and phosphorus

Ostace

Baeza

Guerrero

et al. 2013

Computers & Chemical Engineering

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This paper presents the comparison of four control strategies for the A 2 /O WWTP configuration for simultaneous C, N and P removal. The control strategies: i) external COD-P control; ii) external recycle flow-P control; iii) nitrate control in the last anoxic reactor; iv) ammonia control in the last aerobic reactor, were combined with other common control loops to build different control structures and were simulated in Matlab/Simulink under different influent conditions. A systematic approach was conducted with all the strategies to assess their potential effectiveness, according to the following steps: theoretical design, setpoint optimization and, finally, a detailed comparison of the control results against a reference operation and an optimized reference scenario. The optimization of the reference operation presented a 7 % reduction of the total operational cost. The simulation results showed that some control strategies further reduced 3-7.5% the WWTP operational costs while the effluent quality is greatly improved.

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A dynamic model of the clarification-thickening process

Cited by 814 publications

References 9 publications

Optimal design and operation of activated sludge processes: State-of-the-art

Optimal design and operation of activated sludge processes: State-of-the-art

Calibration of ASM1 for Carbon and Nitrogen Removals of Riqqa Activated Sludge System, Kuwait

Development and economic assessment of different WWTP control strategies for optimal simultaneous removal of carbon, nitrogen and phosphorus

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