Comparison of control strategies for nitrogen removal in an activated sludge process in terms of operating costs: A simulation study

Stare, A.; Vrečko, Darko; Hvala, Nadja; Strmĉnik, Stanko

doi:10.1016/j.watres.2007.01.029

Cited by 167 publications

(89 citation statements)

References 7 publications

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“…: these two formula are the most commonly used in literature). Stare and coworkers [68] and Alasino and coworkers [38,39] expressed the aerator power consumption as a quadratic function of (k L a Â V L ): such a formulation combines the merits of both expressions used in [45,46].…”

Section: Aerators Power Consumptionmentioning

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

168

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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: Aerators Power Consumptionmentioning

confidence: 99%

“…Sludge may be stabilized by anaerobic or aerobic digestion, and/or by chemical or thermal sterilization. Sludge treatment charges reported in the literature vary from about 0.2 € kg À1 of dry sludge [38,54,60] to around 0.5 € kg À1 [36,45,46,68].…”

Section: Sludge Disposal/valorizationmentioning

confidence: 99%

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

Hreiz

Latifi

Roche

2015

Chemical Engineering Journal

168

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“…A lower cost when the pollutant is below the discharge limit and a higher cost when this limit is exceeded. Hence, the effluent pollutant concentrations are The total nitrogen and ammonia parameter values used in this research were obtained from Stare et al (2007). The total phosphorus parameters were assumed to be three times higher than the ammonium parameters.…”

Section: Performance Assessmentmentioning

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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“…In order to solve the main problems of wastewater management, researchers' efforts have been focused, during the last few years, on objectives, such as (i) improving the water quality by also minimizing the operational costs in order to achieve sustainable treatments and (ii) minimizing the sludge production and increasing its usability for energy recovery [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Joint Environmental and Economical Analysis of Wastewater Treatment Plants Control Strategies: A Benchmark Scenario Analysis

2016

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Abstract:In this paper, a joint environmental and economic analysis of different Wastewater Treatment Plant (WWTP) control strategies is carried out. The assessment is based on the application of the Life Cycle Assessment (LCA) as a method to evaluate the environmental impact and the Benchmark Simulation Model No. 1 (BSM1). The BSM1 is taken as the benchmark scenario used to implement the control strategies. The Effluent Quality Index (EQI) and the Overall Cost Index (OCI) are two indicators provided by BSM1 and used to evaluate the plant's performance from the effluent quality and the economic points of view, respectively. This work conducts a combined analysis and assessment of ten different control strategies defined to operate a wastewater treatment plant. This analysis includes the usual economic and performance indexes provided by BSM1 joined with the LCA analysis that determines the environmental impact linked to each one of the considered control strategies. It is shown how to get an overall evaluation of the environmental effects by using a normalized graphical representation that can be easily used to compare control strategies from the environmental impact point of view. The use of only the BSM1 indexes provides an assessment that leads to a clustering of control strategies according to the cost/quality tradeoff they show. Therefore, regarding the cost/quality tradeoff, all strategies in the same group are almost equal and do not provide an indication on how to proceed in order to select the appropriate one. It is therefore shown how the fact of adding a new, complementary, evaluation (LCA based) allows either to reinforce a decision that could be taken solely on the basis of the EQI/OCI tradeoff or to select one control strategy among the others.

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Comparison of control strategies for nitrogen removal in an activated sludge process in terms of operating costs: A simulation study

Cited by 167 publications

References 7 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

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

Joint Environmental and Economical Analysis of Wastewater Treatment Plants Control Strategies: A Benchmark Scenario Analysis

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