Substrate Concentration

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform

A. Stathaki - One of the best experts on this subject based on the ideXlab platform.

  • Metaheuristic control of Substrate Concentration for an activated sludge process
    International Journal of Modelling Identification and Control, 2010
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, M.p. Tzamtzi, A. Stathaki
    Abstract:

    In this paper, a two-stage linear dynamic control scheme, using a metaheuristic approach, will be developed to control the effluent Substrate Concentration of an ASP. In the first stage, a static output feedback controller will be designed, using only measurements of the oxygen Concentration. In the second stage, an asymptotic non-linear estimator of the Substrate Concentration will be used and the estimate will be fed back through a PI controller. In particular, the model of the ASP will be presented both in its non-linear and linearised form. Based on the linearised approximation, a static inner loop controller will be designed using a metaheuristic search algorithm for the computation of the controller parameters. Following, an outer PI controller will be designed based on the linearised model, again using a metaheuristic search algorithm in order to compensate the influence of the non-linearities when the static controller is applied to the non-linear model. The performance of the overall closed loop system will be illustrated through simulation experiments.

  • Two-stage robust control of Substrate Concentration for an activated sludge process.
    ISA transactions, 2008
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, Robert E. King, A. Stathaki
    Abstract:

    A two-stage robust control scheme improving the performance of an Activated Sludge Process is proposed. In the first stage, asymptotic command following the Substrate Concentration with simultaneous attenuation of the fluctuations of the dissolved oxygen Concentration is assured. The first stage is a pure dynamic controller. The second stage is a PID controller. Good performance of the proposed control scheme on the corresponding nonlinear ASP model is illustrated through extensive simulation experiments. The contribution of the paper can be summarized to the derivation of the following two results: An accurate to a wide range of inputs and disturbances, linearized generic model of the ASP and, most important, a linear robust controller that controls accurately the effluent Substrate Concentration without using measurements of it.

Fotis N. Koumboulis - One of the best experts on this subject based on the ideXlab platform.

  • Metaheuristic control of Substrate Concentration for an activated sludge process
    International Journal of Modelling Identification and Control, 2010
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, M.p. Tzamtzi, A. Stathaki
    Abstract:

    In this paper, a two-stage linear dynamic control scheme, using a metaheuristic approach, will be developed to control the effluent Substrate Concentration of an ASP. In the first stage, a static output feedback controller will be designed, using only measurements of the oxygen Concentration. In the second stage, an asymptotic non-linear estimator of the Substrate Concentration will be used and the estimate will be fed back through a PI controller. In particular, the model of the ASP will be presented both in its non-linear and linearised form. Based on the linearised approximation, a static inner loop controller will be designed using a metaheuristic search algorithm for the computation of the controller parameters. Following, an outer PI controller will be designed based on the linearised model, again using a metaheuristic search algorithm in order to compensate the influence of the non-linearities when the static controller is applied to the non-linear model. The performance of the overall closed loop system will be illustrated through simulation experiments.

  • Two-stage robust control of Substrate Concentration for an activated sludge process.
    ISA transactions, 2008
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, Robert E. King, A. Stathaki
    Abstract:

    A two-stage robust control scheme improving the performance of an Activated Sludge Process is proposed. In the first stage, asymptotic command following the Substrate Concentration with simultaneous attenuation of the fluctuations of the dissolved oxygen Concentration is assured. The first stage is a pure dynamic controller. The second stage is a PID controller. Good performance of the proposed control scheme on the corresponding nonlinear ASP model is illustrated through extensive simulation experiments. The contribution of the paper can be summarized to the derivation of the following two results: An accurate to a wide range of inputs and disturbances, linearized generic model of the ASP and, most important, a linear robust controller that controls accurately the effluent Substrate Concentration without using measurements of it.

Carolina Carvajal - One of the best experts on this subject based on the ideXlab platform.

  • biohydrogen production from tequila vinasses in an anaerobic sequencing batch reactor effect of initial Substrate Concentration temperature and hydraulic retention time
    Bioresource Technology, 2010
    Co-Authors: German Buitron, Carolina Carvajal
    Abstract:

    Abstract The effect of the temperature (25 and 35 °C), the hydraulic retention time, HRT, (12 and 24 h) and initial Substrate Concentration on hydrogen production from Tequila vinasse was studied using a sequencing batch reactor. When 25 °C and 12-h HRT were applied, only insignificant biogas quantities were produced; however, using 24 h of HRT and temperatures of 25 and 35 °C, biogas containing hydrogen was produced. A maximum volumetric hydrogen production rate of 50.5 mL H2 L−1 h−1 (48 mmol H2  L reactor - 1  d−1) and an average hydrogen content in the biogas of 29.2 ± 8.8% were obtained when the reactor was fed with 3 g COD L−1, at 35 °C and 12-h HRT. Methane formation was observed when the longer HRT was applied. Results demonstrated the feasibility to produce hydrogen from this waste without a previous pre-treatment.

Nikolaos D. Kouvakas - One of the best experts on this subject based on the ideXlab platform.

  • Metaheuristic control of Substrate Concentration for an activated sludge process
    International Journal of Modelling Identification and Control, 2010
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, M.p. Tzamtzi, A. Stathaki
    Abstract:

    In this paper, a two-stage linear dynamic control scheme, using a metaheuristic approach, will be developed to control the effluent Substrate Concentration of an ASP. In the first stage, a static output feedback controller will be designed, using only measurements of the oxygen Concentration. In the second stage, an asymptotic non-linear estimator of the Substrate Concentration will be used and the estimate will be fed back through a PI controller. In particular, the model of the ASP will be presented both in its non-linear and linearised form. Based on the linearised approximation, a static inner loop controller will be designed using a metaheuristic search algorithm for the computation of the controller parameters. Following, an outer PI controller will be designed based on the linearised model, again using a metaheuristic search algorithm in order to compensate the influence of the non-linearities when the static controller is applied to the non-linear model. The performance of the overall closed loop system will be illustrated through simulation experiments.

  • Two-stage robust control of Substrate Concentration for an activated sludge process.
    ISA transactions, 2008
    Co-Authors: Fotis N. Koumboulis, Nikolaos D. Kouvakas, Robert E. King, A. Stathaki
    Abstract:

    A two-stage robust control scheme improving the performance of an Activated Sludge Process is proposed. In the first stage, asymptotic command following the Substrate Concentration with simultaneous attenuation of the fluctuations of the dissolved oxygen Concentration is assured. The first stage is a pure dynamic controller. The second stage is a PID controller. Good performance of the proposed control scheme on the corresponding nonlinear ASP model is illustrated through extensive simulation experiments. The contribution of the paper can be summarized to the derivation of the following two results: An accurate to a wide range of inputs and disturbances, linearized generic model of the ASP and, most important, a linear robust controller that controls accurately the effluent Substrate Concentration without using measurements of it.

J S Vrouwenvelder - One of the best experts on this subject based on the ideXlab platform.

  • effect of flow velocity Substrate Concentration and hydraulic cleaning on biofouling of reverse osmosis feed channels
    Chemical Engineering Journal, 2012
    Co-Authors: A I Radu, M.c.m. Van Loosdrecht, J S Vrouwenvelder, Cristian Picioreanu
    Abstract:

    Abstract A two-dimensional mathematical model coupling fluid dynamics, salt and Substrate transport and biofilm development in time was used to investigate the effects of cross-flow velocity and Substrate availability on biofouling in reverse osmosis (RO)/nanofiltration (NF) feed channels. Simulations performed in channels with or without spacer filaments describe how higher liquid velocities lead to less overall biomass amount in the channel by increasing the shear stress. In all studied cases at constant feed flow rate, biomass accumulation in the channel reached a steady state. Replicate simulation runs prove that the stochastic biomass attachment model does not affect the stationary biomass level achieved and has only a slight influence on the dynamics of biomass accumulation. Biofilm removal strategies based on velocity variations are evaluated. Numerical results indicate that sudden velocity increase could lead to biomass sloughing, followed however by biomass re-growth when returning to initial operating conditions. Simulations show particularities of Substrate availability in membrane devices used for water treatment, e.g., the accumulation of rejected Substrates at the membrane surface due to Concentration polarization. Interestingly, with an increased biofilm thickness, the overall Substrate consumption rate dominates over accumulation due to Substrate Concentration polarization, eventually leading to decreased Substrate Concentrations in the biofilm compared to bulk liquid.

  • pressure drop increase by biofilm accumulation in spiral wound ro and nf membrane systems role of Substrate Concentration flow velocity Substrate load and flow direction
    Biofouling, 2009
    Co-Authors: J S Vrouwenvelder, M.c.m. Van Loosdrecht, C Hinrichs, W G J Van Der Meer, J C Kruithof
    Abstract:

    In an earlier study, it was shown that biofouling predominantly is a feed spacer channel problem. In this article, pressure drop development and biofilm accumulation in membrane fouling simulators have been studied without permeate production as a function of the process parameters Substrate Concentration, linear flow velocity, Substrate load and flow direction. At the applied Substrate Concentration range, 100-400 microg l(-1) as acetate carbon, a higher Concentration caused a faster and greater pressure drop increase and a greater accumulation of biomass. Within the range of linear flow velocities as applied in practice, a higher linear flow velocity resulted in a higher initial pressure drop in addition to a more rapid and greater pressure drop increase and biomass accumulation. Reduction of the linear flow velocity resulted in an instantaneous reduction of the pressure drop caused by the accumulated biomass, without changing the biofilm Concentration. A higher Substrate load (product of Substrate Concentration and flow velocity) was related to biomass accumulation. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. A decrease of Substrate load caused a gradual decline in time of both biomass Concentration and pressure drop increase. It was concluded that the pressure drop increase over spiral wound reverse osmosis (RO) and nanofiltration (NF) membrane systems can be reduced by lowering both Substrate load and linear flow velocity. There is a need for RO and NF systems with a low pressure drop increase irrespective of the biomass formation. Current efforts to control biofouling of spiral wound membranes focus in addition to pretreatment on membrane improvement. According to these authors, adaptation of the hydrodynamics, spacers and pressure vessel configuration offer promising alternatives. Additional approaches may be replacing heavily biofouled elements and flow direction reversal.