pH-controlled Process Research Articles

Rancang Bangun Akuarium Portable Menggunakan Teknologi Internet Of Things Untuk Budidaya Ikan Hias

Portable aquarium designed with an automation system for controlling pH levels and temperature information. pH levels are measured using a pH sensor E-201-C and temperature is measured with a DS18B20 sensor. The pH control process is carried out by adding liquid pH up and pH down and is realized with a solenoid valve. The purpose of making this portable aquarium is to control the pH value of the water in the aquarium and provide information about the water temperature. Into this portable aquarium system have been inputted standard values of pH and temperature for each type of fish. This system will work automatically to adjust the living environment of ornamental fish according to their respective needs. The pH control system can work if the pH measurement value indicates a high pH or low pH condition and under these conditions, the water will flow into the pH adjustment tube to control. If the pH measurement value states that the pH is high then the pH down control liquid will flow and if the pH measurement value states that the pH is low then the pH up control liquid will flow. This system has been proven to be able to maintain the environmental conditions of ornamental fish with the results of pH and temperature measurements being 7.48 -7.8 and 28.87 – 29.55 °C.

A Rapid and Reversible pH Control Process for the Formation and Dissociation of Lignin Nanoparticles.

As a new and green type of nanomaterials, lignin nanoparticles (LNPs) have been considered as high-value renewable materials for application in many fields. However, the industrialization of LNPs faces many challenges, such as high manufacturing costs and small-scale production. Here, a simple but rapid and reversible approach for the fabrication of LNPs was provided via switching pH environments. The LNPs were regularly shaped in the acetonitrile/water system, and their size appeared to be very homogeneous. The alternation of forming and dissolving of LNPs could be repeated many times simply by alternately adding acid and alkaline solutions. There was little difference in the molecular structures between the original and regenerated LNPs. In addition, the consumption of solvents for LNPs production was only 200 mL g-1 , reduced by more than 10 times compared with conventional solvent exchange methods. The concentration of LNPs in the solution also improved to 5.0 g L-1 . This study not only provides a new, simple, and effective strategy for the fabrication of LNPs but also paves the way towards their real green production and application.

Effects of process conditions on simultaneous removal and recovery of boron from boron-laden wastewater using improved bipolar membrane electrodialysis (BMED)

The anthropogenic emission of boron to the environment has posed a serious risk to human and animal health due to its non-biodegradability and the resulting accumulation in the body. Bipolar membrane electrodialysis (BMED) has been proven to be an economical and effective process to remove and recover boron from wastewater. In this work, we verified multiple process parameters to evaluate the efficiency of boron removal and recovery using intermittent and continuous BMED modes. Higher initial boron concentrations appeared to reduce the boron processing rate, but this reduction may be ameliorated by increasing current density. Similarly, higher initial pH was observed to retard the removal rate of boron with increasing mass transfer rate. When solution pH was controlled from 9.5 to 10.5 and the current density was 6.36 A/m2 under maximum allowable voltage of 12 V, boron removal and recovery efficiencies were 98.6% and 86.5%, respectively. During the pH-control process, current variation pattern indicated that current density was associated with initial boron concentrations in salt apartment. When the current variation pattern was applied to a five-cycle sequential feed-batch BMED process, it accurately reflected the timing of complete boron removal and recovery on a batch fill-and-draw process. The overall boron removal and recovery efficiencies were 98.53% and 81.2%, respectively, with an energy consumption of 31.5 Wh/g. Under these conditions, the final boron concentrations in effluent were less than 10 mg/L, as required by the Taiwan Environmental Protection Administration (EPA). Overall, BMED is a cost-effective treatment process for boron-containing wastewater. The proposed process indicator reflecting sequential BMED process progression based on process information will further elucidate the automatic process control in industrial applications.

DEVELOPMENT AND STUDY OF SOLUTION UNIT FOR AUTOMATED AEROPONICS GROWING PLANT

Research and development of a solution node of an automated plant for aeroponic growing have been considered. The paper describes the options for storing mother solutions, the methods for their dilution, automation of the Ph control process, the methods for selective assessment of the concentration of nutrients by NPK. A number of key problems that limit the full automation of solution nodes in a closed cycle of plant growing have been highlighted.

Software Components for Smart Industry Based on Microservices: A Case Study in pH Control Process for the Beverage Industry

Modern industries require constant adaptation to new trends. Thus, they seek greater flexibility and agility to cope with disruptions, as well as to solve needs or meet the demand for growth. Therefore, smart industrial applications require a lot of flexibility to be able to react more quickly to continuous market changes, offer more personalized products, increase operational efficiency, and achieve optimum operating points that integrate the entire value chain of a process. This requires the capture of new data that are subsequently processed at different levels of the hierarchy of automation processes, with requirements and technologies according to each level. The result is a new challenge related to the addition of new functionalities in the processes and the interoperability between them. This paper proposes a distributed computational component-based framework that integrates communication, computation, and storage resources and real-time capabilities through container technology, microservices, and the publish/subscribe paradigm, as well as contributing to the development and implementation of industrial automation applications by bridging the gap between generic architectures and physical realizations. The main idea is to enable plug-and-play software components, from predefined components with their interrelationships, to achieve industrial applications without losing or degrading the robustness from previous developments. This paper presents the process of design and implementation with the proposed framework through the implementation of a complex pH control process, ranging from the simulation part to its scaling and implementation to an industrial level, showing the plug-and-play assembly from a definition of components with their relationships to the implementation process with the respective technologies involved. The effectiveness of the proposed framework was experimentally verified in a real production process, showing that the results scaled to an industrial scale comply with the simulated design process. A qualitative comparison with traditional industrial implementations, based on the implementation requirements, was carried out. The implementation was developed in the beverage production plant “Punta Delicia”, located in Colima, Mexico. Finally, the results showed that the platform provided a high-fidelity design, analysis, and testing environment for cyber information flow and their effect on the physical operation of the pH control.

Model-Free Adaptive Control of pH Value of Wet Desulfurization Slurry under Switching of Multiple Working Conditions

In limestone-gypsum wet flue gas desulfurization process, the change process of pH value of slurry in absorption tower is a typical nonlinear system with time delay and various uncertainties, so it is difficult to establish an accurate mathematical model of slurry pH control process. According to the pH control process of the slurry of wet flue gas desulfurization process, a model-free adaptive control algorithm based on compact form dynamic linearization (CFDL-MFAC) is designed to realize the tracking control of the pH value of the slurry. Due to various interference factors in the pH control process of slurry in absorption tower, it is easy to cause jump change of control system parameters and even structure. Therefore, a model-free adaptive control algorithm based on switching strategy is proposed in this paper. According to different working conditions, several model-free adaptive controllers are established. The stability of the algorithm is analyzed for the two cases of fixed system parameters and jumping system parameters. It was found that the model-free adaptive controller based on the switching strategy can switch multiple controllers under the condition of system parameter jump, so as to realize the fast tracking control of the slurry pH value of the system absorption tower under different working conditions. Through this method, the overshoot can be reduced and the control quality can be improved.

Robust indirect adaptive sliding model control for Wiener nonlinear systems

ABSTRACTWiener model structures have attracted considerable attentions due to their powerful modelling abilities to solve industrial problems. This paper considers a new class of Wiener model structure, which consists of a linear transfer function and a radial basis function (RBF) network. Based on this structure, the unstable zero-dynamics, the added disturbances and the approximation errors problems can be dealt with. Since the model parameters are assumed unknown, we develop a new indirect adaptive control scheme. It is a consensus that the certainty equivalence principle is the key that connects the adaptation algorithm with the control law. This paper explains that, for indirect adaptive control of Wiener model, this principle may not be applied directly. The main contribution of this paper is to address this issue by presenting a rigorous theoretical analysis. Representative examples including a simulated pH process control problem are studied to test the control performance. Comparison results indicate that the proposed controller has much wider applicability than some alternative methods, especially for its improved performance and smoother adaptation.

Fractional Order Set-point Weighted PID Controller for pH Neutralization Process Using Accelerated PSO Algorithm

Control of pH processes is highly challenging due to high nonlinearity and sensitivity around the equilibrium point. PID controllers being simple and the most widely used perform poorly with changing set-point and are limited to certain operating regions. Thus, they are inadequate for such applications without upgrading. In this paper, a fractional order set-point weighted PID (\(\mathrm {SWPI^{\lambda }D^{\mu }}\)) controller is designed for pH neutralization process. The objective is to achieve adequate set-point tracking and effective load regulation through smooth control action. The controller parameters are tuned using accelerated particle swarm optimization which uses only global best position to achieve faster convergence. Simulation results show that for both standard and industrial configurations of the proposed approach, better performance in terms of set-point tracking, disturbance rejection and sensitivity to model parameter variation is achieved compared to PID, fractional order PID (\(\mathrm {PI^{\lambda }D^{\mu }}\)) and SWPI-D.

Treatment of high strength acidic wastewater using passive pH control

A passive pH control system to process high strength (COD∼20,000mgl−1) acidic wastewater without alkali addition was developed. The low-energy wastewater treatment system consisted of a packed bed up-flow anaerobic reactor followed by an aerobic trickling filter, both of which used biochar as the biofilm support media. The passive pH control process relied on controlled recycle of the effluent leaving the anaerobic stage to adjust the pH of the acidic feedstock. The anaerobic reactor was able to achieve steady state reductions in total chemical oxygen demand (TCODred) above 91% and the combined system (anaerobic-aerobic) achieved COD reductions above 97% without alkali addition. Methane production was 0.311m3 per kg COD reduced. The system was also able to produce an effluent that met EPA regulations in terms of BOD5 and TSS, possessed a near neutral pH, and was highly nitrified.

Comparison Analysis of Model Predictive Controller with Classical PID Controller For pH Control Process

pH control plays a important role in any chemical plant and process industries. For the past four decades the classical PID controller has been occupied by the industries. Due to the faster computing technology in the industry demands a tighter advanced control strategy. To fulfill the needs and requirements Model Predictive Control (MPC) is the best among all the advanced control algorithms available in the present scenario. The study and analysis has been done for First Order plus Delay Time (FOPDT) model controlled by Proportional Integral Derivative (PID) and MPC using the Matlab software. This paper explores the capability of the MPC strategy, analyze and compare the control effects with conventional control strategy in pH control. A comparison results between the PID and MPC is plotted using the software. The results clearly show that MPC provide better performance than the classical controller.

An electrochemical platform for localized pH control on demand.

Solution pH is a powerful tool for regulating many kinds of chemical activity, but is generally treated as a static property defined by a pre-selected buffer. Introducing dynamic control of pH in space, time, and magnitude can enable richer and more efficient chemistries, but is not feasible with traditional methods of titration or buffer exchange. Recent reports have featured electrochemical strategies for modifying bulk pH in constrained volumes, but only demonstrate switching between two preset values and omit spatial control entirely. Here, we use a combination of solution-borne quinones and galvanostatic excitation to enable quantitative control of pH environments that are highly localized to an electrode surface. We demonstrate highly reproducible acidification and alkalinization with up to 0.1 pH s(-1) (±0.002 pH s(-1)) rate of change across the dynamic range of our pH sensor (pH 4.5 to 7.5) in buffered solutions. Using dynamic current control, we generate and sustain 3 distinct pH microenvironments simultaneously to within ±0.04 pH for 13 minutes in a single solution, and we leverage these microenvironments to demonstrate spatially-resolved, pH-driven control of enzymatic activity. In addition to straightforward applications of spatio-temporal pH control (e.g. efficiently studying pH-dependencies of chemical interactions), the technique opens completely new avenues for implementing complex systems through dynamic control of enzyme activation, protein binding affinity, chemical reactivity, chemical release, molecular self-assembly, and many more pH-controlled processes.

Pole-placement self-tuning control of nonlinear Hammerstein system and its application to pH process control

By taking advantage of the separation characteristics of nonlinear gain and dynamic sector inside a Hammerstein model, a novel pole placement self tuning control scheme for nonlinear Hammerstein system was put forward based on the linear system pole placement self tuning control algorithm. And the nonlinear Hammerstein system pole placement self tuning control (NL-PP-STC) algorithm was presented in detail. The identification ability of its parameter estimation algorithm of NL-PP-STC was analyzed, which was always identifiable in closed loop. Two particular problems including the selection of poles and the on-line estimation of model parameters, which may be met in applications of NL-PP-STC to real process control, were discussed. The control simulation of a strong nonlinear pH neutralization process was carried out and good control performance was achieved.

Combustion Syntheses of Co3O4 Powders Using Different Fuels

Co3O4 powders are used as pigment in solar selective paints. In this work, two new gel-combustion processes for the synthesis of Co3O4 nanopowders with lysine (Lys) or ethylenediaminetetraacetic acid (Edta) as fuel are presented. The first route is a conventional, stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. The samples were calcined in air at 500°C. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the optical properties of the pigments were assessed with a spectrophotometer. In all cases, powders exhibited the Co3O4 crystalline structure. A minimum crystallite average size of 19nm for powders obtained by the “stoichiometric/Lys” combustion route was observed, meanwhile, a maximum value of 47nm was stated for powders obtained by the “non-stoichiometric/Edta” combustion process. The average particle size ranged between 50 and 100nm. The powders obtained by the stoichiometric nitrate–lysine route were selected to study its optical properties, their solar absorption was 88%, compared with the references, evidencing their aptitude to be used in solar absorbent paints.

High performance of nanoscaled Fe2O3 catalyzing UV-Fenton under neutral condition with a low stoichiometry of H2O2: Kinetic study and mechanism

Kinetics and mechanism of nano-Fe2O3 catalyzing UV-Fenton were investigated in this study with catechol as model pollutant. This type of heterogeneous UV-Fenton was proven to be characteristic of a wide pH range from mildly acidic to slightly alkaline and low H2O2 requirement accompanied with H2O2 utilization efficiency of larger than 1.0. Experiments of degradation under neutral condition with and without pH process control and analysis of several carboxylic acids were performed to find out the reason for treatment effectiveness under neutral condition. Kinetics study using the pseudo-first-order equation was performed to evaluate the effects of initial pH, H2O2 dose, nano-Fe2O3 dose, and reaction temperature on the rate constant of COD reduction, it was interesting to find the rate constant was similar among initial pH values from 3.0 to 8.0. Based on the data of rate constant under different temperatures, Ea (activation energy), ΔH (enthalpy change) and ΔS (entropy change) were calculated to be 45.1(±6.3) kJ/mol, 42.6(±6.3) kJ/mol and −148.0(±20.8) J/K/mol, respectively. Radical identification experiments based on inhibition of methylene blue degradation under respective scavenger for HO (hydroxyl radical), O21 (singlet oxygen) and O2− (superoxide radical) showed HO, O21 and O2− participated in nano-Fe2O3 catalyzing UV-Fenton. Presence of oxygen could greatly enhance the degradation rate compared with the case of bubbling nitrogen, and a possible mechanism of catechol oxidation in nano-Fe2O3 catalyzing UV-Fenton was proposed. At last, reusability and stability of nano-Fe2O3 were evaluated in six repeated runs. This study will provide some deep understanding of nano-Fe2O3 catalyzing UV-Fenton with respect to technical advantage and oxidation mechanism.

A Two-stage pH and Temperature Control with Substrate Feeding Strategy for Production of Gamma-aminobutyric Acid by Lactobacillus brevis CGMCC 1306

Methods to optimize the production of gamma-aminobutyric acid (GABA) by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was preferable to GABA formation. The optimal temperature for cell growth (35 °C) was lower than that for GABA formation (40 °C). In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L−1 at 72 h, while it was 398.63 mmol·L−1 with one stage pH and temperature control process, in which cultivation conditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate (L-MSG) concentrations, the two-stage control fermentation with substrate feeding strategy was applied to GABA production, with 106.87 mmol (20 g) L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L−1 at 72 h with the fermentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.

Removal of boron in a multistage SWRO system with pre-crystallization

Recently, the desalination facilities use the membrane method that it is more effective and economical than the thermal method. And, the most recent a multistage seawater reverse osmosis (SWRO) system has been applied to increase the recovery rate. A multistage SWRO system has some more economical advantages for desalination than a single-stage SWRO system, such as high recovery rate, reuse of the brine pressure, and decreased brine quantity. However, there is still a problem related to the boron concentration exceeding drinking water quality standard. Therefore, the purpose of this study was to discuss the removal of boron using a multistage SWRO system with pre-crystallization for the removal of scale-causing substances and to change the form of boron. As a result, the boron concentration in permeate of the second stage-SWRO membrane in the pre-crystallization process (permeate (2)) was 0.48 mg/L, and that via the conventional process was 2.87 mg/L. And, the recovery rate of the experiment that applied pre-crystallization process was observed to be higher than that of the conventional process at the same operating pressure. The pH of the permeate (2) was weakly basic, at 8.53; therefore, it was concluded that the pH control process could be omitted from the post-treatment.

Improvement of welan gum production and redistribution of metabolic flux under pH control process in Alcaligenes sp. CGMCC2428

Batch fermentations of welan gum from Alcaligenes sp. CGMCC2428 at pH values of 5.5 ∼ 7.0 were studied. Based on the kinetic analysis, a pH control process for improving welan production was developed. By maintaining the culture pH at 7.0, the process significantly improved the maximal welan concentration and productivity to reach 25.1 ± 0.65 g/L and 0.42 ± 0.003 g/L/h, respectively, compared with those in native pH processes where pH value would decrease from 7.0 to 5.1 (18.5 ± 0.72 g/L and 0.28 ± 0.002 g/L/h). This improvement may be due to the increased metabolic flux of glucose-1-phosphate to welan induced by pH control process. Furthermore, scale-up fermentation under controlled pH was implemented using 300-L fermentor. The highest welan concentration of 27.5 ± 0.97 g/L was obtained. This simplified process proved effective in industry fermentation for high welan production.

Comparison between backstepping and input–output linearization techniques for pH process control

In this work performances of adaptive backstepping controller (BSC) and globally linearizing controller (GLC) are compared for pH control. First, based on the system full order model a GLC has been designed and it has been shown that this controller is identical to BSC proposed in the literature. Next in order to avoid state estimator design, BSC and GLC are designed based on pH reduced order model and their identities have been established. Through computer simulations, it has been shown that the performance of non-adaptive GLC designed based on reduced order model is better than that of adaptive BSC designed based on pH full order model which requires state measurement for implementation. Finally, the effectiveness of GLC designed based on the reduced order model in load rejection and set-point tracking has been demonstrated through simulation and experimental studies.

Control of pH process using double-control scheme

Control of pH is mostly needed in continuous process industries and is difficult and challenging due to its time-varying and nonlinear nature of the chemical or biological process. Conventional controllers do not incorporate nonlinear dynamics of the entire pH range (both acid and alkali) and do not show good performance. Dynamics based on specific process nonlinearity of two different ranges is used to design double-control scheme in a feedback structure to enhance the performance of pH process. The mathematical model of pH for a weak acid-strong base is used to design IMC based PID double-controller scheme which provides outstanding set-point tracking and disturbances rejection simultaneously to control pH processes.

Production of ε-poly-l-lysine using a novel two-stage pH control strategy by Streptomyces sp. M-Z18 from glycerol

The production of ε-poly-L: -lysine (ε-PL) by Streptomyces sp. M-Z18 from glycerol was investigated in a 5-L jar-fermenter. Batch fermentations by Streptomyces sp. M-Z18 at various pH values ranging from 3.5 to 4.5 were studied. Based on the analysis of the time course of specific cell growth rate and specific ε-PL formation rate, a novel two-stage pH control strategy was developed to improve ε-PL production by shifting the culture pH from 3.5 to 3.8 after 36 h of cultivation. By applying the strategy, the maximal ε-PL concentration and productivity had a significant improvement and reached 9.13 g L(-1) and 4.76 g L(-1) day(-1), respectively, compared with those in one-stage pH control process where the pH value is controlled at 3.5 (7.83 g L(-1) and 3.13 g L(-1) day(-1)). Fed-batch fermentation with two-stage pH control strategy was also applied to produce ε-PL; final ε-PL concentration of 30.11 g L(-1) was obtained, being 3.3-fold greater than that of batch fermentation. To our knowledge, it is the first report on production of ε-PL from glycerol in fermenter scale and achievement of high ε-PL production with two-stage pH control strategy.