Monitoring anaerobic sequential batch reactors via fractal analysis of pH time series

Méndez‐Acosta, Hugo Oscar; Hernández‐Martínez, Eliseo; Jáuregui-Jáuregui, J.A.; Álvarez‐Ramírez, José; Puebla, Héctor

doi:10.1002/bit.24838

Cited by 18 publications

(8 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The presence of different values of the Hurst exponent suggests that the R/S analysis can identify three characteristic phenomena immersed in the fluctuations of the pH series. These zones correspond to those reported in the anaerobic digestion of whey [37] and tequila vinasse [35,36], where each region was attributed to a different anaerobic digestion stage. Based on the above observations, Zone 1 is related to hydrolysis, Zone 2 corresponds with the acidogenesis and acetogenesis stages, and Zone 3 is related to methanogenesis.…”

Section: R/s Analysissupporting

confidence: 86%

“…In the last few years, multiscale data-driven methods based on fractal analysis have shown great potential to infer the key variables of the process. Méndez-Acosta et al [35] proposed the rescaled range (R/S) analysis of pH time series obtained from an up-flow reactor for the anaerobic digestion of tequila vinasses, where high correlations between the multiscale indices and critical variables of the process (i.e., COD, VFA, and biogas production) were determined. Similar results were found by Hernandez-Martinez et al [36] applying multiscale analysis in pH time series obtained from anaerobic treatment of tequila vinasses in continuous digesters (FBR and CSTR).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

et al. 2021

View full text Add to dashboard Cite

Anaerobic treatment is a viable alternative for the treatment of agro-industrial waste. Anaerobic digestion reduces organic load and produces volatile fatty acids (VFA), which are precursors of value-added products such as methane-rich biogas, biohydrogen, and biopolymers. Nowadays, there are no low-cost diagnosis and monitoring systems that analyze the dynamic behavior of key variables in real time, representing a significant limitation for its practical implementation. In this work, the feasibility of using the multiscale analysis to diagnose and monitor the key variables in VFA production by anaerobic treatment of raw cheese whey is presented. First, experiments were carried out to evaluate the performance of the proposed methodology under different operating conditions. Then, experimental pH time series were analyzed using rescaled range (R/S) techniques. Time-series analysis shows that the anaerobic VFA production exhibits a multiscale behavior, identifying three characteristic regions (i.e., three values of Hurst exponent). In addition, the dynamic Hurst exponents show satisfactory correlations with the chemical oxygen demand (COD) consumption and VFA production. The multiscale analysis of pH time series is easy to implement and inexpensive. Hence, it could be used as a diagnosis and indirect monitoring system of key variables in the anaerobic treatment of raw cheese whey.

show abstract

Section: R/s Analysissupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

et al. 2021

View full text Add to dashboard Cite

show abstract

“…A Waters 600 high‐performance liquid chromatograph, using a 2487 absorbance detector with a wavelength of 204 nm and Alltech OA‐1000 column which is specific for organic acids, was used to measure total VFA concentration reported as acetic acid. Finally, the biogas composition was determined using gas chromatography with a PerkinElmer AutoSystem XL with a TCD detector and an Alltech packed Hayesep D 100/120 column …”

Section: Methodsmentioning

confidence: 99%

Modeling pH and temperature effects on the anaerobic treatment of tequila vinasses

Moguel-Castañeda

Puebla

Méndez‐Acosta

et al. 2020

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

BACKGROUND An unstructured mathematical model is proposed to evaluate the effect of key variables on the anaerobic digestion of tequila vinasses and to determine the operating conditions that improve biogas production. Most of the models currently reported do not consider the simultaneous effects of pH and temperature on the process kinetics. Instead, they only recognize the specific operational conditions under which the experiments were conducted. Hence, this work presents a mathematical model that considers the effects of pH and temperature on methane production. RESULTS Experimental data were obtained from the anaerobic treatment of tequila vinasses conducted in a sequencing batch reactor, which was evaluated at two temperatures (32 and 38 °C) and two pH values (7 and 8) to validate the proposed model. Parameter estimation was performed using the Levenberg–Marquardt algorithm yielding a simplified model with high determination coefficients (R2 > 0.99). Moreover, kinetic parameters estimated were consistent physically and statistically. CONCLUSIONS Numerical simulations provide the operating conditions under which methane production can be favored. Therefore, the proposed model might be advantageous in predicting the maximum methane production rate and the maximum organic loading rate that could be used without risking the stability of an anaerobic digestion process. © 2020 Society of Chemical Industry

show abstract

“…Also, an H is obtained on the entire axial axis that changes with each movement of the window. This procedure generates an array of values of the fractal index for each time 25, 26.…”

Section: Time‐series Analysismentioning

confidence: 99%

Multiscale Analysis to Determine the Sensitive Zones for Temperature Sensor Location in Tubular Reactors

et al. 2021

View full text Add to dashboard Cite

The sensitivity of benchmark tubular reactors subject to temperature and concentration of external perturbations was investigated. Two case studies were evaluated, a pseudo‐homogeneous axial dispersion dimensionless tubular reactor and a heterogeneous tubular reactor to produce maleic anhydride. For the dimensionless reactor model, the highest sensitivities in the reactor were located at the center and at the outlet for temperature and concentration disturbances, respectively, while for the heterogeneous reactor model the sensitivity does not undergo significant changes with feed disturbances. When variations in the most sensitive position occur, a cascade controller can be improved using multiple temperature sensors. The evaluation on weighting assignment of the temperature measurements for the cascade control scheme is also described.

show abstract

Monitoring anaerobic sequential batch reactors via fractal analysis of pH time series

Cited by 18 publications

References 34 publications

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

Diagnosis and Monitoring of Volatile Fatty Acids Production from Raw Cheese Whey by Multiscale Time-Series Analysis

Modeling pH and temperature effects on the anaerobic treatment of tequila vinasses

Multiscale Analysis to Determine the Sensitive Zones for Temperature Sensor Location in Tubular Reactors

Contact Info

Product

Resources

About