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

• Published in: Biotechnology and bioengineering 2013-08, Vol.110 (8), p.2131-2139
• Main Authors: Méndez-Acosta, H.O., Hernandez-Martinez, E., Jáuregui-Jáuregui, J.A., Alvarez-Ramirez, J., Puebla, H.
• Format: Article
• Language: English
• Subjects: anaerobic sequential batch reactors; Anaerobic treatment; Anaerobiosis; Bioreactors - microbiology; Correlation analysis; Environmental monitoring; Environmental policy; Fractal analysis; Hydrogen-Ion Concentration; Industrial Waste; Measurement; on-line monitoring; On-line systems; Policies; Reactors; Sensors; tequila vinasses; Time Factors; Time series; Waste Water - microbiology; wastewater treatment; Water treatment
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.24838

Efficient monitoring and control schemes are mandatory in the current operation of biological wastewater treatment plants because they must accomplish more demanding environmental policies. This fact is of particular interest in anaerobic digestion processes where the availability of accurate, inexpensive, and suitable sensors for the on‐line monitoring of key process variables remains an open problem nowadays. In particular, this problem is more challenging when dealing with batch processes where the monitoring strategy has to be performed in finite time, which limits the application of current advanced monitoring schemes as those based in the proposal of nonlinear observers (i.e., software sensors). In this article, a fractal time series analysis of pH fluctuations in an anaerobic sequential batch reactor (AnSBR) used for the treatment of tequila vinasses is presented. Results indicated that conventional on‐line pH measurements can be correlated with off‐line determined key process variables, such as COD, VFA and biogas production via some fractality indexes. Biotechnol. Bioeng. 2013; 110: 2131–2139. © 2013 Wiley Periodicals, Inc. Fractal analysis can be used as an effective tool for on‐line monitoring of the evolution of key process variables such as COD, total VFA and the biogas production in anaerobic sequential batch reactors (AnSBR). The fact that the evolution of such variables can be followed with a simple pH measurement is of special interest for industrial application, and opens a wide rage of possibilities for the proposal of advanced but inexpensive monitoring and control schemes.