Lessons learnt from 15 years of ICA in anaerobic digesters

Abstract

Anaerobic digestion plants are highly efficient wastewater treatment processes with inherent energy production. Despite these advantages, many industries are still reluctant to use them because of their instability confronted with changes in operating conditions. There is therefore great potential for application of instrumentation, control and automation (ICA) in the field of anaerobic digestion. This paper will discuss the requirements (in terms of on-line sensors needed, modelling efforts and mathematical complexity) but also the advantages and drawbacks of different control strategies that have been applied to AD high rate processes over the last 15 years.

Electrolysis-enhanced anaerobic digestion of wastewater

“…Wastewaters of various complexity can and are treated by anaerobic digestion (Alvarez and Lema, 2010;Fang et al, 2011;Salminen and Rintala, 2002;Steyer et al, 2006;Tait et al, 2009). However, its application for energy recovery is limited by the presence of hydrogen sulfide in the biogas, the slow hydrolysis of complex organic matter under anaerobic conditions, the high sensitivity of anaerobic microorganisms to variations in wastewater composition and the requirement of influent with a high concentration of organic matter (Leitao et al, 2006).…”

Control en Estaciones Depuradoras de Aguas Residuales: Estado actual y perspectivas

“…como se concluye en Rieger et al (2003). Medidas defectuosas pueden originar desviaciones en el efluente que acaben en violaciones de los límites de descarga establecidos o incrementar los costes de operación tal como se muestra en Steyer et al (2006). En este sentido, las plataformas benchmark pueden utilizarse para mostrar la validez de las estrategias y algoritmos propuestos en presencia de estos fallos y evaluar la repercusión de los mismos en el funcionamiento global de la planta.…”

Pilot-Scale Validation of a New Sensor for On-Line Analysis of Volatile Fatty Acids and Alkalinity in Anaerobic Wastewater Treatment Plants

“…The instability of the anaerobic digestion process is usually related to the variation of wastewater quality and flow rate (Steyer et al, 2006). For this reason, the validation experiments were defined as organic and hydraulic overload scenarios.…”

“…In the acetogenesis step, volatile acids longer than two carbons are converted to acetic acid, CO 2 , and H 2 , which in turn, become CH 4 through methanogenesis (Speece, 1996). These process steps must be well balanced to prevent volatile fatty acid (VFA) accumulation and thus to avoid a sudden drop in system pH, which may lead to complete failure of the conversion process (Gujer and Zehnder, 1983;Switzembaum et al, 1990;Ahring et al, 1995;Tay and Zhang, 2000;Lahav et al, 2002a;Steyer et al, 2006). Successful operation of anaerobic process depends, among other operational parameters and conditions, on maintaining a system pH between 6.6 and 7.4 (Moosbrugger et al, 1992;Lahav et al, 2002b).…”