Monitoring of anaerobic digestion processes: A review perspective

Abstract

The versatility of anaerobic digestion (AD) as an effective technology for solving central challenges met in applied biotechnological industry and society has been documented in numerous publications over the past many decades. Reduction of sludge volume generated from wastewater treatment processes, sanitation of industrial organic waste, and benefits from degassing of manure are a few of the most important applications. Especially, renewable energy production, integrated biorefining concepts, and advanced waste handling are delineated as the major market players for AD that likely will expand rapidly in the near future. The complex, biologically mediated AD events are far from being understood in detail however. Despite decade-long serious academic and industrial research efforts, only a few general rules have been formulated with respect to assessing the state of the process from chemical measurements. Conservative reactor designs have dampened the motivation for employing new technologies, which also constitutes one of the main barriers for successful upgrade of the AD sector with modern process monitoring instrumentation. Recent advances in Process Analytical Technologies (PAT) allow complex bioconversion processes to be monitored and deciphered using e.g. spectroscopic and electrochemical measurement principles. In combination with chemometric multivariate data analysis these emerging process monitoring modalities carry the potential to bring AD process monitoring and control to a new level of reliability and effectiveness. It is shown, how proper involvement of process sampling understanding, Theory of Sampling (TOS), constitutes a critical success factor. We survey the more recent trends within the field of AD monitoring and the powerful PAT/TOS/chemometrics application potential is highlighted. The Danish co-digestion concept, which integrates utilisation of agricultural manure, biomass and industrial organic waste, is used as a case study. We present a first foray for the next research and development perspectives and directions for the AD bioconversion sector.

Evaluation of an electronic nose for the early detection of organic overload of anaerobic digesters

“…Multivariate data analysis is adapted to multivariate processes such as anaerobic digestion and to give relevant and uncomplicated information of the process state and warn off outlier situations compared with the steady-state process [11]. However, the training data set to calculate the distance from the steady-state process must be carefully managed [11,30].…”

“…However, the training data set to calculate the distance from the steady-state process must be carefully managed [11,30]. True performance of a gas sensor array for biogas process monitoring could only be estimated by extending the present work to conditions prevailing in real agricultural situations while comparing results with VFA monitoring in the liquid phase, the latter being a well accepted method for identifying organic overload state the anaerobic process [8,[37][38][39][40].…”

“…For agricultural AD plants, robustness and simplicity must necessarily be part of the process analyzer design [11].…”

Evaluating an e-nose ability to detect biogas plant efficiency: a case study

“…VFAs detection can be performed through fluorescence spectroscopy (Pearce et al 2003;Madsen et al 2011), near-infrared (NIR) spectroscopy (Nicolas et al 2001), titration and gas chromatography (Cimander et al 2002).…”

Dimensioning of Digestion Chamber for Upgrading of Gas Recovery at Wastewater Treatment Plant

“…Conservative methods of dimensioning such as assumption of solid retention time (SRT) may lead to over dimensioning of sludge digestion chambers [5,7,9]. Previous attempts towards prediction or assessment of design parameters did not result in universal reliable design method [10,11]. Other proposed methods are suitable for general description of the phenomena rather than for engineering purposes [6,12,13].…”