A multivariable control scheme in a two-stage anaerobic digestion system described by partial differential equations

Expanding the Potential of G‐Quadruplex Structures: Formation of a Heterochiral TBA Analogue

“…Several authors discussed control scheme design and control methods in relation to biogas process control. Methods range from classical control methods such as feedback and feedforward control to advanced model‐based and multivariable control systems 10–16. Thereby, the respective objectives are quite different and reach from stabilizing gas production to the prevention of disturbances by ammonia and acidification.…”

Process control, energy recovery and cost savings in acetic acid wastewater treatment

“…In any case, both pH control schemes are simplified and effective in comparison to other techniques applied. Their main advantage is the simplicity and reliability of the pH sensor, whereas no further specialized measurements, such as specific methanogenic activity (SMA) [8] or VFA [10,11], are required. Auxostatic pH control permits space-time loads of up to 45 kg COD/m 3 d during reactor start-up, whereas other process control techniques allowed space-time loads of about 1 [8] to 14 kg COD/m 3 d [15].…”

“…Modern biosensors and controllers are needed for ensuring continuous optimal performance of anaerobic reactors [4,5,[7][8][9][10][11]. Ince et al adjusted space time load during start-up of an anaerobic digester by determining specific methanogenic activity [8].…”

“…Inhibitory effects of microbial activity were detected in the influent of anaerobic digesters by [7,10], whereas overloading control was investigated by [4,7,9]. VFAs and COD (Chemical Oxygen Demand) in two anaerobic fixed bed (AFB) reactors were used as the key control parameters [11]. However, pH was already found to be a more important factor than VFA concentration for fast recovery of anaerobic digesters after organic overloading [12].…”

Control strategy for maximum anaerobic co-digestion performance

“…M endez-Acosta et al (2010) proposed a robust control scheme to regulate both the VFA concentration and total alkalinity (TA) in order to improve the operational stability of continuous AD processes. Aguilar-Garnica et al (2009) developed a multi-variable control scheme in a two-stage AD process to maintain the effluent COD and VFA concentrations at predetermined set-points. Nevertheless, most of those control strategies were designed for monodigestion where the control action was based on modifying the HRT or OLR but not the characteristics of the substrates.…”