“The IWA Anaerobic Digestion Modelling Task Group was established in 1997 at the 8th World Congress on Anaerobic Digestion (Sendai, Japan) with the goal of developing a generalised anaerobic digestion model. The structured model includes multiple steps describing biochemical as well as physicochemical processes. The biochemical steps include disintegration from homogeneous particulates to carbohydrates, proteins and lipids; extracellular hydrolysis of these particulate substrates to sugars, amino acids, and long chain fatty acids (LCFA), respectively; acidogenesis from sugars and amino acids to volatile fatty acids (VFAs) and hydrogen; acetogenesis of LCFA and VFAs to acetate; and separate methanogenesis steps from acetate and hydrogen/CO2. The physico-chemical equations describe ion association and dissociation, and gas-liquid transfer. Implemented as a differential and algebraic equation (DAE) set, there are 26 dynamic state concentration variables, and 8 implicit algebraic variables per reactor vessel or element. Implemented as differential equations (DE) only, there are 32 dynamic concentration state variables.”
“A state estimator and various model-based control systems have been designed for a real anaerobic digestion (AD) pilot reactor fed with dairy manure. The model used is a modified Hill model which is a relatively simple dynamical AD process model. The state estimator is an Unscented Kalman Filter (UKF) which uses only methane gas flow measurement to update its states. The model and the state estimates are used in different control systems. One of the control systems aims at controlling the methane gas flow to a setpoint. Simulations indicate that the setpoint tracking performance of a predictive control system is considerably better comparing with PI control, while disturbance compensation is not much better. Consequently, assuming the setpoint is constant, the PI controller competes well with the predictive controller. A successful application of predictive control of the real reactor is presented. Also, three different control systems aiming at retaining the reactor at an operating point where the volatile fatty acids (VFA) concentration has a maximum, safe value are designed. A simulation study indicates that the best control solution among the three alternatives is PI control based on feedback from estimated VFA.”
Early Anaerobic Digestion Model Studies – A List of Published Papers on all aspects of AD Technology
- CECCHI, F. and Others (1988) “State of the art of R&D in the anaerobic digestion process of municipal solid waste in Europe”, Biomass, 16, pp257-284.
- DE BAERE, L and SIX, W. (1989) “Dry anaerobic digestion of agro-industrial wastes”, in Landfill Gas and Anaerobic Digestion of Solid Waste”, Proceedings of International Conference held in Chester, England, October 1988, (Y.R.Alston and G.E. Richards – editors), Harwell Laboratory, UKAEA, Oxon. 0X11 ORA, pp545-549.
- HUBB, J.M. and others (1988) “Effect of lignin on the anaerobic degradation of (ligno) cellulosic wastes by rumen microorganisms“, Applied Microbiology and Biotechnology,29, pp408-412.
- JEWELL, W.J. and others (1982) “Agtricultural and high strength wastes”, In Anaerobic Digestion 1981, Proceedings of the Second International Symposium on Anaerobic Digestion, AD'81, (D.E. Hughes and others editors), Travemunde, Germany, Elsevier Biomedical Press, Amersterdam, New York, Oxford, ppl51-168.
- McCARTY, P.L. (19 64) “Anaerobic waste treatment fundamentals, part three – toxic materials and their control”, Public Works November, 95, (11), pp91-94.
- PFEFFER, J.T. (1979) “Domestic refuse as a feed for digesters”, InAnaerobic Digestion 1981, Procedings of the First International Symposium on Anaerobic Digestion, AD 79, (D.A. Stafford, B.I. Wheatley & D.E. Hughes – editors), Cardiff, Applied Science Publishers Ltd, ppl87-203.
- PFEFFER, J.T. (1987) “Evaluation of the RefCOM proof- of-concept experiment” In Energy from Biomass and wastes X, (D.L. Klass – editor), Elsevier Applied Science, London and IGT, Chicago, ppll49-1171.
- WUJCIK, W.J. (1980) “Dry anaerobic fermentation”, Ph.D. Dissertation, Dept. of Agricultural Engineering, Cornell University, USA.
- ZAOUI, R. (1989) “VALORGA digestion process”, In Landfill Gas and Anaerobic Digestion of Solid Waste, Proceedings of International Conference held in Chester, England, October
1988, (Y.R. Alston and G.E. Richards – editors), Harwell Laboratory, UKAEA, Oxon. 0X11 ORA, pp481-500.