Abstract
The main focus of this dissertation is the experimental, modelling and simulation of anaerobic
digestion processes from pilot bio-digesters. For this purpose, biochemical kinetic models were
utilized together with corresponding simulation software; DYNOCHEM. By application of the
anaerobic digestion (AD), different parameters have been investigated and simulated including
adjustments of the process model and corresponding modifications. To validate the process model,
the modelled data was compared with experimental monitored laboratory results. Bio-chemical
kinetics modelling was applied as a systematic tool in order to support the process design and
optimization of a demonstration of the biogas processes which constitutes the main scientific
framework and background of this dissertation. Monitored laboratory-scale biogas production data
were used for parameter calibration in order to predict plant performance. The calibration focused
on the influent characterization of both substrates and on selection of kinetic of the coefficients in
order to generate a uniform set of parameters which are applicable for the simulation of codigestion.
In this study, it was observed that the experiment work under laboratory scale using
conventional bio-methane potential (BMP) analyzers under mesophilic optimum temperature of
35 oC and 37 oC, and pH of 7 for co-digestion of organic fraction of municipal solid waste
(OFMSW) with cow dung and manure with grass clippings. The substrate characterization
moisture content ranged from 60-95%, volatile content 55-95%, total solid 10-90% and carbon to
nitrogen ratio 16-20 for manure and 5-15 for OFMSW. All trace elements concentration were
below the threshold of 32 mg/l that leads to inhibition of micro-organisms activity. The rate of
conversion increased with retention time. According to the findings, 54-62% of methane
composition was evaluated. The kinetics constant evaluated ranged from 0.009-0.35 d-1 and
coefficient of determination (R2) ranged from 0.9989-0.9998. The Michaelis-Menten and Monod
models provided goodness of fit of 0.9997 with confidential level of 95%. The simulations
confirmed that the rate of conversion increased as temperature increases and conversion of
reactants increased with retention time, until an equilibrium state was reached. The AD process
modelling using DYNOCHEM was successfully modified and implemented to account for
unsteady operation which is generally the case of full-scale reactor by developed methodology.
M.Tech. (Chemical Engineering)