The full picture for costs and energy recovery: liquid and solids treatment and what goes on in between
Dold, P. and Jones, R., Envirosim Associates, Canada
(free)
A whole plant simulation model provides a basis for objective analysis of the interactions between performance of treatment units (biological, physical and separation), and the impact on potential energy consumption and recovery and carbon footprint. The focus of this paper is the analysis of anaerobic digester performance, including volatile solids destruction and the potential for biogas production. The paper demonstrates that the potential digester VS destruction and biogas production are strongly influenced by (a) the raw influent unbiodegradable particulate COD fraction (Fup), and (b) PST removal efficiency. For a given PST performance, activated sludge operating SRT has a relatively minor impact on digester performance per unit load to the digester. However, operating at a very short SRT results in a higher load to the digester, with increased gas production. The analysis in the paper is based on COD as the underlying variable because this allows the different components making up the volatile solids to be tracked separately. An important factor is that the COD approach facilitates tracking the unbiodegradable particulate components; these essentially set the performance limits.
Keywords: Anaerobic digestion, process simulation, whole-plant modelling, raw influent characterization, solids train optimization
