Water Environment Federation (WEF)

Ineterfacing the IWA Anaerobic Digestion Model no.1 (ADM1) with Manure and Solid Waste Characteristics

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Courtesy of Courtesy of Water Environment Federation (WEF)

An interface to ADM1 was developed to estimate the solid waste composition from its practical characteristics. The interface was based on COD, elemental, charge and covalent bond balances to conceal any error in collected characteristics from different sources. The interface was validated by reported characteristics of manure and food wastes and determined with relevant accuracy the wastes’ composition of carbohydrates, proteins and lipids. The benefit from the interface application with ADM1 is illustrated through virtual case studies of co-digestion and comparison of existing high solids digester designs for given solid waste characteristics. Thus the developed interface serves as a tool for early and efficient decision on technology selection of high solids digestion.

Substrate composition information is important for simulating and optimizing anaerobic digestion processes and reactors. Substrate composition determines the process pathways and influences the biofilm development in high rate anaerobic reactors such as Fluidized Beds (FB) and Upflow Anaerobic Sludge Bed reactors (UASB) (Garcia-Encina and Hidalgo, 2005). The substrate composition is even more important and considered as the bottle neck for high solids digestion due to the importance of the hydrolysis step (Hartmann and Ahring, 2006; Johansen and Bakke, 2006). Also, hydrolysis rates differs significantly (Mata-Alvarez, 2000) for particulate components, e.g. carbohydrates, proteins and lipids. In 2002, the International Water Association (IWA) Task Group for Mathematical Modeling of Anaerobic Digestion Processes developed the Structured Anaerobic Digestion Model no.1 (ADM1) to describe the different process pathways in detail. The model is structured with disintegration and hydrolysis, acidogenesis, acetogenesis and methanogenesis steps. According to the ADM1 technical report (Batstone et al., 2002), disintegration is mainly included to describe degradation of composite particulate material with lumped characteristics (such as primary or waste-activated sludge), while the hydrolysis steps are to describe well defined, relatively pure substrates (such as cellulose, starch, lipids and protein feeds). Considering the fact that it is neither possible to fix the waste to one lumped characteristic nor practical to characterize it as pure substrates, this paper presents an interface that is developed to dynamically calculate the ADM1 input from practical...

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