Study of the use of ADM1 as a modeling platform for batch reactors used in the anaerobic processing of sugarcane vinasse

Author(s)

Pâmela Talita do Couto

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2021-05-21

Examining board members

Rogers Ribeiro; Eduardo Lucena Cavalcante de Amorim; Sérgio Francisco de Aquino; Eugenio Foresti; Karina Querne de Carvalho Passig

• Advisor: Rogers Ribeiro

Abstract

The modelling of biological reactors used in wastewater treatment has gained prominence in recent years due to the possibility of carrying out numerous simulations, in different scenarios, spending less financial and time resources compared to laboratory experiments. These mathematical models describe the physical, physicochemical processes and biological reactions that occur inside the reactors, enabling the simulation of substrate consumption, growth of microorganisms and the formation of new products over time. The model most widely used in the simulation of processes involving anaerobic digestion is the Anaerobic Digestion Model Number 1 (ADM1), which was structured for a continuous stirredtank reactor without cell recycling and for a complete anaerobic digestion process, since disintegration and hydrolysis of complex organic compounds to the production of methane and inorganic carbon. However, when describing the processing of specific wastewater or the application of other types of reactors, ADM1 must be changed to incorporate the particularities of each system. Therefore, in this work, ADM1 was modified to simulate the anaerobic processing of sugarcane vinasse in a methanogenic and an acidogenic reactor, both operated in batch regime. In both simulations, hypotheses were put forward based on the type of flow and on the metabolic pathways involved in the process. The methane production from sugar degradation was the only pathway considered for the AnSBBR (Anaerobic Sequencing Batch Biofilm Reactor). The routes of methane formation from long-chain fatty acids and amino acids were disregarded due to low concentrations or the absence of precursor compounds. Structural changes in ADM1 were made for the acidogenic batch reactor, with the elimination of some pathways and the incorporation of others. The absence of methanogenesis and acetogenesis in the acidogenic reactor was assumed and the following metabolic pathways were included: Lactate + Acetate → Butyrate + Hydrogen, Glycerol → Butyrate + Hydrogen, and Lactate → Acetate + Propionate, the latter one being incorporated into the model to describe the processing of vinasse in a batch reactor for concentrations below 30 kgCODm-3. The entire modeling process was performed using the Matlab R2015a software. The determination of free parameters was carried out with Box-Draper minimization method and Monte Carlo Markov Chain simulation method. In addition, these models were subjected to statistical tests to assess their reliability, such as the Geweke method and the Akaike Information Criterion. In order to validate the proposed metabolic pathways, samples of biomass from acidogenic reator were subjected to molecular biology techniques, which allowed the classification of microorganisms present in the system. Finally, it was concluded that the combination of all these techniques involved in the modeling process allowed a reliable description of the studied system. (AU)

• FAPESP's process: 16/21529-8 - Study of the use of ADM1 model as platform of modeling for different configurations of reactors used in the anaerobic treatment of vinasse
• Grantee: Pamela Talita do Couto
• Support Opportunities: Scholarships in Brazil - Doctorate