Volume 19 Part 1 Article 30: A comprehensive mathematical model to simulate the composting process for production of substrate for Agaricus bisporus

Volume 19 Part 1 Article 30
Year 2016
Title: A comprehensive mathematical model to simulate the composting process for production of substrate for Agaricus bisporus
Author: Ana Ribeiro and Peter J.T. Verheijen

The use of mathematical models to simulate chemical and biological processes can help industries to gain a better understanding of their processes and improving them. For a complex process such as composting, where the activities of several microbiological communities change the biochemistry of the surrounding environment, a mathematical model helps to identify which of the mechanisms have the highest impact on the process and on the final characteristics of the compost. A simulation based on the mathematical model predicts the outcome of design changes to the process, and accelerates research and development efforts.

A comprehensive mathematical model was developed, gathering state-of-the-art knowledge about the microbiological, chemical and physical mechanisms taking place in composting. The aim of the model is to simulate the trends in temperature, compaction and composition (in water, dry matter, carbohydrates and organic nitrogen) of compost piles in tunnels, throughout three phases of the process for A. bisporus substrate production.

In the model is included the growth and death kinetics of important microbiological groups under the limitation of moisture content, temperature and substrate availability. Heat and mass transport between the compost and the gas phase, compaction and porosity changes throughout time and height of the pile are modelled as well. The aeration scheme is also included in the simulation, as it plays an important role in controlling the process in tunnels.

The model developed can successfully predict the temperature trends of the process as it happens at CNC Grondstoffen. It brought important insights to the process, such as the importance of the different microbiological communities throughout time and across the height of the composting pile. Because the aeration control is included in the simulations, different flowrates, temperatures and composition could be simulated and their effect on the characteristics of the compost could be estimated. We are currently expanding the model to include other microbiological communities and proceed to experimentally validate it.

The presented model systematically aggregates the current knowledge for the production of substrate for A. bisporus, and can be used as a tool to synthesize and study process design improvements.

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