Modeling of oxygen uptake rate evolution in pig manure–wheat straw aerobic composting process

• A revised oxygen uptake rate model for pig manure-based composting was established.
• Sensitivity analyses were performed to simulate different composting processes.
• The specific growth rate constant of the composting mixture is 0.42 h−1.
• Enhanced aeration in thermophilic phase is suggested for soluble rich substrate.
• Reducing insoluble substrate and particle size are good ways to improve composting.

A revised oxygen uptake rate model that considers the specific characteristics of the substrate and the temperature dependence of microbial growth for pig manure–wheat straw aerobic composting was established. The model validation results showed good agreement with experimental data. The model’s accuracy, in terms of a lower relative error and fewer deviations of the oxygen uptake rate, was improved, but the oxidation of the remaining carbon requires further study. Sensitivity analyses were performed to simulate different composting processes and to explore potential engineering applications to the improvement of composting. The specific growth rate constant of the composting mixture was 0.42 h−1. Enhanced aeration in the thermophilic phase is suggested for a soluble-rich substrate. Reducing insoluble substrate will help shorten composting period and improve the product’s stability. The smaller the particle size, the better the composting efficiency when air permeability is guaranteed. The optimal ambient temperature of the compost was 21–35 °C. These findings provide a theoretical basis that can inform the design of an economical operation strategy for aerobic composting.

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