Optimization of advanced biogas production via the DiCOM bioprocess utilizing the biogas test plant BTP2: Insights from multifactorial analysis

Abstract

This study introduces an innovative optimization of the DiCOM bioprocess, which integrates aerobic composting and anaerobic digestion, utilizing the Biogas Test Plant BTP2 configured as a continuous stirred-tank reactor (CSTR). The research seeks to enhance biogas production from sewage sludge by examining the effects of key operational parameters, including temperature, pH, inoculum-to-substrate ratio, and stirrer speed. This investigation is pioneering in its use of a DiCOM-CSTR configuration, distinguishing it from previous studies that focused on fixed-bed or sequential systems. This approach facilitates continuous operation and enhances process control. A multifactorial experimental design was employed, utilizing Box-Behnken Design (BBD) and Response Surface Methodology (RSM), along with Principal Component Analysis (PCA), to evaluate the combined impacts of critical parameters such as temperature, pH, inoculum-to-substrate ratio (ISR), and stirrer speed. Under optimized conditions, a thermophilic temperature of 65 °C, neutral pH (7.0–7.5), ISR of 0.63, and controlled stirring speed of 100 rpm contributed to achieving a methane yield of up to 64.2 % and hydrogen sulfide concentrations as low as 3.9 ppm. The results surpass previously reported values, confirming the effectiveness of the proposed configuration and methodological approach. The integrated PCA-RSM framework provided enhanced multivariate insight into parameter interactions and process dynamics. Future studies should deepen the understanding of microbial community dynamics, assess the long-term operational stability of the DiCOM process, and evaluate its adaptability across diverse organic waste streams. This study not only advances the design and optimization of DiCOM systems but also offers a scalable approach for sustainable energy recovery from organic waste.