Modeling and simulation of lab-scale anaerobic co-digestion of MEA waste

Anaerobic digestion model No.1 (ADM1) was applied and expanded in this study to model and simulate anaerobic digestion (AD) of an industrial carbon capture reclaimer MEA (monoethanolamine) waste (MEAw) together with easily degradable organics. The general structure of ADM1 was not changed except for introducing state variables of MEA and complex organics (CO) in the waste and biochemical reactions of MEA uptake and CO hydrolysis in the model ADM1 MEAw. Experimental batch test results were used for calibrating kinetics variables. The obtained kinetics were employed in the ADM1 MEAw to simulate semi-continuously fed experimental test for 486 days at room temperature (22 ± 2 C). The validation results show that the ADM1 MEAw was able to predict the process performance with reasonable accuracy, including process pH, biogas generation and inorganic nitrogen concentrations, for a wide range of feed scenarios. Free ammonia inhibition, was observed to be the main inhibitory effects on acetoclastic methanogenesis, leading to volatile fatty acids (VFA) accumulation at high loads. Inhibition assumed to be caused by potentially toxic constituents of MEAw appears to be much less important than ammonia, suggesting that such constituents were broken down by AD.