Modelling anaerobic co-digestion in Benchmark Simulation Model No. 2: Parameter estimation, substrate...

Area of Science:

• Environmental Engineering
• Biotechnology
• Wastewater Treatment

Background:

• Anaerobic co-digestion is gaining traction in wastewater treatment plants (WWTPs) to boost energy recovery and waste management.
• Plant-wide modeling is essential for evaluating co-substrate impacts on digester performance and overall WWTP operation.

Purpose of the Study:

• To develop and validate a modeling procedure for anaerobic co-digestion in WWTPs.
• To assess the influence of co-substrate composition (carbohydrates, proteins, lipids) on digester performance and stability.
• To investigate plant-wide effects of co-digestion, including methane production, operational costs, and nitrogen removal.

Main Methods:

• Developed a procedure to characterize and fractionate co-substrate Chemical Oxygen Demand (COD) for the Benchmark Simulation Model No. 2 (BSM2) and Anaerobic Digestion Model No. 1 (ADM1).
• Incorporated long-chain fatty acid inhibition into the ADM1 model for lipid-rich co-substrates.
• Conducted sensitivity analysis, principal component analysis (PCA), and validated the model with bio-methane potential (BMP) tests.

Main Results:

• Protein and lipid fractions significantly impact methane production and digester stability, with identified failure modes.
• The model demonstrated good predictive capability for carbohydrate-, protein-, and lipid-rich substrates.
• Plant-wide simulations confirmed increased methane production and reduced operational costs due to co-digestion.
• High protein loads can cause ammonia inhibition and overload nitrogen removal, while lipid-rich substrates are more tolerable.

Conclusions:

• The developed modeling approach effectively simulates anaerobic co-digestion in WWTPs.
• Optimizing co-substrate selection and dosage, particularly limiting protein content, is vital for efficient and stable anaerobic digestion.
• Co-digestion offers significant benefits for energy recovery and cost reduction in wastewater treatment.