An integrated physical and biological model for anaerobic lagoons

• Published in: Bioresource technology 2011-04, Vol.102 (8), p.5032-5038
• Main Authors: Wu, Binxin, Chen, Zhenbin
• Format: Article
• Language: English
• Subjects: Anaerobic lagoon; Anaerobiosis; Biological; Biological and medical sciences; Biological treatment of waters; Biotechnology; BOD reduction; Computational fluid dynamics; Computer simulation; Environment and pollution; Fluid flow; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; Lagoons; Mathematical models; Methane; Methane - metabolism; Methane production; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Models, Biological; Reduction; Resident time; Temperature; Turbulent flow; Water Movements; Water Pollutants - metabolism
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2011.01.076

A computational fluid dynamics (CFD) model that integrates physical and biological processes for anaerobic lagoons is presented. In the model development, turbulence is represented using a transition k–ω model, heat conduction and solar radiation are included in the thermal model, biological oxygen demand (BOD) reduction is characterized by first-order kinetics, and methane yield rate is expressed as a linear function of temperature. A test of the model applicability is conducted in a covered lagoon digester operated under tropical climate conditions. The commercial CFD software, ANSYS-Fluent, is employed to solve the integrated model. The simulation procedures include solving fluid flow and heat transfer, predicting local resident time based on the converged flow fields, and calculating the BOD reduction and methane production. The simulated results show that monthly methane production varies insignificantly, but the time to achieve a 99% BOD reduction in January is much longer than that in July.