Related Experiment Video
Updated: Jun 8, 2026
11:31
Continuously-stirred Anaerobic Digester to Convert Organic Wastes into Biogas: System Setup and Basic Operation
Published on: July 13, 2012
Numerical simulation of mechanical mixing in high solid anaerobic digester.
Liang Yu1, Jingwei Ma, Shulin Chen
1Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA.
Bioresource Technology
|October 19, 2010
Summary
Computational fluid dynamics simulations reveal helical ribbon mixers show great potential for high solids anaerobic digesters (HSAD). This study quantifies mixing performance and power consumption for efficient HSAD operation.
Area of Science:
- Engineering
- Environmental Science
- Biotechnology
Background:
- Effective mixing is crucial for high solids anaerobic digestion (HSAD) efficiency.
- Traditional impellers may face challenges in high-solids environments.
- Understanding fluid dynamics is key to optimizing digester performance.
Purpose of the Study:
- To investigate and compare the mixing performance of A-310 impeller and helical ribbon mixers in HSAD.
- To develop and validate a mathematical model for HSAD flow fields.
- To determine optimal operating parameters for power consumption and mixing in HSAD.
Main Methods:
- Computational fluid dynamics (CFD) simulations were used to model flow fields.
- A mathematical model was constructed and validated against experimental data for the A-310 impeller.
- Simulations were conducted for digesters with 5% and 10% total solids (TS).
Main Results:
- The CFD model showed good agreement with experimental data for the A-310 impeller.
- A systematic comparison of power number, flow number, and Reynolds number was performed.
- Helical ribbon mixers demonstrated significant potential for mixing in HSAD.
Conclusions:
- Helical ribbon mixers are a promising technology for improving mixing in high solids anaerobic digesters.
- The study provides quantitative data on minimum power consumption and shear rate effects in HSAD.
- CFD modeling serves as a valuable tool for optimizing HSAD design and operation.
Related Concept Videos
01:18Bioreactor Controls-II
In aerobic fermentations, oxygen is vital for microbial growth and metabolite production. Since air comprises only about 20% oxygen and the gas is poorly soluble in water—just 9 ppm at 20°C—supplying sufficient oxygen becomes a critical challenge, especially in high-demand processes like yeast growth or citric acid production. Even a fully saturated broth may offer only a few seconds of oxygen availability.To address this, sterile or scrubbed air is introduced into the fermentor via a sparger...
01:14Scale-Up Processes
The scale-up of microbial fermentation processes is essential in industrial biotechnology, allowing the transition from laboratory-scale experiments to commercial-scale production while aiming to maintain product yield and quality. This process requires meticulous adjustment of equipment design, process parameters, and contamination control strategies to accommodate increasing culture volumes.At the laboratory scale, cultures are typically maintained in 1 to 10-liter glass or autoclavable...