Related Experiment Video
Updated: Jul 3, 2026
08:13
A Novel Bioreactor for High Density Cultivation of Diverse Microbial Communities
Published on: December 25, 2015
Activated sludge process performance using a multistage tower aeration tank
1Department of Sanitary and Environmental Engineering, Faculty of Engineering, Hokkaido University, Kita-ku, Sapporo, Japan.
Biotechnology and Bioengineering
|July 1, 1993
Summary
The vertical multistage tower aeration system offers superior purification efficiency and better sludge management compared to completely mixed systems. This advanced activated sludge treatment is ideal for optimizing wastewater treatment processes.
Area of Science:
- Environmental Engineering
- Biotechnology
- Wastewater Treatment
Background:
- Conventional activated sludge systems face challenges in optimizing purification efficiency and sludge characteristics.
- Understanding the hydrodynamics and kinetics of different aeration tank designs is crucial for effective wastewater treatment.
Purpose of the Study:
- To experimentally and theoretically compare vertical multistage tower aeration tanks with completely mixed systems.
- To evaluate advantages in purification efficiency, sludge settleability, and excess sludge production.
Main Methods:
- Experimental comparison of two aeration systems under various organic loadings.
- Theoretical analysis using an axial dispersion model and growth kinetics.
- Investigation of rapid uptake processes like biosorption and biodegradation.
Main Results:
- The multistage tower system demonstrated higher purification efficiency across all organic loading conditions.
- Significant advantages were observed in sludge settleability and reduced excess sludge production.
- The enhanced performance was quantitatively explained by the axial dispersion model and rapid kinetic processes.
Conclusions:
- Vertical multistage tower aeration tanks are advantageous over completely mixed systems for wastewater treatment.
- The system's design promotes better purification, sludge settling, and minimizes sludge yield.
- Kinetic modeling confirms the benefits of partial fluid mixing in activated sludge processes.
Related Concept Videos
01:29Bioreactor Design and Operational System
Bioreactors are engineered vessels designed to cultivate microorganisms under controlled conditions for industrial bioprocessing. They maintain sterility and allow precise regulation of pH, temperature, oxygen, and nutrient levels to optimize microbial growth and metabolite production. Bioreactors range from small laboratory units of 1 liter to industrial systems holding up to 500,000 liters, though only about 75% of their volume is actively used for fermentation. The remaining headspace...
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...
01:30Biological Treatment of Effluent and Waste Water
Biological wastewater treatment relies on the metabolic activity of microorganisms to remove pollutants from sewage. In modern treatment systems, this process is organized into sequential stages that progressively reduce solid material, dissolved organic matter, and microbial contamination. Each stage plays a distinct role in improving water quality and preparing the effluent for safe discharge or reuse.Primary and Secondary TreatmentPrimary treatment is a physical process that removes large...
01:30Microbial Wastewater Treatment
Microbial communities in aquatic ecosystems play a key role in the natural breakdown of contaminants introduced through domestic and industrial effluents. Acting as biological catalysts, these microbes change and mineralize a wide range of organic and inorganic pollutants under different redox conditions.In oxygen-rich surface waters, aerobic heterotrophs lead organic matter breakdown, using oxygen as the terminal electron acceptor to efficiently oxidize substrates to carbon dioxide and water.
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...
01:28Bioreactor Controls-I
Maintaining optimal conditions within fermenters is essential for maximizing microbial productivity and ensuring process efficiency. This lesson focuses on key parameters—temperature, foam, pH, carbon dioxide, oxygen, and pressure—and their precise measurement and control strategies in fermentation systems.Temperature ControlTemperature regulation is critical due to the exothermic nature of many fermentation processes. In small laboratory fermenters, temperature is commonly monitored using...