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Aeration Techniques at SAFL
Aeration Measurements, Water Quality Models
SAFL researchers are experts in the measurement of aeration ( and desorption) and in research in air-water exchange of oxygen, nitrogen and volatile organic chemicals. Our expertise includes natural and artificial tracer measurement of oxygen uptake, nitrogen super-saturation at spillways and weirs, and tracer measurement of stream and lake surface reaeration coefficients using sulfurhexaflouride, as well as time of travel measurements. The site-specific measurements provided by SAFL are often critical to development of accurate stream water quality models.
Aeration at Hydraulic Structures
Through its hydropower and water quality research, SAFL has developed expertise in testing, analysis and modeling of aeration at hydraulic structures. Our experience comprises weirs for water quality improvement, spillway discharge for improvement of reservoir releases, nitrogen supersaturation at high spillways, turbine discharge selective withdrawal, and turbine venting for improving oxygen.
Aeration Testing and Development
Aerators create an aerated refuge for fish without upsetting weak winter stratification, thus limiting oxygen demand on the system. SAFL engineers conduct testing of aerators according to ASCE standards in its volumetric tanks and at project sites. SAFL has also helped develop three aerators: 1) a hollow fiber membrane design which achieves transfer without bubble formation; 2) a stovepipe aerator, which provides more control and higher efficiency than porous stone diffusers, and 3) a withdrawal and delivery system to allow winter lake aeration without causing open water. |
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Research Projects
Ice-preserving Winter Aeration
Winter aeration is often required to prevent fish kill in ice covered lakes, but can cause dangerous open water conditions. SAFL has designed, constructed and successfully tested a withdrawal and delivery system to allow winter lake aeration without causing open water. Water is gently withrawn, aerated on shore, and reintroduced by a diffuser. The aerator creates an aerated refuge for fish without upsetting weak winter stratification, thus limiting oxygen demand on the system. |
Selected Applications
- ASCE Standard testing of aerators (field and lab)
- Aeration at hydraulic structures
- Dissolved gas modeling
- Oxygen and tracer measurement of reaeration
- Time of travel (dye) studies
- Aeration design
- Winter fish protection
- Air-water flow mixtures
- Wastewater treatment via aeration
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Wastewater Treatment via Aeration
Aeration is an important step in the treatment of wastewater. Through aeration, oxygen is introduced into the wastewater. SAFL has been involved in both the design and testing of various methods of aeration, such as using porous membranes with pure oxygen under pressure, compressed air through perforated plates with very small perforation, and large fountain types, in which air is entrained with the fountain's water flow. A significant portion of the cost of wastewater treatment is in aeration expense. By aiding the design and testing of more efficient aerations, SAFL has directly worked to reduce treatment costs and increased the effectiveness of municipal wastewater treatment processes.
Aerator efficiency testing
SAFL performed dissolved oxygen transfer efficiency testing for a large manufacturer of asperator-type aerators. The tests were performed using the ASCE standard for monitoring DO transfer in clean water. SAFL has extensive testing experience with fountain, jet, and fine bubble aeration systems. With our volumetric tanks we can accommodate the testing of very large aeration systems. |
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