- Control bed depths to between 2 - 3 feet by adjusting recycle rates
- Hydraulic residence time in clarifier 2 - 4 hours
- Warm temperatures increase denitrification (high metabolic activity) so problem is usually more pronounced in summer months
- Use a water spray to degas the floating solids - you will see the bubbles breakout and the sludge sink
Denitrification in secondary clarifiers
Denitrifcation happens when bacteria begin to use nitrate and nitrite as an alternative electron acceptor. This a complex way to say that the bacteria are using the oxygen in nitrate and nitrite, leaving nitrogen gas. If you get denitrification in a treatment basin, it is a good sign and often required for facilities with nitrite/nitrate discharge limits. If you have denitrification in a secondary clarifier, you can have floating solids with TSS carryover into the effluent. So what can you do to prevent denitrification in secondary clarifiers:
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Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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