Nutrient Removal · Biological Phosphorus Removal
What Are Volatile Fatty Acids?
Volatile fatty acids, or VFAs, are short-chain organic acids that PAOs can take up readily in the anaerobic zone. Acetate and propionate are common examples. They may already be present in influent or may form when wastewater or primary sludge ferments.
Total BOD or chemical oxygen demand does not show how much usable VFA reaches the PAOs. A plant can receive enough total carbon but still have weak EBPR if the carbon arrives in a form or location that PAOs cannot use quickly.
Some facilities ferment primary sludge or add an approved carbon source to support EBPR. These systems require plant-specific control. Follow the process plan, plant procedures, and SDS. Watch odors, recycle effects, chemical feed, and the response in phosphate profiles.
Influent fermentation can change with temperature and sewer conditions. This helps explain why EBPR carbon supply may vary by season.
Key point: PAOs need the right carbon in the anaerobic zone at the right time.
Keep learning
Nutrient Removal: Nitrogen and Phosphorus for Wastewater Operators
This page comes from the course. It covers nitrification, denitrification, biological and chemical phosphorus removal, monitoring, return loads and permit limits, one step at a time, with short knowledge checks and a certificate of completion.
Take the course