Tennessee Wastewater Operator Practice Exam

What happens to phosphorous that is removed from an Enhanced Biological Phosphorous Removal (EBPR) process?

1. It is released back into the water

2. It is sequestered in the Waste Activated Sludge (WAS)

3. It is used by other microorganisms

4. It is converted to soluble phosphates

The correct answer is: It is sequestered in the Waste Activated Sludge (WAS)

In the Enhanced Biological Phosphorus Removal (EBPR) process, phosphorus is primarily removed by specialized microorganisms known as polyphosphate accumulating organisms (PAOs). These organisms take up excess phosphorus from the wastewater and store it within their cells in the form of polyphosphate. When the process is functioning effectively, a significant portion of the phosphorus removed from the wastewater through EBPR becomes sequestered in the Waste Activated Sludge (WAS) along with the PAOs. This is an important aspect of EBPR, as it helps in the long-term removal of phosphorus from the treatment system. When the sludge is later removed from the system, the phosphorus is effectively taken out of the water, which reduces the nutrient load in the effluent and minimizes the risk of eutrophication in receiving waters. The other potential outcomes of phosphorus during wastewater treatment processes are not applicable in this context. For instance, the release back into the water, utilization by other microorganisms, or conversion to soluble phosphates do not occur to the same extent within the EBPR framework, as the goal is specifically to capture and sequester phosphorus in the sludge instead.