Video 1 of 4: Enhanced Biological Phosphorus Removal (EBPR)

Summary

David Mullins, a process engineer at Enviromix, introduces the first video in a four-part series on optimizing biological phosphorus removal (EBPR) in wastewater recovery facilities. He explains how phosphorus accumulating organisms (PAOs) are key to the EBPR process, accumulating phosphorus in alternating anaerobic and aerobic environments. The process helps wastewater plants meet stringent regulatory phosphorus removal standards. Mullins highlights the importance of truly anaerobic environments and volatile fatty acids (VFAs) for the success of EBPR. In the next video, he will explore how VFA shortages can hinder the process and how fermentation can help produce more VFAs.

Takeaways

• 😀 Biological phosphorus removal (EBPR) is a process that helps wastewater recovery facilities meet regulatory phosphorus removal standards.
• 😀 Some facilities use chemicals for phosphorus removal, but EBPR relies on natural biological processes for more sustainable phosphorus management.
• 😀 Phosphorus accumulating organisms (PAOs) are key to the EBPR process, as they naturally accumulate phosphorus from the wastewater.
• 😀 Activated sludge, the microbial community in the treatment plant, thrives in both aerobic and anoxic environments, with PAOs gaining a competitive advantage in the presence of alternating anaerobic and aerobic conditions.
• 😀 During the anaerobic phase, PAOs consume carbon through volatile fatty acids (VFAs) and release phosphorus into the wastewater, which initially seems counterproductive to phosphorus removal.
• 😀 The anaerobic environment is crucial for PAOs, as it provides a competitive edge over other microbes that require oxygen for carbon consumption.
• 😀 A truly anaerobic environment means no free or chemically bound oxygen (such as nitrate) is present, and the ORP (Oxidation-Reduction Potential) should be below negative 200 millivolts.
• 😀 In the aerobic phase, PAOs use carbon reserves to absorb phosphorus from the wastewater, resulting in a net removal of soluble phosphorus.
• 😀 After passing through the aerobic zone, PAOs leave the mainstream process through waste activated sludge, which reduces phosphorus concentrations in the treated water.
• 😀 Some plants may struggle with effective phosphorus removal despite having anaerobic selectors, which could be due to a shortage of VFAs, a topic to be addressed in the next video.

Q & A

What is Enhanced Biological Phosphorus Removal (EBPR)?

EBPR is a biological process used in wastewater treatment to remove phosphorus, relying on naturally occurring organisms called phosphorus accumulating organisms (PAOs) to accumulate and remove phosphorus as they travel through the treatment plant.

Why is phosphorus removal important in wastewater treatment?

Phosphorus removal is critical to meet stringent regulatory requirements and to prevent environmental issues such as eutrophication, which can harm aquatic ecosystems by promoting excessive algae growth.

What role do Phosphorus Accumulating Organisms (PAOs) play in EBPR?

PAOs are the key microorganisms in EBPR. They accumulate phosphorus in their cells and help remove it from wastewater. They are specially adapted to thrive in environments where phosphorus levels fluctuate.

How do PAOs accumulate phosphorus in the EBPR process?

PAOs accumulate phosphorus by consuming volatile fatty acids (VFAs) in an anaerobic environment and storing the phosphorus within their cells. The phosphorus is then released in the anaerobic phase and taken up again in the aerobic phase, leading to net phosphorus removal.

Why is an anaerobic selector important in the EBPR process?

The anaerobic selector provides a truly anaerobic environment where PAOs can outcompete other microorganisms, releasing stored phosphorus and enabling them to store carbon for growth, which is critical for effective phosphorus removal in subsequent aerobic conditions.

What defines a 'truly anaerobic environment' in wastewater treatment?

A truly anaerobic environment is one where there is no free oxygen or chemically bound oxygen (such as nitrate), and when measuring the Oxidation-Reduction Potential (ORP), it should remain below negative 200 millivolts.

How do PAOs function in the aerobic phase of EBPR?

In the aerobic phase, PAOs use their stored carbon reserves as an energy source to uptake phosphorus and grow, leading to a net removal of phosphorus from the wastewater.

What happens to the PAOs after the aerobic phase in EBPR?

After the aerobic phase, PAOs exit the mainstream process through waste activated sludge, leaving behind treated water with significantly lower phosphorus concentrations.

What challenges can occur with anaerobic selectors in phosphorus removal?

Even with anaerobic selectors, some wastewater treatment plants struggle with effective phosphorus removal due to factors such as insufficient volatile fatty acids (VFAs) or improper anaerobic conditions, which hinder PAOs from flourishing.

What is the next topic that will be covered in the series of videos?

The next video will address how a shortage of volatile fatty acids (VFAs) can limit EBPR and explore how wastewater plants can produce additional VFAs using a process called fermentation.