Video 2 of 4: Fermentation for EBPR

Summary

In this video, David Mullins, a process engineer at Enviromix, explains how fermentation can optimize biological phosphorus removal (EBPR) in wastewater recovery facilities. He details how volatile fatty acids (VFA), produced through anaerobic fermentation, are crucial for enhancing phosphorus removal efficiency. By creating a deeply negative ORP environment and promoting the accumulation of sludge in the anaerobic zone, wastewater facilities can boost VFA production and phosphorus release from PAOs. The video emphasizes the importance of balancing fermentation and mixing strategies to maximize phosphorus removal.

Takeaways

• 😀 The effectiveness of biological phosphorus removal (EBPR) is determined by influent wastewater characteristics, especially the amount of volatile fatty acids (VFA) relative to phosphorus to be removed.
• 😀 Facilities with insufficient VFA can increase VFA production through anaerobic fermentation processes.
• 😀 VFA is created through hydrolysis and fermentation, where complex organic matter is broken down into soluble organics such as sugars and acids.
• 😀 Facultative bacteria play a key role in converting soluble organics into VFA, which is essential for phosphorus removal.
• 😀 In-line fermentation, or fermenting within an anaerobic selector, is a method used to increase VFA production within the mainstream wastewater treatment process.
• 😀 To optimize fermentation in the anaerobic zone, it is critical to ensure a deeply negative oxygen reduction potential (ORP) environment.
• 😀 Allowing mixed liquor to settle and accumulate helps create a sludge blanket, which increases the anaerobic mass fraction and solid retention time (SRT).
• 😀 The fermentation layer hydrolyzes and ferments carbon over time, producing VFA, which is essential for phosphorus release in PAOs.
• 😀 Intermittent mixing of the anaerobic zone suspends the fermentation blanket, discourages methanogenic bacteria from consuming VFA, and replenishes the blanket with organic matter for continued VFA production.
• 😀 The balance between VFA production (without mixing) and VFA transport to phosphorus-accumulating organisms (PAOs) during mixing is crucial for effective phosphorus removal.
• 😀 For more insights on optimizing VFA transport and mixing strategies, viewers are encouraged to check out the next video in the series.

Q & A

What is the main focus of this video?

The video focuses on explaining the dynamics of fermentation and how it can boost biological phosphorus removal (EBPR) in wastewater treatment facilities.

What is biological phosphorus removal (EBPR), and how is it related to fermentation?

Biological phosphorus removal (EBPR) is a process used in wastewater treatment to remove phosphorus. Fermentation plays a role in EBPR by producing volatile fatty acids (VFA), which are consumed by phosphorus-accumulating organisms (PAOs) to release stored phosphorus and support their growth.

How does fermentation help in biological phosphorus removal?

Fermentation helps by creating volatile fatty acids (VFA) through the breakdown of complex organic matter, providing PAOs with the necessary carbon source to release stored phosphorus and grow.

What factors determine the success of EBPR?

The success of EBPR is primarily determined by influent wastewater characteristics, specifically the amount of volatile fatty acids (VFA) in proportion to the amount of phosphorus that needs to be removed.

What can facilities do if they have insufficient influent VFA?

Facilities with insufficient influent VFA can encourage additional VFA production through anaerobic fermentation, which helps provide the necessary carbon source for PAOs.

What are the processes involved in VFA production?

VFA is produced through hydrolysis and fermentation. During hydrolysis, complex organic matter like carbohydrates, proteins, and fats are broken down by enzymes into soluble organics such as sugars and acids. Facultative bacteria then convert these soluble organics into VFA.

What is in-line fermentation, and why is it important?

In-line fermentation refers to fermenting wastewater within the anaerobic selector, also known as the anaerobic zone, during the mainstream wastewater treatment process. It is important because it helps produce VFA, which are necessary for biological phosphorus removal.

What are the key operational conditions required to encourage fermentation in the anaerobic zone?

To encourage fermentation in the anaerobic zone, three key conditions must be met: 1) ensuring a deeply negative oxidation-reduction potential (ORP) environment, 2) allowing mixed liquor to settle and accumulate, and 3) increasing the anaerobic mass fraction and solids retention time (SRT).

How does the settling of mixed liquor in the anaerobic zone contribute to fermentation?

When mixing is turned off, the biomass settles, forming a sludge blanket that accumulates at the bottom of the tank. This process increases the anaerobic mass fraction and solids retention time (SRT), which enhances the fermentation process and leads to the production of more VFA.

Why is mixing intermittently applied in the anaerobic zone?

Mixing is intermittently applied to the anaerobic zone for two reasons: 1) to discourage methanogenic activity, which would consume the VFA, and 2) to recharge the sludge blanket with organic matter, supporting further VFA production.

What is the importance of balancing VFA production and movement in the anaerobic zone?

The balance between VFA production (without mixing) and the movement of VFA to PAOs (with mixing) is critical for optimizing the phosphorus removal process. Too much mixing can reduce VFA concentration, while insufficient mixing can limit the transport of VFA to PAOs.

What should viewers do to learn more about VFA transport and mixing strategies?

To learn more about VFA transport and the importance of dialing in the right mixing strategy, viewers are encouraged to watch the next video in the series.