Saving phosphorus removal at the Henderson NV plant

Area of Science:

• Environmental Science
• Environmental Engineering
• Microbiology

Background:

• Biological phosphorus removal (BPR) is a well-researched wastewater treatment process.
• Volatile fatty acids (VFA) are considered essential for effective BPR, typically requiring a designated anaerobic zone.
• BPR has been observed in facilities lacking a dedicated anaerobic zone, challenging existing design principles.

Purpose of the Study:

• To investigate the mechanism of BPR in the absence of a conventional anaerobic zone.
• To propose a theory explaining BPR under non-standard conditions.
• To address VFA shortages in wastewater influent and optimize phosphorus removal.

Main Methods:

• Case studies of plants exhibiting BPR without designated anaerobic zones were examined.
• A theory was developed to explain observed BPR phenomena.
• Mixed liquor fermentation was implemented in an anaerobic zone at the Henderson NV plant to address VFA deficiency.

Main Results:

• Biological phosphorus removal was achieved even in systems without a dedicated anaerobic zone.
• Implementing mixed liquor fermentation in an anaerobic zone successfully reduced phosphorus to very low levels.
• The study provided practical solutions for VFA-deficient influent, enhancing phosphorus removal efficiency.

Conclusions:

• The necessity of a designated anaerobic zone for BPR may be reconsidered.
• In-situ fermentation of mixed liquor can be an effective strategy to enhance BPR, especially when VFA is limited.
• Further research into the mechanisms and modeling of BPR under various conditions is warranted.