Simultaneous nitrogen and phosphorus removal through an integrated partial-denitrification/anammox process in a...

Area of Science:

• Environmental Engineering
• Microbiology
• Wastewater Treatment

Background:

• Conventional wastewater treatment struggles with simultaneous nitrogen and phosphorus removal.
• Phosphate recovery is crucial for resource management and preventing eutrophication.

Purpose of the Study:

• To evaluate an integrated partial-denitrification/anaerobic ammonia oxidation (PD/A) process for enhanced nitrogen removal and phosphate recovery in mainstream sewage.
• To assess the efficiency and microbial community of the PD/A process in an up-flow anaerobic fixed-bed reactor (UAFB).

Main Methods:

• Startup of a UAFB reactor with anammox sludge and controlled influent.
• Monitoring nutrient removal efficiencies (nitrogen, phosphorus, COD) over 189 days.
• Microbiological analysis using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and microbial community profiling.

Main Results:

• Achieved 82% phosphorus removal efficiency at an influent concentration of 12.0 mg/L.
• Stable removal of COD, nitrogen, and phosphorus at a COD/NO3--N ratio of 3.5.
• Identified hydroxyapatite as the main crystal in the biofilm and key microbial players including AnAOB (Ca. Brocadia, Ca. Kuenenia, Ca. Jettenia) and denitrifying/phosphorus-accumulating bacteria.

Conclusions:

• The integrated PD/A process is a viable option for simultaneous nutrient removal and phosphate recovery in sewage treatment.
• The UAFB reactor configuration effectively supports the PD/A process, with key microbial activities concentrated at the reactor bottom.
• Understanding the microbial community is essential for optimizing advanced nutrient removal processes.