Denitrification process and suspended solids separation in deep-bed two-media down-flow filters

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Microbial Ecology

Background:

• Denitrification is crucial for removing nitrogen pollutants from wastewater.
• Simultaneous suspended solids separation and denitrification in filters offer an efficient treatment approach.
• Understanding filter bed layer performance is key to optimizing nitrogen removal.

Purpose of the Study:

• To evaluate denitrification rates in pilot-scale filters with simultaneous suspended solids separation.
• To assess the robustness of the biofilm under different backwashing conditions.
• To optimize full-scale filter construction and operation based on pilot study findings.

Main Methods:

• Pilot-scale filter experiments were conducted to measure denitrification rates across different filter bed layers.
• Biofilm denitrification rates were analyzed for both unwashed and once-backwashed filter media.
• Full-scale filter performance was studied for further optimization of the denitrification process.

Main Results:

• Pilot filters showed high denitrification rates, particularly in the upper layer (79.0 g NOx-N m-3 h-1).
• The biofilm exhibited robustness, with only a slight decrease in denitrification rates after backwashing.
• Full-scale filters achieved significant nitrogen reduction, with middle layers showing optimal rates (27.8 g NOx-N m-3 h-1).

Conclusions:

• The studied denitrification process effectively removes nitrogen and separates suspended solids.
• Biofilm robustness ensures consistent performance even after backwashing.
• The findings provide a basis for optimizing full-scale wastewater treatment plant design and operation.