WM-W Submersible Nitrate Recirculation Pump

The Submersible Nitrate Recirculation Pump is built for wastewater treatment processes where nitrified mixed liquor must be continuously returned from the aerobic tank to the anoxic tank. This internal cycle supplies nitrate to denitrifying microorganisms, thereby reducing total nitrogen.

 

This product may also be called a Nitrate Recirculation Pump, Submersible Nitrification Liquid Return Pump, Nitrification Liquid Return Pump, Denitrification Recirculation Pump, or Submersible Pump for Denitrification, depending on the project design documents and local engineering terminology.

Because it uses our submersible mixer technology, the structure is compact, the flow rate is large, and the whole machine is made of stainless steel and protected by double mechanical seals, which greatly reduces the damage rate and maintenance costs. It is suitable for applications requiring low head and large circulation flow in wastewater treatment, water supply, and drainage projects.

The pump is installed underwater in the aerobic zone, internal return channel, or pump pit. During operation, the impeller pushes nitrified mixed liquor through a through-wall pipe or recirculation passage and sends it back to the anoxic zone.

In the anoxic zone, denitrifying bacteria use available carbon sources to convert nitrate nitrogen into nitrogen gas. This process supports total nitrogen removal in A/O, A2/O, oxidation ditch, MBR, and MBBR treatment systems.

Because nitrate liquor return usually requires a large flow rate but only a small lifting height, this pump is designed for low-head and high-flow operation. The blades can be adjusted as needed, and VFD control can be used where the plant needs flexible recirculation ratio adjustment.

• Compact Design with High Flow Capacity – Optimized for low-head and large-flow recirculation, ensuring efficient mixing and stable hydraulic performance.
• Excellent Nitrogen Removal Performance – Suitable for nitrate return, denitrification, and biological nitrogen removal processes.
• Premium Stainless Steel Structure – SS304 impeller and motor housing with SS420 shaft provide outstanding corrosion resistance and long service life.
• Reliable Underwater Operation – IP68 protection, double mechanical seal, and nitrile rubber sealing system ensure continuous and maintenance-free operation.
• Flexible Installation & Control – Available with guide rail or wall mounting, adjustable blades, and VFD speed regulation for different wastewater treatment conditions.

To select the appropriate submersible nitrate recirculation pump, first determine the required internal recirculation flow rate. In denitrification systems, the recirculation rate is typically determined by the process design, the nitrogen load in the influent, the nitrate concentration, and the target total nitrogen removal rate.

Next, please confirm your actual head requirement. Nitrate recirculation pumps are typically used in low-head applications, but you should still verify the water level difference, piping losses, wall penetrations, channel layout, and installation depth.

VM-W series models can be installed on a rail or mounted on a wall. Please provide us with the tank depth, wall cutout location, lifting plan, and available maintenance space.

If your wastewater treatment plant requires flexible operation, we recommend selecting a denitrification recirculation pump controlled by a variable frequency drive (VFD). This allows operators to adjust the recirculation ratio during varying influent loads or seasonal process changes.