How to reduce scaling on MBBR media for dairy wastewater?

The Challenge

Wastewater from dairy operations is typically high in strength, quite variable, and challenging to treat. The wastewater stream at this particular facility had elevated concentrations of calcium and phosphorus. 

This characteristic created a significant amount of scaling on the biofilm carriers of the client’s existing MBBR (Moving Bed Biofilm Reactor). The MBBR was designed to be a pretreatment step prior to an activated sludge process; however, the excessive scaling caused a significant amount of the media to sink to the bottom reactor. This prevented the system from reducing total soluble COD and caused the downstream treatment processes to become overloaded during peak flow rates. The client needed to find a cost-efficient solution to accommodate the increasing flow rates of its high-strength waste stream.


The Solution

Veolia was able to retrofit the client’s existing MBBR with the newly designed Z-MBBR media by AnoxKaldnesTM.

The Z-MBBR’s innovative design creates multiple benefits over traditional MBBR media types. It allows the media to self-clean and maintain a consistent biofilm thickness. While moving in the reactor, the carriers scour each other to remove excess growth and limit scaling. The elevated grid pattern of the Z-MBBR media allows the biofilm to grow within a protected area and maintain a uniform thickness on the carrier.


The Results

Performance of the retrofitted MBBR with the Z-MBBR media has exceeded expectations. The media has limited scaling and the system is removing an average of 42% of soluble COD. 

The enhanced MBBR pre-treatment step has improved the operation of the entire wastewater system. The largest benefit to the client is that it significantly reduces the load on downstream processes to maximize the treatment performance and to provide additional treatment capacity.

Key Figures


  • Flow: 800,000 gpd
  • BOD: 23,352 lb/d 
  • COD: 34,340 lb/d
  • TSS: 6,667 lb/d
  • NH3-N: 100 lb/d
  • Temperature: 25°C - 40°C
  • pH Range: 6.0 - 9.0