OVIVO® MS Diffuser

Ovivo® MS Diffuser offers excellent mixing and aeration by establishing a clear roll pattern within basins. The equipment is especially suited for digesters and sludge holding tanks which typically see a range of materials and may handle thicker solids concentrations. These diffusers are recognized as being non-clog diffusers. The air metering orifices are located above water level, accessible at all times, and do not require any cleaning. This is a guarantee no other diffuser can offer.
  • Mixes and aerates high solids
  • Simple, robust design
  • Long product life (sometimes over 20 years)


  • Concentrating solids leads to smaller tank footprints
  • Little to no maintenance required
  • Low total cost of ownership

Ovivo's Diffuser

The original MS® diffuser was conceived in 1968 by Mansel W. Smith, who was for many years the Superintendent of Sewage Treatment of the City of Austin, Texas and Robert H. Pyle, one of the founders of ENVIROQUIP, INC. During their years of testing all types of air diffusers for coarse and medium bubble aeration of activated sludge, they worked to develop a truly non-clogging diffuser. They found that the only way to eliminate clogging completely was to locate the metering orificing above the liquid level under aeration, and to use the principle of hydraulic shear to generate small air bubbles, rather than submerged orifices or pores. The only remaining problem would be the possibility of stringy materials fouling the discharge nozzle. The top of the air injector drop pipe is furnished with a plugged tee fitting so that in the event of fouling by stringy materials, a brush can be inserted at the top and run through the drop pipe and diffuser. However, this is seldom, if ever, required. 

It was discovered, through application, that the original MS diffuser is essentially self cleaning due to the flushing action that takes place when the water column in the drop pipe is expelled by the initiation of airflow to the diffuser head. Individual air mains can be purged in this way by closing the air valve to the header and opening the air bleed valve supplied for each header. This allows the process liquor to rise in the drop pipes. Closing the air bleed valve and rapidly opening the air supply valve results in a violent flushing jet that effectively purges the MS diffusers located on the end of the drop pipes. This is a very different situation from other air diffusers where backflow through the diffuser can cause severe fouling, and submerged check valves are needed to prevent this condition. Submerged check valves have been demonstrated to eventually fail, causing uneven distribution of air to the process. 

Typical Assembly

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