Ovivo® Mem-TAD™ Process

Ovivo® Mem-TAD™ (Membrane Thickened Aerobic Digestion) process brings aerobic digestion and flat sheet membrane performance together into one integrated system. The system consists of two or more aerobic digesters operating in conjunction with an anoxic basin and membrane thickener (MBT). One aerobic digester forms a recycle loop with the MBT and the anoxic basin that causes digested sludge to be continuously thickened while undergoing nitrification and denitrification.
  • Class B Biosolids
  • Expands the capacity of existing tanks
  • Minimizes the footprint of new construction
  • Minimizes nutrients being returned to the upstream liquid treatment process
  • Low operating costs

SD20150910-01BAre you running out of space in your existing aerobic digesters? Do you want to expand your capacity without building any new tanks? Do you have limited footprint for new construction? If you answered yes to any of these questions then look no further than the Ovivo Mem-TAD system. The Ovivo Mem-TAD system utilizes flat sheet membranes to remove water from the sludge in the aerobic digesters increasing the solids concentration up to 4.5%. This expanded capacity allows facilities to meet Class B criteria in a compact footprint. An added benefit of the membranes is that they do not allow any particulate phosphorus to pass through the membranes thus lowering the nutrients being returned to the front of the plant.

  • Customized designs guaranteed to meet Class B biosolids criteria
  • Eliminate the need for polymer or coagulant to thicken sluge
  • Ease of installatioin means lower total cost of ownership
  • Continuous thickening independent of wasting schedule
  • Ease of operation allows operators to focus on liquid treatment process

The Ovivo Mem-TAD system provides unparalleled value by offering one of the lowest total cost of ownership available in the market today. This is achieved due to the unique nature of the flat sheet membranes used in the Mem-TAD system. The flat sheet membranes allow the sludge in the digesters to be concentrated up to 4.5% solids without using any polymer or coagulant. This has the two-fold benefit of shrinking digester volumes and lowering chemical costs.

Another factor lowering the total cost of ownership is the ease with which the membranes are installed in existing tanks, making expanded capacity very affordable. Finally, the membranes operate around the clock, allowing solids wasting to occur independent of operational staff being present. Thus operation resources are better able to focus on the liquid treatment process.

The Mem-TAD process consists of a membrane thickener (MBT) tank, and two aerobic digesters. All blowers, permeate pumps, pumps, and instrumentation are included in the process package to ensure one source of responsibility.

Waste activated sludge is wasted directly from the liquid treatment process into a fine screen and emptied into Digester One. The screened flow is transferred at a rate of at least 4Q into the MBT tank via a pump. Sludge is thickened to 3.0% solids by the MBT by pulling clean water through the membrane leaving solids behind. Because of the quality of filtration by the membrane, the permeate from the thickener may be combined with the treated effluent flow that is to be sent to disinfection instead of recycling back to the headworks of the treatment facility. The thickened sludge from the membrane thickener is transferred over a weir into Digester One, the first stage, in-loop digester. In this digester the sludge is actively mixed and digested with the aid of Ovivo’s single drop air diffusers. A portion of the partially digested flow from the in-loop cycle is transferred to Digester Two for second stage digestion via weir overflow or telescoping valve.

During digestion, the in-loop zones (the membrane thickener and Digester One) provide nitrification and volatile solids reduction while the isolation loop provides time for denitrification, pH stabilization and improved pathogen destruction.

Don’t membranes require a lot of extra equipment?

No not really. Besides the membranes themselves you need a fine screen, air scour blower, permeate pump and control system. When all is said and done it’s similar to the equipment needed for any other mechanical thickening system.

How long has this technology been around?

Ovivo has been using membranes in aerobic digestion for over a decade. In that time we’ve installed membrane digestion systems at more than 30 wastewater treatment plants, including the largest membrane digestion system in the world at Cayce, SC.

How long will the membranes last?

We expect the membranes to last for at least 10 years, though lifetime warrantees are available.

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