Does Ovivo provide motor starter or VFDs? Would VFD be needed/recommended?

If desired, VFDs can be used, but this is a customer preference. We have some jobs that include a VFD but the majority do not. An advantage of VFDs is that they provide a soft start and further customization that allows for additional energy savings optimizxation and remote monitoring (amp draw readings can be sent directly to the SCADA system, etc.).

Can a LM mixer be installed on existing digester covers?

Yes, the LM mixer can be installed on any cover that can withstand the additional loads of the mixer. Ovivo has over a hundred of installations, on either concrete covers, radial beam steel covers (either floating or fixed) and truss covers. If a cover is not available (i.e. anoxic basin), Ovivo can provide a bridge to support the proposed LM mixer system.

Is there any difference between the membranes Ovivo uses for MBRs vs those for membrane thickeners?

No, Ovivo uses the same membranes for liquid and solids treatment. The difference lies in how we apply the membranes. In a typical MBR application a flux rate of 15 gallons per square foot of membrane material per day is normal. As the solids in a membrane thickener are much higher than they are in an MBR we derate or lower the flux rate for thickeners to approximately 5 gallons per square foot of membrane material per day to prevent premature fouling.

Q.What is the difference between the sludge ring and the sludge drum? Is there an advantage?

A.: he sludge ring is, very simply, a static ring anchored to the floor with multiple orifices spaced along its perimeter. Higher concentration sludge enters an orifice only where the spiral blade passes an opening, while sludge is sucked into all the ring’s orifices continuously. This may cause sludge dilution. The Sludge Drum is a dynamic enclosure which rotates with the rake arms. Because it rotates with the arms, the spiral blades are continuously feeding fresh concentrated solids into the drum adjacent orifice.