Anaerobic sludge mixture

[nilaypathak]

We have 8 diameter tank to hold primary sludge. We are looking for sludge mixture to produce volatile fatty acid (VFAs) under anaerobic condition. Any suggestion on vertical mounted Vs submerged mixture. We had submerged mixture but it accumulate the sludge on the walls and not producing good mix.
Thank for you time and input.
Regards,

 

[bimr]

Is that 8 meter diameter? How tall is the tank?

A top mounted mixer will generally provide better results.

 

[MartinLe]

How thick or thin is your sludge? Total solids? What are the solids, what is the sludge from? Do you have a problem with heavy or light fraction?
What does "accumulate sludge on the walls" mean?

The general wisdom is that for good, efficient mixing you want a large mixer. For 8m dfiameter a top mounted mixer seems to be the way to go.