It depends on the type of wastewater. In the raw sewage water, you can assume the VSS around (30 - 40%) of total SS. However, the water treated after primary classifier has 65 - 80% VSS. Finally, the fraction of VSS in total SS depends on the type of wastewater.

Hope this answer helps you.

Vss=0.8×SS

VSS or MLVSS is 80 percent of TSS for aeration tank.

According my opinion it is not possible to tell that VSS is 80 % of TSS. You can see opinion at https://www.watertechonline.com/the-measurement-of-suspended-solids/ that it is 75 %. The reason is that percentage of VSS depends upon technological parameters of wastewater treatment like sludge age (longer age lower VSS percentage bacause of mineralization of sludge). It means that at first the treatment technology must be defined to assess percentage of VSS.

Best regards

Vit

there is no shortcut for this. it purely depends on the waste type. if you take sewage then it may be as high as 90% whereas if you solely consider street sweeping i.e. a fraction of storm water, it may be as low as 40-50% (since it mostly includes inert).

I agree with Singh answer above " It depends on the type of wastewater. In the raw sewage water, you can assume the VSS around (30 - 40%) of total SS. However, the water treated after primary classifier has 65 - 80% VSS. Finally, the fraction of VSS in total SS depends on the type of wastewater"

VSS more thane SS is possible?

VSS is basically active bacteria (C5H7N02, MW=113). In my opinion, VSS is a subset of TSS.