Fishead
Low energy swirl concentrators are commonly used to treat storm water with sizes ranging from .5 cfs to 10 cfs in off the shelf units and up to 120 cfs in off the shelf designs. There are several manufacturers of such devices many of whom may be able to help out in the design of a larger unit or setting up several units in parallel.
These units typically remove particles in the 250 micron down to 75 micron depending upon the type, model and size with up to 80% efficiency. At the flow you are looking at a maintenance system would need to be built into the unit cause all that sediment has to go someplace.
As storm water treatment devices, the removal of 1 to 2 tons per peak cfs per year is typical. but remember your application is continuous not intermittent like storm water treatment devices.
The above listed website, is not entirely accurate on the power requirements, there are head losses in any such device as well as losses in process water to flush the sediment away
Hydrae