The degree of treatment ...

The degree of treatment required depends on the discharge  standards you are required to comply with, as well as on the characteristics of the wastewater one is treating. The flowsheet you describe, if properly sized and operated, should be effective in removing total suspended solids as well as associated organic matter (BOD/COD). Not knowing the composition of the influent, it is difficult to know if what you are proposing is optimal or not. If removal of suspended solids is all that is required, your system will probably do the trick. However, if there is significant dissolved BOD or COD that has to be removed, you should be looking at biological treatment. Given the nutrients present in cashews, wastewater will probably be highly biodegradable.  Test the effluent for total and dissolved COD, compare with the requirements you need to attain and you will see if additional treatment is needed.