Because there is such a variety of filter options, it’s difficult to make a specific recommendation without understanding more about your situation. Filter designs can include pressure filters, open gravity cells, and self-backwashing filters. Media systems can include coal, sand, garnet, or combinations of these materials.
So it really depends on the issues that you’re facing with your effluent and what filter you believe will enhance your polishing process. From there, you can choose a manufacturer that creates the system which best benefits your current process.