Your BOD figure of 10 ppm for ...

Your BOD figure of 10 ppm for 3 day test is high as is ammonia of 2 mg/l and indicates sewage pollution . I assume the figure of 2000 mg/l TSS is an error as that is super huge. The rest looks like gulf seawater. A DMF solution before UF should ensure that and excellent feed to RO is maintained , However I would not use dual media , instead used mono media of a large grain biological active media (eg filtralite 2.5 mm to 4 mm) on which some biomass would grow over time and consume most of the readily biodegradable organics and ammonia. Let the UF do the job of fine particulate solids removal. Be very careful of the selection of UF , the key issue is often long term membrane integrity . Don't use any Ferric or polymer. A DMF and PSF solution correctly sized will also work provided that any dosing of chlorine is not allowed onto the DMF. But this will need lots of Coagulant and acid . If the TSS is really very high (> 50 mg/l) then a filter media solution is incorrect . You will need a gravity settlement step to drop out much of the solids probably with some coagulant use.