Dear John, I recommend to ...

Dear John, I recommend to check the analysis of the raw water, because the dolubility of SiO2 at ambient temperature is about 150 mg/L and 600 mg/L may be reached only through oversaturation and solids suspended.

The elimination of SiO2 for high concentration is actually a hard task and the convenient technology should be chosen also considering the plant capacity/size. How much is the water flow to be processed ?

Probably evaporation is a good technology to be considered and a Multi effects evaporator can solve your problem. Please note that the non dissociated in ions silica flows through RO membranes thus making the RO separation rather ineffective. Moreover the use of ion exchanging (anionic) resins is not recommended because of the difficult regeneration of the resins saturated by SIO2

In any case DAF is to be installed before the SiO2 removal section. However 2000 ppm oil is much for a DAF and I suggest to install a CPI as primary treatment, and then a DAF as secondary treatment. The total oil can be thus reduced to less than 10 ppm, which is sufficient for the proper next evaporation process (not for resins nor for RO membranes)