There is too much Iron and ...

There is too much Iron and Manganese, which have to be removed firstly with pretreatment (you can ask for that treatment). 

Second stage pretreatment need for pH adjustmen, aand third stage for clarification (suspended solids removal).

The RO unit has to be calculated using seawater membranes at high pressure operation. Depending on the use of the produced water it will maybe need a second stage RO unit pass.