Ahh... OK. I completely understand/agree with the Ultracept. There are other methods, but this is good to keep in the loop because the specific job it does, it does very well.
What I was originally thinking is that you were using the UF treatment and then RO in series, which could work very well for what you need. While the RO isn't appropriate for for the hydrocarbon emulsion, the UF excells at it and a UF system can be used to pre-process the water before the RO so that when the RO receives it you won't end up clogging up the RO membrane. But there are many solutions, that's for sure.
Another method you can us to scrub befofore either the UF or RO or both is by employing a Dissolved Air Flotation System (DAF). The DAF is the logical "in-between step" since it simply causes the emulsified oil bo rise to the top where it is skimmed off as a froth. When the water enters the system, it pumps it into a tank, which is then pressurized with air to the point of saturation in the water. The high pressure mixture is then sent up to the flotation tank, which is not presurrize, and when it gets there, the pressure is released as it fills the frothing tank, and the bubbles created attach to the solids and bring them up to the surface, where they are skimmed away. Actually, it's pretty ingenious, but quite simple. Here's an example of how one of these would be used.
Let me know your thoughts and we can continue to discuss. I'm realize there may be many factors determining what you can and can't do. So if anything I suggest isn't feasable for your use, just let me know and we can toss it out of the idea back.