Cross-flow ultrafiltration of hydrocarbon emulsions

The conventionally treated oil refinery wastewaters contain about 20 mg/l total hydrocarbons and 30 mg/l suspended solids sloughed from a biological reactor. The new European standards will require less than 5 mg/l total hydrocarbons and less than 10 mg/l suspended solids. Such standards could be met by an ultrafiltration treatment. The M9 Carbosep membrane was selected after it proved to be a total barrier for the hydrocarbons of a synthetic emulsion while ensuring the higher flux. The importance of the temperature is emphasized as it determines the droplet size distribution. The major limiting processes conditioning the fouling are evidenced and explained by the mean droplet size and the size distribution. The fouling is then quantified and linked to the operational parameters. A relationship for the limiting flux is fitted to the experimental data.