Produced water (PW) is seen as one of the largest waste streams emanating from the oil and gas industry. Often, PW is highly saline and exhibits high oil contents. Therefore, it cannot be discharged into the environment directly. Rather, very often, PW is treated rudimentarily and subsequently injected into disposal wells in the sub-surface. An initial water–oil separation is achieved with a three-way separator, frequently followed by gravity-based separations, such as with hydrocyclones. Further treatment, which adds to the cost of the operation, depends on the potential utilization of PW as a fresh-water substitute for drilling and workover operations, or enhanced oil recovery methods within the oil and gas industry itself, as a source for recoverable commercial salts such as calcium carbonate and sodium chloride, or as a source of water for cooling or for irrigation, the latter especially in regions that are water-scarce, where the utilization of treated PW as an alternate water source can contribute significantly to the water production of a country.

In the current paper, the treatment of PW from a South Kuwaiti oilfield is examined to explore whether the generated PW can, upon such treatment, be disposed of in an environmentally safe way, and whether the generated PW can deliver commercial products such as salts and usable water of adequate purity to make the treatment economically sustainable. Different treatment methods, such as ceramic membrane filtration and sorption filtration on biomass, both for the separation of residual oil from water, the precipitation of calcium as calcium carbonate, and solar evaporation/distillation for the recovery of salts and purified water, have been examined experimentally, where products of adequate purity could be obtained to make them commercially viable.

Finally, different combinations of treatment methods for the purification of PW have been assessed for their economic feasibility in the state of Kuwait.