Distillation of oil field produced water for reuse on irrigation water: evaluation of pollutants removal and ecotoxicity

Desalination is one of the earliest forms of saline water treatment and it is still used throughout the world. In this work, a single-effect mechanical vapor compression (MVC) process was investigated to produce water for irrigation of non-edible cultures from oil-field produced water. Distillation was able to produce a condensate presenting very low amounts of 84 analyzed pollutants. Ecotoxicological assays with Pseudokirchneriella subcapitata algae, Danio rerio fish, lettuce ( Lactuca sativa ) and earthworm ( Eisenia fetida ) were performed in condensate. The condensate was non-toxic for all tested organisms, except for P. subcapitata algae that showed some level of chronic toxicity caused by ammonium nitrogen. This toxic effect was confirmed by conducting a series of ecotoxicological assays with condensate samples after ammonia removal (stripping). The condensate presented quality acceptable for irrigation of non-edible crops.