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

Abstract

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.