Activated sludge treatment for promoting the reuse of a synthetic produced water in irrigation

Large volumes of produced water are generated as a byproduct in activities of oil and gas exploitation, which can be reused in agriculture after a treatment process. Activated sludge treatment has been successfully used to remove oil from wastewater, but systematic studies on the toxicity of this effluent using this treatment are scarce in the literature. In this study, it was investigated the performance of an activated sludge system in the treatment of a synthetic produced water under different initial conditions in terms of salinity and oil and grease concentration. Furthermore, it was evaluated this effluent phytotoxicity in the germination, and seedling and plant growths of sunflower and corn seeds using untreated and treated synthetic produced water. Results revealed the activated sludge effectiveness in oil and grease and salinity removal from produced water, viz. high removal efficiency of 99.01 +/- 0.28 and 91.07 +/- 0.39%., respectively. Untreated produced water showed considerable toxic effects on the germination (74.67 +/- 2.31% and 82.67 +/- 2.31 for sunflower and corn seeds, respectively) and growth stages of sunflower and corn seed plants. The germination percentage was approximately 100% for both types of seed. The seedling and plant growth of the two seeds irrigated with treated produced water had similar performance when used tap water. These results highlighted the potential reuse as an unconventional water resource for plant irrigation of the synthetic produced water treated by an activated sludge process, which technology has showed high removal performance of salinity and oil.

Automated summary

This study investigated the performance of an activated sludge system in treating synthetic produced water under different initial conditions, showing high removal efficiency of oil and grease and salinity. The effluent toxicity on seed germination and plant growth was evaluated, highlighting the potential reuse of treated produced water for plant irrigation.