Circular Reuse of Onshore Oil and Gas Produced Water for Bioenergy Crop: Phytoextraction Using Nopalea cochenillifera for Recovery of Degraded Semi-Arid Lands in Brazil

Facing water scarcity and environmental contamination, a sustainable approach combining bioeconomy and circular economy principles has emerged: the use of onshore oil and gas produced water (PW) to irrigate Nopalea cochenillifera. This study evaluated the ability of Nopalea cochenillifera to phytoextract contaminants, focusing on translocation and bioaccumulation factors for the recovery of degraded soils. The experiment was conducted in a randomized block design with five treatments (T1: 100% supply water; T2: 75% supply water + 25% PW; T3: 50% supply water + 50% PW; T4: 25% supply water + 75% treated PW; T5: 100% PW) and five replicates in 20 L pots. After 240 days, plant and soil samples were analyzed for micronutrients (Cu2+, Mn2+, Fe2+, Zn2+ and Na+) and heavy metals (Cr, Ni, Cd and Pb). The highest median TF was observed for Mn in treatment T3 (10.55), while the highest median BF occurred for Cu in treatment T2 (10.852). Nopalea cochenillifera effectively translocated Mn, Zn, Ni, Cd, and Pb from roots to shoots and bioaccumulated all analyzed nutrients, particularly Cu, Mn, Fe, and Zn. PW irrigation altered elemental transport and intensified metals accumulation. Thus, Nopalea cochenillifera demonstrates strong phytoextraction potential for environmental remediation in semi-arid regions.