Oilfield water treatment by electrocoagulation–reverse osmosis for agricultural use: effects on germination and early growth characteristics of sunflower

ABSTRACT

This study aims to evaluate the effects of oilfield water (OW), treated by a hybrid process of electrocoagulation and reverse osmosis (EC–RO), on seed germination and early growth characteristics of sunflower (Heliantus annus L.). In the EC step, tests were conducted with 28.6 A m⁻² current density and 4 min. reaction time. In the RO step, the system was operated with 1 L min⁻¹ constant flow and 2 MPa, 2.5 MPa and 3 MPa feed pressures. In all feed pressures, RO polymeric membranes achieved very high removals of chemical oxygen demand (up to 89%) and oils and greases (100%) from EC-treated effluent. In best feed pressure (2.5 MPa), turbidity, total dissolved salts, electrical conductivity, salinity, toxic ions and sodium adsorption ratio values attained internationally recognized standards for irrigation water. Using EC–RO (feed pressure:2.5 MPa) treated OW, germinated sunflower seeds percentage (86 ± 6%), speed of germination (30 ± 2) and biomass production (49 ± 5 mg) were statistically similar to control (distilled water) results. Vigor index average values obtained using OW treated by EC–RO (3871)were higher than that obtained by OW water treated by EC (3300). The results of this study indicate that EC–RO seems to be a promising alternative for treatment of OW aiming sunflower crops irrigation, since the use of this treated effluent did not affect adversely seed germination and seedling development, and improved seedling vigor. Furthermore, OW treatment by EC–RO reduces sodium levels into acceptable standards values avoiding soil degradation.

KEYWORDS:

• Electrocoagulation
• oilfield water
• reverse osmosis
• sunflower
• irrigation

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCiD

Paulo S. A. de Souza http://orcid.org/0000-0003-1845-9330

Alexandre A. Cerqueira http://orcid.org/0000-0002-9546-2587

Michelle M. Rigo http://orcid.org/0000-0002-8204-284X

Julieta L. de Paiva http://orcid.org/0000-0003-3264-783X

Rafael S. P. Couto http://orcid.org/0000-0001-8349-1383

Fábio Merçon http://orcid.org/0000-0001-6293-6574

Daniel V. Perez http://orcid.org/0000-0003-4336-2223

Monica R. C. Marques http://orcid.org/0000-0001-6906-8327

Additional information

Funding

This study was funded by Rio de Janeiro State Research Foundation-FAPERJ [grant number E-26/112.211/2012].