Pilot scale superficial flow constructed wetlands for sulfide and phenol removals from oil field produced water

• Ninoska Paz Universidad del Zulia-Venezuela
• Edith Blanco Universidad del Zulia-Venezuela
• Edixon Gutiérrez Universidad del Zulia-Venezuela
• Marisel Núñez Universidad Nacional Experimental Rafael María Baralt (UNERMB)-Venezuela
• Yaxcelys Caldera Universidad del Zulia-Venezuela

Palabras clave: surface flow constructed wetland, oil field produced water, emergent aquatics plants, sulfide and phenol removal

Resumen

During the oil extraction, a high amount of water is generated which disposal is of concern because they can become a pollutant agent causing a negative impact on the environment. In this study, the efficiency of free surface flow constructed wetlands (FSFCW) at pilot-scale for the removal of sulfides and phenols from oil field produced water (OPW) was evaluated. The experimental design consisted of two FSFCW (FSFCW I y FSFCW II) with gravel and soil (as media) and emergent aquatic plants. Cyperus luzulae and Cyperus ligularia were planted in FSFCW I while Cyperus feraz L, Paspalum sp. and Typha dominguensis were planted in FSFCW II. A control (C) without plants was also evaluated. The wetlands were fed with OPW from a continuous flow tank, the hydraulic retention time (HRT) was 7 days, and the effluent samples were collected weekly during 80 days. Removals of 69% for sulfides and 71% for phenols were observed in the control system. Lower removal percentages were achieved in planted systems (FSFCW I: 62% for sulfides and 64% for phenols; FSFCW II: 66% for sulfides and 61% for phenols). The aquatic plants did not play a fundamental role in the removal sulfur and phenols from oil field produced water.