A COMPARATIVE STUDY BETWEEN WATER HYACINTH (Eichhornia crassipes) AND WATER LETTUCE (Pistias stratiotes ) IN THE REMEDIATION OF PRODUCED WATER Edaigbini Philip Izuangbe 1 ; Samuel Ogbeide ; Dr.O.A.Olafuyi 2 ; Faculty of Engineering, University of Benin, P.M.B. 1126, Benin City, Nigeria ABSTRACT The study presents the characteristics of produced water obtained from a detention pit in the Niger Delta region of Nigeria. Phytoremediation, an emerging remediation technology for contaminated soils, groundwater, and wastewater that is both low-tech, low-cost, and environmental friendly have been employed in this study. Two aquatic macrophytes: water hyacinth (Eichhornia crassipes) and water lettus (Pistias stratiostes) have been used to remediate this produced water harmless in the environment. The two aquatic macrophytes were comparatively studied to determine their effectiveness in remediation without the use of fertilizers to sustain their growth. Also, physico- chemical parameters were compared with the Department of Petroleum Resources (DPR), stipulated discharge limits. Parameters such as pH, EC, salinity, TDS, TSS, DO, BOD, COD, turbidity, sulphate, phosphate, ammonia, oil and grease, Cu, Pb, Cr, Zn, Fe, and total coliform of the produced water have been studied using standard protocol of APHA and ASTM. The physico- chemical analysis revealed that most of the parameters were above the permissible limits and that water hyacinth made a better clean up than water lettuce. One-way ANOVA analysis of variance was used to test for significant difference. Recommendations were also made for better cleanup goals and plants survivals. Key Words: produced water, phytoremidiation, aquatic macrophytes, water lettuce, water hyacinth, contaminants. INTRODUCTION Water production during oil and gas extraction operations constitutes the industry’s most important waste streams on the basis of volume (Reynolds Rodney R., 2003). Produced water is any water that is present is a reservoir with hydrocarbon resource and is produced to the surface with crude oil or natural gas. In Nigeria, an estimated volume of about one billion barrels of water are disposed annually from oil and gas production operations. In offshore Niger Delta, produced water are normally pumped through slotted pipelines under the surface water, while for onshore operations, produced water are stored in detention pits before being discharge into the environment. The composition of this effluent contains a significant amount of contaminants which when present in high amount may constitute environmental pollution. In the Niger Delta, before effluents are