Treatment of produced water from Niger Delta Oilfields using chemically modified sponge gourd (Luffa cylindrica)

Produced water (PW) from oil and gas reservoirs usually contains heavy metals and other contaminants that are generally harmful to the environment and ecosystem. Previous studies have shown that some local bio-adsorbents can effectively reduce the concentration of heavy metals. However, these bio-adsorbents easily degrade and have short lifespans, hence the need for modification. In this study, sponge gourd (Luffa cylindrica) was modified with sodium hydroxide (NaOH(aq)) at two different concentrations (3% and 5%). Samples of produced water randomly obtained from two different oil fields in the Niger Delta were treated with modified and unmodified adsorbent (L. cylindrica) and analyzed for heavy metals using an Atomic Absorption Spectrophotometer (AAS). The concentrations of Mn, Cr, Zn, Cu, Pb, Fe, Ni, and Cd in PW were reduced by 88.2, 79.6, 60, 67, 63, 68, 95, and 56% after treatment with modified L. cylindrica (3% NaOH), compared with 98, 100, 97, 79, 88, 87, and 100%, respectively, after treatment with modified L. cylindrica (5% NaOH) for 4 h. A forced degradation test carried out under microbial conditions to determine the degradability of the unmodified and modified L. cylindrica showed that the unmodified L. cylindrica sample had weight losses of 23 and 48% after 14 and 28 days, while the modified L. cylindrica experienced weight losses of 5 and 17% after 14 and 28 days, respectively. It can be concluded that improved treatment of produced water from Niger Delta oil fields can be achieved using modified L. cylindrica. Modified L. cylindrica is slower to degrade than unmodified L. cylindrica. Key words: Produced water, heavy metals, sodium hydroxide, sponge gourd.