Investigating the Optimal Conditions for Heavy Metal Removal from Oilfield Wastewater by Activated Carbons Using Response Surface Methodology

Abstract Oilfield wastewater, also known as produced water, presents an environmental concern due to its high concentration of heavy metals. Effective treatment strategies are necessary to address this issue. In the Niger Delta oilfields and refineries, produced water is a waste stream containing hydrocarbons, heavy metals, and other pollutants. This research focuses on utilizing Response Surface Methodology (RSM) to optimise metals’ adsorption process using activated carbon. Activated carbon is well known for its ability to adsorb various substances. It is being explored for its potential to reduce heavy metal pollutants from the wastewater of the Field X oilfield. To enhance the adsorption capacity, coconut husk-based activated carbon is modified with oxide, an emerging material derived from graphite using the "wet impregnation technique." A systematic experimental design is employed to analyze how various factors influence adsorption. The data obtained is then subjected to response surface methodology (RSM) using Design Expert software for analysis. This study considers factors such as adsorbent dosage, contact time and temperature. The significance and impact of these operating factors on the removal percentage (%) of pollutants will be tested using ANOVA (analysis of variance) with a correlation coefficient (R2) while maintaining a significance level of p < 0.05. The adsorption efficiency was determined by measuring final concentration, with a 93.59%, 99.01% and 96.38% reduction observed for Nickel, Cadmium and Lead respectively. The concentration values decreased from 0.6121 to 0.039 for Nickel, 0.9067 to 0.009 for Cadmium and 2.9044 to 0.104 for Lead. The findings from this study provide efficient approaches to tackle the environmental issues linked to heavy metal pollution in oilfield wastewater from field X. This will contribute towards promoting practices in the Nigerian oil and gas industry.