Application Of Constructed Wetlands With Modified Substrate In Produced Water Treatment

Produced water also known as oilfield brine is one of the largest waste by volume produced during oil and gas exploration activities. Its high volume, complex composition, environmental and health hazards makes it one of the most critical waste in the waste stream of the oil and gas industry. Most wastewater treatment methods employed in the treatment of PW are often energy-intensive, costly, and generate harmful by-products. With more stringent regulations on produced water handling and disposal, there is the need for the application of more efficient yet cost effective, less energy intensive and minimal by-products systems. One of such system is the constructed wetland that mimics nature. To this end, this study investigated the performance of a constructed wetland system with modified substrates for the treatment of produced water, focusing on the removal of heavy metals (Cd, Pb, and Zn) and oil and grease (O&G). A batch scale, three (3) constructed wetland experimental setup arranged in series was established. Gravel, coarse sand, loamy soil, and biochar were used as substrates. Phragmites australis, a common reed species was planted in each constructed wetland. Heavy metals were analyzed using Atomic Absorption Spectrophotometer while oil and grease was analyzed by gravimetric method. Results of the study demonstrated appreciable removal efficiencies for heavy metals (Pb: 82%, Cd: 75%, Zn: 74%) and O&G (86%) within a short hydraulic retention time of 45 minutes. This suggest that constructed wetland with a biochar layer can serve as an effective and eco-friendly treatment method for produced water.