Application of circular economy in oil and gas produced water treatment

The circular economy is a promising model in industrial waste management offering viable long-term resources sustainability. The rising costs of the oil and gas industry make circularity a reliable approach for saving materials, monetary and energy resources in various activities management. A circular economy approach within oil field produced water PW treatment gained attention in recent years with few implementations of PW reuse for irrigation purposes. The most common treatment practice for PW is based on mechanical treatment with optional disposal of treated wa-ter into deep wells. However, this procedure consumes a lot of energy, and operational costs and causes environmental risks. This research aims to propose sustainable treatment technology pro-moting circularity by introducing a novel nature-based solution to treat the PW using industrial wastes as filter media for proposed constructed wetland CW systems. In this study, eight different laboratory-scale CWs models were designed and operated. Two different types of flow directions, vertical (VF) and horizontal flow (HF) to test the efficiency of treating PW using CWs. Four differ-ent materials were used as the main filter media for the CW systems. Selected materials included aggregates, activated carbons, shredded tires, plastic, and shredded tires. The study investigated the removal rate of Total suspended solids TSS, Total dissolved solids TDS, Oil and Grease OG, and Total Petroleum Hydrocarbon TPH from the PW. Testing the CW systems in three different operating scenarios, it was found that the four filter materials proved excellent PW treatment with the potential of plastic and shredded tires applications. All systems were effective at removing contaminants from produced water with the highest recorded removal efficiency of 94.8% TSS, 33.7% TDS, 90.2% OG, and 98.4% TPH. The results of these tests were promising and promoted the circularity of waste materials as filters for treating wastewater in addition to the possibility of reusing the treated PW for agriculture and irrigation.