There is a growing need for more sustainable wastewater treatment technologies to provide non-conventional water sources. Constructed Wetland systems (CW) are viewed as a low-cost treatment technology with proven treatment efficiency. CWS can treat a variety of contaminants using low energy and natural systems by altering various design parameters. There are two configuration types of constructed wetlands: vertical (VF) and horizontal flow CW (HF). Both configurations have been widely adopted in both large and pilot scale studies with proven records of reasonable wastewater treatment efficiency. The current article reviews the recent development of CW technology and highlights the main achievements and successful applications for wastewater treatment at various locations. The review has indicated that a considerable removal efficiency is attained while using engineered CW systems with variable treatment rates for various pollutants. The treatment efficiency is a function of various parameters including wastewater type, scale dimensions, applied plant and the retention time. The review compared the treatment efficiency for both VF and HF and has revealed that various removal rates of BOD, COD, TSS, TN, TP and NH₄ was attained using both configurations. Yet, the removal efficiency in the case of VF was slightly higher compared with the HF with an average treatment level of 77% and 68% was achieved in both systems, respectively. The review revealed that the CW is an effective and sustainable technology for wastewater treatment with the initial influent level, microbial biofilm, detention time, plant species and configuration among the most dominating parameters that are directly controlling the removal rates.

The circular economy (CE) is a promising model in industrial waste management, offering viable long-term resource sustainability. The rising costs of the oil and gas industry make circularity a reliable approach for saving materials, money, and energy. In recent years, attention has risen to the need to apply CE within oil and gas produced water (PW) treatment. The most common treatment practice for PW is based on mechanical treatment, with optional disposal of treated water into deep wells. However, this procedure consumes a lot of energy, increases operational costs, and causes environmental risks. This research aims to propose sustainable treatment technology promoting circularity by introducing a novel nature-based solution to treat PW. The main research objective is to develop a circular model for PW treatment by investigating the treatment of PW using constructed wetlands (CWs) to sustainably reduce the amount of waste in oil and gas fields. Additionally, investigate the use of industrial wastes as filtration materials for CW systems. In this study, eight different laboratory-scale CWs models were designed and tested. The CWS operated in two different types of flow directions: vertical (VF) and horizontal flow (HF). The main filter media for the CW system included aggregates, activated carbons, plastic, and shredded tires. The study investigated the removal rates of Total suspended solids (TSS), Total dissolved solids (TDS), Oil and Grease (OG), and Total Petroleum Hydrocarbon (TPH) from the PW. Testing the CWs, it was found that the results of the PW treatment were promising, with the potential for more future shredded tires and plastic applications. All systems were effective at removing contaminants from produced water, with the highest recorded removal efficiencies of 94.8% TSS, 33.7% TDS, 90.2% OG, and 98.4% TPH. The research results were efficient and promoted the circular use of CW in PW treatment in addition to the possibility of reusing the treated effluent in agriculture and irrigation.

The United Nations Sustainable Development Goals’ (UN SDGs) action call promotes worldwide social, environmental, and economic prosperity. Each country developed a local plan to achieve the SDGs’ objectives and targets. The UN presents an annual global SDG progress report, based on an international indicator framework and regional available data. Wetland ecosystems contribute to the SDGs; however, more research is required to evaluate wetlands’ impact on sustainable development. This study investigates how implementing constructed wetlands (CW) at a local scale can contribute to achieving and promoting the SDGs with application in Kuwait. A preliminary design of a constructed wetlands wastewater treatment system is proposed alongside a local scoring framework based on regional information to assess the future projection of the SDGs in Kuwait. Overall, CW implementation plans contributed positively to improving the level of achievement of SDG 2: Zero Hunger, SDG 3: Good Health, SDG 6: Clean Water, SDG 7: Affordable and Clean Energy, and SDG 15: Life on Land. The analysis also highlights synergies that need to be considered for integrated environmental governance and enhanced policy coherence for Kuwait’s sustainable development management.