Abstract
The Kingdom of Saudi Arabia (KSA) is a hot, arid, and water-scarce country in the driest region of the world. With daily water usage of 263 l per capita, the Kingdom has an absolute water shortage threshold of 89.5 cubic meters per capita per year. Aquifers, the country's main natural water source, have been severely depleted. Desalination provides 60% of the country's water, with the remainder coming from non-renewable groundwater (less than 40%) and reclaimed wastewater and surface water supplies. Increased wastewater treatment capacity has also given KSA a new way to address its water crisis. KSA aspires to become the largest market in the Gulf Cooperation Council for treated wastewater and water reuse, a viable alternative to desalinated water in non-potable uses. Constructed wetlands (CWs), a natural wastewater treatment approach, can be a sustainable and successful co-generation solution for wastewater treatment. Contaminated water is converted into usable water using CWs. The goal of this work is to fill a huge research gap in the treatment industry by conducting a study on the performance of CWs in hot, arid, and dry climates, as well as bringing CW technology for wastewater treatment systems within Saudi Arabia. It covered vegetated plant activities, microorganism-mediated biological processes, biomass usage, CH4 extraction, opportunity, sustainability, and circular economy approaches. It reviewed the limited publications on CW in the Kingdom of Saudi Arabia (KSA) to summarize the current situation and investigate the technology's potential, and direct future studies in KSA, if any.