Capacitive deionized hybrid systems for wastewater treatment and desalination: A review on synergistic effects, mechanisms and challenges

Abstract

• CDI hybrid systems are more promising than standalone CDI technology. • Current developments and challenges are extensively discussed. • MFC powered CDI systems are a suitable solution for sustainable water treatment. • Technical and economic barriers need to be overcome to make hybrid systems practical. The collective negative impact of both energy depletion and freshwater scarcity has inspired the researchers to develop effective water treatment approaches with lower energy consumption. Capacitive deionization (CDI), an emerging technology for water treatment and desalination is gaining global interest because of its ion selectivity, high water recovery and energy efficiency. Over the last two decades, CDI has gone through several modifications and advancements in terms of module configuration, electrode material and its applicability. For further enhancement in practicability and commercialization of CDI, researchers have shown a broad range of interest in CDI hybrid systems over the past few years. CDI modules have been integrated with photochemical, membrane separation, ion exchange, electrochemical oxidation and bioelectrochemical processes for desalination, wastewater treatment, energy recovery, resource recovery and performance enhancement. These integrated systems are more promising compared with standalone CDI technology. This comprehensive and state of the art review examine different CDI hybrid systems on the basis of working mechanism, module configuration, operating parameters and their effects on system performance. Moreover, synergetic effects, limitations and challenges of these hybrid systems towards their large scale implementation also have been addressed in this review paper.