ABSTRACT
Recalcitrant wastes including azo dyes, nitroaromatic compounds, halogenated compounds, heterocyclic compounds and other derivatives are of special concern owing to their recalcitrance and persistence in the environment. Bioelectrochemical systems (BESs), the innovative and efficient wastewater treatment technology, are regarded as a new sustainable and effective strategy for treatment of these wastes. This article reviews the state-of-the-art degradation and mineralization of recalcitrant compounds in BESs. Different kinds of recalcitrant wastes, such as azo dyes, nitroaromatic compounds, halogenated compounds and heterocyclic compounds are taken into account in detail in this review. Some recalcitrant compounds were able to be removed through either oxidation or co-metabolism in the anaerobic anode chamber of the BES. Meanwhile, other recalcitrant compounds with oxidizing groups were more easily removed through cathodic reduction in the BES cathode as they could serve as terminal electron acceptors under highly reducing conditions. The enhanced mechanisms for degradation and mineralization of recalcitrant compounds in the BES system were further discussed. At the same time, the scientific and technical challenges that are yet to be faced in the future were also summarized. It is expected that the review would attract more attention to this promising technology for recalcitrant compounds degradation that significantly contributes to its further development and application.
