Removal of recalcitrant trivalent chromium complexes from industrial wastewater under strict discharge standards

Abstract Various industries produce large amounts of wastewater containing chromium complexes, such as tanning, electroplating, printing and dyeing. The complete removal of chromium complexes through traditional precipitation and coagulation processes is difficult, which is a great challenge in meeting strict chromium discharge standards. To date, a large number of literature reviews on chromium ions removal processes have been published, but none on the removal of chromium complexes. To tackle the challenge and provide reference for future research, this review summarized the difficulties of chromium complex removal and systematically explores the research status of chromium-complex-removal technologies. The researches on chromium complex removal are mainly focused on the precipitation, biotechnology, adsorption and redox process. These technologies are reviewed in detail in terms of their technological mechanisms, main advantages and shortcomings. In general, the researches available are still not sufficient to solve this problem to date. And finally, the future research directions of chromium complex removal have been proposed.