Electrokinetic remediation with solar powered for electrolytic manganese residue and researching on migration of ammonia nitrogen and manganese

Abstract

With the development of manganese ore resources, a large number of electrolytic manganese residue (EMR) was produced, which causes serious environmental pollution (like water pollution, soil pollution, etc.). The control of water content and decomposition of compound salts are the key issues to harmless treatment of EMR. Among them, the control of ammonia nitrogen and manganese content and the decomposition of compound salts are the severe challenges facing the resource utilization of compound salt. Hence, from the perspective of environmental protection and energy-saving, this work adopted solar electrokinetic remediation methods to treat the EMR of an electrolytic manganese plant in Guangxi, then explores the changes of water content, pH value and NH4+-N and Mn2+ content in different regions of electrolytic cell. Besides, SEM, XRD and XRF were employed to analyze the basic physicochemical properties of the EMR before and after the remediation, from which it was found that under the action of an electric field, Mn2+ migrated directionally from the anode area to the cathode area and solidified into Mn(OH)2 and MnOOH. Meanwhile, NH4+-N migrated to the cathode, it formed (NH4)2SO4 on the surface of the EMR which can be easy to separate. After 72 h of solar electrokinetic remediation, the concentration of Mn2+ in the cathode area was decreased from 1725.5 mg L−1 to 84.3 mg L−1, and the NH4+-N content in the anode area declined from 907.9 mg L−1 to 196.4 mg L−1. In addition, (NH4)2(Mg, Mn, Fe)(SO4)2·6H2O and other compound salts can be decomposed into (NH4)2SO4 and (Mg, Mn, Fe)SO4, other single salts that can be cleaned easily under the action of the electric field.