Manganese recovery and ammonia nitrogen removal from simulation wastewater by pulse electrolysis

• PC electrolysis was developed to recover manganese and remove ammonia nitrogen.
• Manganese could be reduced from 160 mg L−1 to 0.2 mg L−1 for 2.5 h.
• Ammonia nitrogen could be removed from 80 mg L−1 to 0.1 mg L−1 for 2.5 h.
• Manganese was mainly recovered in the form of manganese dioxide.

Ammonia nitrogen- and manganese-contaminated water poses a considerable threat on the safety of water resources. In this work, pulse current (PC) electrolysis, a novel process, was developed to recover manganese and remove ammonia nitrogen from simulation wastewater simultaneously. Accordingly, the parameters of pulse electrolysis, and technological conditions, including temperature, initial pH, and concentration of addition NaCl, were investigated. The results showed that the concentration of manganese in simulation wastewater could be reduced from 160 mg L−1 to 0.2 mg L−1, meanwhile, ammonia nitrogen could be removed from 80 mg L−1 to 0.1 mg L−1 for 2.5 h PC electrolysis at 30 mA cm−2, 1000 Hz, and duty cycle 50% where settled with Ti/SnO2IrO2RuO2 electrodes, when the initial pH was 10.0 and NaCl addition was 0.008 mol L−1 at room temperature. Moreover, XRD and SEM analysis showed that manganese dioxide was deposited on the anode, and manganese in simulation wastewater was mainly recovered in the form of manganese dioxide.

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