Treatment of metronidazole pharmaceutical wastewater using pulsed switching peroxi-coagulation combined with electro-Fenton process
Yongjun Liao,
Yongbei Ye,
Xindi Chen,
Haoran Xin,
Shuyue Ma,
Songwei Lin,
Haiping Luo
Affiliations
Yongjun Liao
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Yongbei Ye
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Xindi Chen
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Haoran Xin
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Shuyue Ma
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Songwei Lin
Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
Haiping Luo
Corresponding author.; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510006, China
The aim of this study was to investigate the metronidazole (MNZ) degradation and real MNZ pharmaceutical wastewater treatment in the pulsed switching peroxi-coagulation (PSPC) process. Different pulsed switching frequencies and running times of H2O2 and Fe2+ productions were tested in the PSPC process. Results demonstrated that MNZ removal of 96.9 ± 1.2 % was realized in the PSPC process with a 200 mg/L MNZ and 0.1 M Na2SO4 solution within 80 min under a pulsed switching frequency of 6s: 1s and a current density of 20 mA/cm2 (H2O2) and 20 mA/cm2 (Fe2+). High MNZ removal could be attributed to efficient •OH production with the highest •OH concentration reached 321 ± 15 μM in the PSPC process. The hydroxyl and carboxyl groups of MNZ were sequentially oxidated by •OH and mineralized based on seven identified intermediates during the MNZ degradation. However, only 56.9 ± 6.7 % of COD was removed in the real MNZ wastewater treatment by the PSPC process within 90 min. A PSPC combined with electro-Fenton (EF) process was developed to enhance the COD removal in the MNZ wastewater. With MNZ wastewater as electrolytes, 3.3 ± 0.3 g/L of H2O2 was produced in a conventional EF reactor. The final COD removal reached 86–90 % using the mixture of effluent from the PSPC, the anode, and cathode chambers of the EF reactor, resulting in less than 80 mg/L COD in the effluent. Results from this study should provide a useful way to enhance real MNZ pharmaceutical wastewater treatment.
