Process Optimization of Electrochemical Treatment of COD and Total Nitrogen Containing Wastewater

Jiachao Yao, Yu Mei, Junhui Jiang, Guanghua Xia and Jun Chen
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Jiachao Yao: College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China
Yu Mei: College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China
Junhui Jiang: The Engineering Technology Center of Pollution Control in Taizhou, Taizhou 318000, China
Guanghua Xia: College of Life Science, Taizhou University, Taizhou 318000, China
Jun Chen: College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015, China

IJERPH, 2022, vol. 19, issue 2, 1-12

Abstract: In this work, an electrochemical method for chemical oxygen demand (COD) and total nitrogen (TN, including ammonia, nitrate, and nitrite) removal from wastewater using a divided electrolysis cell was developed, and its process optimization was investigated. This process could effectively relieve the common issue of NO 3 − /NO 2 − over-reduction or NH 4 + over-oxidation by combining cathodic NO 3 − /NO 2 − reduction with anodic COD/NH 4 + oxidation. The activity and selectivity performances toward pollutant removal of the electrode materials were investigated by electrochemical measurements and constant potential electrolysis, suggesting that Ti electrode exhibited the best NO 3 − /NO 2 − reduction and N 2 production efficiencies. In-situ Fourier transform infrared spectroscopy was used to study the in-situ electrochemical information of pollutants conversion on electrode surfaces and propose their reaction pathways. The effects of main operating parameters (i.e., initial pH value, Cl − concentration, and current density) on the removal efficiencies of COD and TN were studied. Under optimal conditions, COD and TN removal efficiencies from simulated wastewater reached 92.7% and 82.0%, respectively. Additionally, reaction kinetics were investigated to describe the COD and TN removal. Results indicated that COD removal followed pseudo-first-order model; meanwhile, TN removal followed zero-order kinetics with a presence of NH 4 + and then followed pseudo-first-order kinetics when NH 4 + was completely removed. For actual pharmaceutical wastewater treatment, 79.1% COD and 87.0% TN were removed after 120 min electrolysis; and no NH 4 + or NO 2 − was detected.

Keywords: electrochemical oxidation; electrochemical reduction; COD; total nitrogen; wastewater treatment (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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