Optimization for simultaneous removal of NH3-N and COD from coking wastewater via a three-dimensional electrode system with coal-based electrode materials by RSM method

Ting Su,Xiangdong Xing,Wenwen Gao,Xinzhe Lan,Yonghui Song

doi:10.1515/gps-2021-0072

Abstract

Abstract The present work demonstrated preparation of coal-based electrode materials (CEM)-derived low-rank coal for simultaneous removal of ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) from coking wastewater by a three-dimensional electrode system (3DES). The influence of important parameters in 3DES such as processing time, applied voltage, electrode plate spacing, mass of commercially activated carbon (CAC), and initial pH were investigated. Based on the central composite design, the response surface method (RSM) was employed in order to optimize the variable parameters in removal process of pollutants. From the analysis of RSM, the optimum conditions for 3DES were 4.5 h of processing time, 5.5 V of applied voltage, 17 mm electrode plate spacing, 4.5 g CAC, and pH of 3 with higher simultaneous removal rate of COD (74.20%) and NH3-N (51.48%). Besides, the content of N element (4.9%) and N containing groups were traced by SEM-EDS and FTIR analysis in order to verify the removal effect. The experiment results showed the capability of CEM for electrode system removal of pollutants from coking wastewater and obtained considerable simultaneous removal rate of NH3-N and COD.

Highlights

Coke industry plays an important role in economic construction and social development in China, and it is one of the pillar industries to maintain the steady economic growth
Certain results in a large number of research and practice were obtained after the new scientific and effective studies in coking wastewater (CW) treatment technology; the disadvantages of current treatment still exists in two aspects: (i) the content of NH3-N and chemical oxygen demand (COD) in the wastewater is still high after advanced treatment and the biochemical properties are poor [9] and (ii) in-depth treatment processes generally have limitations in popularization and application such as high investment costs, high operating costs, harsh reaction conditions, and unstable operation
A quantitative amount of commercially activated carbon (CAC) was added to electrochemical system and stirred them in the whole process with a magnetic stirrer. 50.0 mL of diluted CW were consumed for batch experiments, and the removal rates of NH3-N and COD were measured at different conditions

Summary

Introduction

Coke industry plays an important role in economic construction and social development in China, and it is one of the pillar industries to maintain the steady economic growth. Certain results in a large number of research and practice were obtained after the new scientific and effective studies in CW treatment technology; the disadvantages of current treatment still exists in two aspects: (i) the content of NH3-N and COD in the wastewater is still high after advanced treatment and the biochemical properties are poor [9] and (ii) in-depth treatment processes generally have limitations in popularization and application such as high investment costs, high operating costs, harsh reaction conditions, and unstable operation These problems have attracted more attention to the field of CW treatment technology, which restricted the green and efficient development of coke industry, and more effective approaches for removing NH3-N and COD in CW need to be explored

Objectives

Methods

Findings

Conclusion