Parameters optimization for eutrophic lake water treatment by a novel process of iron-carbon micro-electrolysis coupled with catalytic ozonation using response surface methodology

Shanqing Jiang,Pei Han,Liping Wang,Hankun Zhang,Qiuya Zhang,Yuanyuan Zhou,Yu Cao,Xia Xu,Yanan Zhang

doi:10.2166/ws.2021.074

Abstract

Abstract A novel process of iron-carbon micro-electrolysis (ICME) coupled with catalytic ozonation (CO) for treatment of eutrophic lake water was developed. A series of batch experiments with ICME alone and CO alone was designed to investigate the effects of process parameters, such as initial pH, dose of Fe-C, time of micro-electrolysis, ozone flux, dose of TiO2/activated carbon (TiO2/AC), and time of ozonation, on the removal rates of total nitrogen (TN), total phosphorus (TP), CODMn and Chl-a. The process parameters were optimized using response surface methodology. The results showed that initial pH, dose of Fe-C and ozone flux had significant effects on removal of TN, TP, CODMn and Chl-a. Within the range of selected operating conditions, the optimized values of initial pH, dose of Fe-C, time of micro-electrolysis, ozone flux, dose of TiO2/AC, and time of ozonation were 3.8, 13.7 g/L, 29.6 min, 3.19 L/min, 294.74 mg/L and 106.73 min, respectively. Furthermore, ICME alone had significant advantages in TP and CODMn removal and CO alone favored TN and Chl-a. Under the optimal process conditions, the final removal rates of TN, TP, CODMn, and Chl-a by the hybrid ICME-CO process reached 75.33%, 86.29%, 94.42% and 97.57%, respectively. The present research provides a new alternative technology with promise for treatment of eutrophic lake water.

Highlights

According to the latest survey, over 64% of the global lakes are eutrophic (Zhang et al )
The simulated eutrophic lake water was taken from Ruoyu Lake in Changzhou University, and ammonium chloride (National Pharmaceutical Group, China), potassium phosphate (National Pharmaceutical, China), and self-cultivated algae were added into it to control the concentrations of total nitrogen (TN), total phosphorus (TP), CODMn and Chl-a within a certain range, which were used for single-factor and response surface analysis with the purpose of determining the optimal process parameters
These results can be attributed to a reduction in the number of Hþ participating in the cathode reaction as pH increases; the reaction of formed by iron (Fe) oxidation to Fe2þ was inhibited, which affected the removal of CODMn (Huang et al )

Summary

Introduction

According to the latest survey, over 64% of the global lakes are eutrophic (Zhang et al ). The eutrophication of water bodies creates many problems: (1) the rapid propagation of algae leads to insufficient light in the water column and (2) a sharp drop in dissolved oxygen. These conditions can result in an unpleasant odor emanating from water that contains widespread deadly aquatic organisms and the occurrence of algal blooms or red tides (Gao et al ). These present enormous problems for the environment and human health. The treatment of eutrophic lake water is urgently needed

Methods

Results

Conclusion