Speciation Change of Flocs During Electrocoagulation for Wet Flue Gas Desulfurization Wastewater

Chen Zhou,Yunbo Xue,Xiangliang Liu,Jianwei Chen,Yu Peng,Wenyi Tan

doi:10.37358/rc.20.6.8198

Abstract

Wastewater produced from wet flue gas desulfurization (WFGD) process contains large amounts of suspended solids (SS), heavy metals and salinity. Compared to traditional chemical coagulation, electrocoagulation (EC) technology is a novel technology to remove these pollutants with lower O&M costs and simplified facilities. In order to achieve better EC effects, the speciation change of flocs generated from two kinds of sacrificed electrodes (e.g., Al and Fe) is investigated in various operation parameters. The results show that iron anode performed better compared to aluminium anode. At 20V of voltage and 6cm of electrode gap, the percentage of polymeric species of iron flocs can reach more than 50%. The significant domination of polymeric species under the optimal conditions during electrocoagution is responsible for the turbidity removal.

Highlights

In spite of various pollutants, such as SO2, CO2, NOx, particles mass and toxic metals, produced from coal combustion, coal-fired power plants are still the main power source in worldwide
With stricter regulations in environment adopted, the demand in zero or near-zero liquid discharge increases invests sharply and novel technology to treat Wet flue gas desulfurization (WFGD) wastewater are in need
Speciation determination Ferron-complexation timed spectrophotometry method was employed to analyses Al or Fe species for WFGD wastewater flocs obtained from EC experiments under operation conditions

Summary

Introduction

In spite of various pollutants, such as SO2, CO2, NOx, particles mass and toxic metals, produced from coal combustion, coal-fired power plants are still the main power source in worldwide. Many efforts have been made on the flue gas purification. Wet flue gas desulfurization (WFGD) is proved to be a practical technology in China, US, Japan, etc, due to its high efficiency and lower O&M costs. An amount of wastewater has to been discharged, in order to keep the limestone slurry as absorbent in reasonable ranges. The effluent from WFGD process contains complicated constitution, e.g., heavy metals, abundant Ca2+ or Mg2+ cations and SO42-, Cl- anions, etc. Traditional technology to treat WFGD wastewater includes chemical precipitation method, through which only heavy metals and suspended solid (SS) can be removed in three sequent tanks, but most of salinity are still present. With stricter regulations in environment adopted, the demand in zero or near-zero liquid discharge increases invests sharply and novel technology to treat WFGD wastewater are in need

Methods

Results

Conclusion