The Improvement Effects of Different Treatment Methods of Soil Wastewater Washing on Environmental Pollution

Linjie Zhan,Minxian Chen

doi:10.3390/w12092329

Linjie Zhan, Minxian Chen

Open Access

https://doi.org/10.3390/w12092329

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Journal: Water	Publication Date: Aug 19, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: University of Macau, Henan University of Technology

Abstract

This paper focus on how to treat the wastewater after soil washing since water pollution is a severe threat to the water security of China. Ca (OH)2 and two kinds of biochars (biochar and ZnCl2 modified biochar) were tested to treat the waste FeCl3 washing effluent. Two kinds of biochars (biochar and ZnCl2-modified biochar) were prepared from maize straws. Soil samples were collected near a smelter for adsorption experiments. ICP-OES was used to determine the concentration of metal ions in the samples, as well as calculating their adsorption capacity and removal rate. As to Ca(OH)2 treatment, the maximum removal rates of Cd, Pb, Cu, and Zn could exceed 99%, and the concentrations of Cd, Pb, Cu, and Zn in solution could reduce to 0.08, 0.018, 0.15, 0.44 mg/dm3, respectively. However, both of the two biochars had relatively low removal rates compared with Ca (OH)2 treatment. The wastewater shows significantly lower environmental implications after the two treatments, and the lime precipitation method has better effects than biochar adsorption. The activated carbon adsorption method discussed can significantly improve the environmental pollution caused by soil washing wastewater, which is suitable for environmental treatment projects.

Highlights

Soil heavy metal pollution has been a severe problem, along with economic growth and rapid industrialization
The activated carbon adsorption method discussed can significantly improve the environmental pollution caused by soil washing wastewater, which is suitable for environmental treatment projects
Had some unsaturated carbon bonds, carboxyl groups, hydroxyl groups, and other groups that were substituted with metal ions; they could bind to metal ions in the solution to remove the heavy metal pollutants in industrial wastewater

Summary

Introduction

Soil heavy metal pollution has been a severe problem, along with economic growth and rapid industrialization. According to a report by the Chinese government made in 2014, about 13% of farmland soils were polluted by heavy metals metalloids [1] in the soil survey. A large body of research in the remediation of heavy metal polluted soil has been conducted. Soil washing was one of the most effective means among the different treatments of the heavy metal polluted soil. FeCl3 is a popular soil washing leachate [7], and it has already been applied in some countries to remediate soil contaminated by certain heavy metals, such as Cd and Pb [8,9]

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