Remediation Techniques for Cadmium-Contaminated Dredged River Sediments after Land Disposal

Changsong Zhang,Xiaoying Zhang,Zhenxue Dai,Xueke Zang,Ziqi Ma

doi:10.3390/su13116093

Abstract

This paper examines the remediation techniques of cadmium (Cd)-contaminated dredged river sediments after land disposal in a city in East China. Three remediation techniques, including stabilization, soil leaching, and phytoremediation, are compared by analyzing the performance of the techniques for Cd-contaminated soil remediation. The experimental results showed that the stabilization technique reduced the leaching rate of soil Cd from 33.3% to 14.3%, thus effectively reducing the biological toxicity of environmental Cd, but the total amount of Cd in soil did not decrease. Leaching soil with citric acid and oxalic acid achieved Cd removal rates of 90.1% and 92.4%, respectively. Compared with these two remediation techniques, phytoremediation was more efficient and easier to implement and had less secondary pollution, but it took more time, usually several years. In this study, these three remediation techniques were analyzed and discussed from technical, economic, and environmental safety perspectives by comprehensively considering the current status and future plans of the study site. Soil leaching was found to be the best technique for timely treatment of Cd contamination in dredged river sediments after land disposal.

Highlights

With recent social and economic developments, an increasing amount of industrial, agricultural, and domestic sewage waste has been regularly discharged into urban rivers, causing continuous river deterioration [1]
The dredged sediment disposal site was located at the urban-rural boundary area, where farmlands and rivers comprise most of the area, with fewer sensitive sites and low population density
If the dredged river sediments are not decontaminated in a timely manner, the current soil quality might not meet the functional requirements for subsequent agricultural land use, thereby causing environmental pollution incidents

Summary

Introduction

With recent social and economic developments, an increasing amount of industrial, agricultural, and domestic sewage waste has been regularly discharged into urban rivers, causing continuous river deterioration [1]. Dredging is an effective treatment method for urban rivers with fetid and dark-colored water. Dredged river sediments usually require further treatment, such as ex situ land or landfill disposal. The heavy metal Cd is one of the most common contaminants in river sediments [2,3,4]. This contaminant can affect the composition and structure of plant enzymes, thereby slowing plant growth and development, can accumulate in plants, and can even cause plants to be carcinogenic [10,11,12].

Methods

Results

Conclusion