Passivating Effect of Dewatered Sludge and Biochar on As-Contaminated Soil

Abstract

The pollution caused by As in soil menaces the health of humans. There are characteristics of waste utilization, low cost, and a wide range of materials by using dewatered sludge as the main component of soil repair agents. In this paper, dewatered sludge and biochar were used as repair agents for As pollution, which were rarely reported, and the related passivation experiments were carried out. Through the analysis of experimental data of the basic physical and chemical properties of contaminated soil, various characteristics of repair agent and As morphology were obtained, and the applicability and passivation effect of dewatered sludge-biochar compound repair agent and dewatered sludge as an individual repair agent on passivation of As pollution in soil was discussed. By comparing different passivation effects, the repairing effect increases with time, and the optimal repair time was 40 days; in the set experiment group, the best passivation effect of the individual repair agent was the S3 (dry sludge accounting for 20% of soil samples) experimental group, and the best effect of the compound repair agent was the S + B3 (dry sludge and biochar accounting for 10% and 2% of soil samples, respectively) group. As a repair agent, the dewatered sludge-biochar compound repair agent can be used to repair As-contaminated soil, which provides a new method for the recycling and waste utilization of dewatered sludge.