Leaching characteristic of potentially toxic metals of artificial soil made from municipal sludge compost

• Published in: Chemosphere (Oxford) 2021-05, Vol.270, p.128632, Article 128632
• Main Authors: Li, Feili, Shao, Luze, Chen, Yihao, Zhang, Gaoxiang, Nie, Qingting, Jin, Zanfang
• Format: Article
• Language: English
• Subjects: Composting; Heavy metal; Leaching index; Metals, Heavy - analysis; Municipal sludge waste; Sewage; Soil; Soil column experiment; Soil Pollutants - analysis; Water washing efficiency
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.128632

Landscaping of municipal sludge is a good choice to solve the sludge disposal problem, and EDTA treatment can effectively promote the uptake of heavy metals (HMs) by plants, but the heavy metal leaching process and its main control factors are still poorly understood during the sludge landscaping disposal. In this study, the migration behavior of HMs in artificial soil made from municipal sludge compost (MSC) were investigated using soil column experiments. After six leaching events for a total of one year’s rainfall, the average reduction percentage of total phosphorus, total nitrogen, organic matter in the MSC artificial soil were 13.4%, 10.1%, and 7.8%, respectively, while those of copper, lead, zinc, cadmium, nickel were 12.9%, 8.37%, 11.5%, 5.94%, and 10.7%, respectively. Treating ethylenediaminetetraacetic acid (EDTA) to the MSC artificial soil further enhanced the leach index of HMs to different degrees. HM concentration in leachate were increased with peak times postponed. Though EDTA treatment increased HM concentrations in subsoil, it did not change their water washing efficiency. The retention of HMs in subsoil was related to properties of local soil and its interaction with leachate. The potential ecological risk was of quite strong risk category in the MSC artificial soil and rapidly decreased from moderate to slight risk in subsoil. Cadmium was the main contribution accounting for 46%–93% of ecological risk. For landscaping applications, the composition of MSC artificial soil and local soil, as well as the capacity of the surrounding water, needs to be considered. [Display omitted] •The leaching behavior of heavy metals (HMs) in sludge compost column was studied.•Cu, Pb, Zn, Cd, Ni were decreased by 13%, 8.4%, 12%, 5.9%, and 11%, respectively.•Treating EDTA increased metal concentrations in leachates and delayed peak times.•The migration of HMs was related to N and P in the column rather than EDTA treating.