Abstract
An incubation experiment was conducted to determine the effects of nanoscale drinking water treatment residuals (nWTRs) on arsenic (As) fractionation and speciation in agricultural soil amended with biosolids. The soils were treated with biosolids of 3% (w/w), along with nWTR application rates of 0, 0.25, 0.50, or 1.00% (w/w). The results revealed that the As adsorption rate increased with increasing the As treatment level from 50 to 800 mg/L. The maximum efficiency of As adsorption was 95%–98% in the soil treated with nWTRs of 1%, while the least As adsorption was 53%–91% in the soil treated with nWTRs of 0.25%. The overall As bioavailability in the biosolids-amended soil followed a descending order of nWTRs treatment: (0%) > 0.25% nWTRs, >0.50% nWTRs, and >1% nWTRs. The addition of nWTRs significantly changed As speciation in biosolids-amended soil. The X-ray absorption near-edge structure spectroscopy (XANES) and MINEQL+4.6 analyses showed that most of As was in a oxidized form of As5+ that likely incorporated in As pentoxide, and thus, with low mobility, bioavailability, and toxicity. This study demonstrated that nWTRs were effective in adsorbing and immobilizing As in biosolids-amended agricultural soils by forming stable As-nWTR surface complexes.
Highlights
Arsenic (As) is a common contaminant in soils and waters
Differences in As sorption capacity were observed between different nanoscale drinking water treatment residuals (nWTRs)-application rates of 0.25, 0.50, and
The initial As concentration significantly affected the As adsorption to the soil treated with both biosolids and nWTRs
Summary
Arsenic (As) is a common contaminant in soils and waters. The large environmental input of As has mainly been related to anthropogenic activities including those originated from agricultural land application of fertilizers, pesticides, and/or biosolids (treated sewage-sludge originating from municipal wastewater treatment plants). As remediation technologies have been developed to reduce As contents or limit As bioavailability in the environment [1,2,3,4]. Arsenic remediation can be expensive [5] and have application limitations [6,7]. In recent years some “green” remediation techniques have been proposed, and different As-adsorbents including nanomaterials have been evaluated to reduce As bioavailability in soil and water [8,9,10]
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