Abstract
Arsenic sulfide residue (ASR), a by-product from the treatment of arsenic-bearing acidic wastewater, is abundantly generated but not properly disposed of in China. The utilization of such high-content arsenic waste residue is limited by the market. The traditional methods of stabilization/solidification (S/S) by lime cement or iron salt have a large mass/volume addition, high dumping cost and secondary pollution risk. In this paper, hydrothermal technology was used to treat three kinds of ASRs obtained from different smelters to minimize waste. The leaching toxicity and chemical speciation of the generated products was also evaluated by TCLP and BCR analyses. It was found that the hydrothermal treatment could greatly reduce the volume and moisture content of the ASRs. TCLP tests showed that the leachability of arsenic and heavy metals significantly decreased after the treatment. According to the BCR analysis, most of the unstable As, Cd and Cr transformed into a residual fraction. Finally, XRD, SEM, Raman and XPS techniques were carried out to reveal the mechanism. As a result, hydrothermal treatment can efficiently achieve the dehydration, volume reduction and stabilization/solidification of ASRs.
Highlights
Arsenic-containing waste is widely produced due to anthropogenic activities [1,2,3,4]
Such wastewater is usually treated with sodium sulfide, sodium hydrosulfide or hydrogen sulfide to precipitate arsenic, and the deposition of arsenic sulfide residue (ASR) is engendered [15,16]
Arsenic sulfide residues used in the experiments were obtained from three nonferrous metal smelting companies located in Hubei, Shandong and Anhui, China, which were marked as HB-ASR, SD-ASR and AH-ASR, respectively
Summary
Arsenic-containing waste is widely produced due to anthropogenic activities [1,2,3,4]. Wasted electrolyte with a high concentration of arsenic is produced abundantly in copper and lead-zinc electrolyte processes [8,9]. There are many treatment methods for arsenic-containing wastewater, such as precipitation, adsorption, and biological methods [10,11,12,13,14]. Such wastewater is usually treated with sodium sulfide, sodium hydrosulfide or hydrogen sulfide to precipitate arsenic, and the deposition of arsenic sulfide residue (ASR) is engendered [15,16]
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