Migration and transformation of heavy metals during the microwave-assisted thermal hydrolysis of sewage sludge

Qiu, Chunsheng; Zheng, Jinxin; Wang, Chenchen; Wang, Bingbing; Liu, Nannan; Dong, Wang; Wang, Shaopo

doi:10.2166/wst.2021.272

Cited by 7 publications

(3 citation statements)

References 45 publications

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“…Previous study pointed out that the migration of heavy metals between solid-liquid phase mainly depended on the temperature. The percentage of all heavy metals (except Cu) in mobile (acid-soluble/exchangeable and reducible) forms decreased after microwave-assisted thermal hydrolysis treatment (Qiu et al 2021). The general conclusion was in line with the present study.…”

Section: Total Heavy Metal Contentsupporting

confidence: 92%

Impacts of wet thermal treatment on heavy metals speciation in contaminated waste activated sludge using a modified sequential extraction scheme

Zhang

Gan

Xie

et al. 2022

BioRes

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The mobility and the bioavailability of heavy metals in waste activated sludge were determined according to their total content and chemical speciation. A modified three-step sequential extraction procedure was used to determine the total content and metal speciation distribution pattern of various heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) pretreated at a temperature of 100 °C to 200 °C. It was found that the organics solubilization was enhanced at higher temperature, increased by 1.75, 183 and 3.03 folds over the soluble chemical oxygen demand (SCOD) at 100 °C. The total contents of Cd, Pb and Zn exceeded the threshold value established in GB/T standard 23486 (2009), as a function of pH, due to the pollution from the local nonferrous metals industry. For most cases, the impacts of thermal pretreatment on the species distribution were limited and obscure. Cr was the only element showing a potential risk of metal mobilization, such that its residual fraction shifted towards oxidizable fraction at higher treatment temperature. The speciation distribution pattern of Ni, Cr, Cu, and Zn showed potential risks of contamination due to their bioavailability, mobility, or toxicity.

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Section: Total Heavy Metal Contentsupporting

confidence: 92%

Impacts of wet thermal treatment on heavy metals speciation in contaminated waste activated sludge using a modified sequential extraction scheme

Zhang

Gan

Xie

et al. 2022

BioRes

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“…Previous studies found that a great proportion of heavy metals remained in biochar after pyrolysis treatment, but partial heavy metals could be transferred to the liquid product (bio-oil) or gas phase (Lu et al 2015;Qiu et al 2021), resulting in the content reduction of Ni. Meanwhile, the concentrations of Cr in BC500, BC600, and BC700 increased by 20.35%, 15.24% and 6.95%, respectively, compared with the raw material.…”

Section: Results Of Ftir Analysismentioning

confidence: 99%

Migration and transformation of heavy metals in boxwood sawdust biochar derived under different pyrolysis temperatures

Ma,

Qiu,

Liu

et al. 2023

Preprint

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In this study, biochar was prepared from boxwood sawdust under oxygen-limited conditions at 300, 400, 500, 600, 700 and 800 oC, respectively. The effects of different pyrolysis temperatures on the biochar physicochemical properties, migration and transformation of heavy metals (Cu, As, Ni, Cr and Pb) in the derived biochar were investigated. The results showed that the yield decreased, the ash content and pH of derived biochar increased with the increasing temperatures. The specific surface area of biochar was maintained at about 300 m2/g when the pyrolysis temperature was over 600 oC, and the highest total pore volume reached 2.0956 cm3/g− 1 at 800 oC. The concentrations of Cu, As, Cr and Pb increased by 20.35%-202.37% after pyrolysis. Meanwhile, heavy metals in bioavailable faction were partially transformed into relatively stable fractions with the increasing temperature. Furthermore, the potential environmental risks of heavy metals were reduced in the biochars derived at high temperature.

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“…8). The treatment was efficient because acid hydrolysis releases TMs in mobile forms [56], which presumably chelate readily with EDTA. The extended time of acid hydrolysis (1 h at pH 3) further increased the TMs removal efficiency to 91%-Pb, 73%-Zn, 3%-Cu, 63%-Mn, and 73%-Fe (Treatment No.…”

Section: Selection Of the Most Efficient Treatment To Remove Tms From Ssmentioning

confidence: 99%

Removal of Toxic Metals from Sewage Sludge by Acid Hydrolysis Coupled with EDTA Washing in a Closed-Loop Process

Arteaga

Zupanc

Dular

et al. 2023

IJERPH

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Contamination with toxic metals prevents the use of sewage sludge (SS) as a soil fertilizer. Hydrodynamic cavitation, thermal microwaving, microwave-assisted alkaline, and acid hydrolysis coupled with ethylenediaminetetraacetate (EDTA) washing were tested as a method to remove toxic metals from SS. Acid hydrolysis coupled with EDTA washing was most effective and was used in a closed-loop process based on ReSoil technology. EDTA and process solutions were recycled at a pH gradient of 12.5–2, which was imposed by the addition of quicklime (CaO) and H2SO4. An average of 78%-Pb, 76%-Zn, 1%-Cu, and 17%-Cr were removed from SS in five consecutive batches. No wastewater was generated, only solid waste (40%). The EDTA lost in the process (42%) was resupplied in each batch. In a series of batches, the process solutions retained metal removal efficiency and quality. The treatment removed 70% and 23% of P and N, respectively, from SS and increased the leachability of Zn, Cu, Mn, and Fe in the washed SS by 11.7, 6.8, 1.4, and 5.2 times, respectively. Acid hydrolysis coupled with EDTA washing proved to be a technically feasible, closed-loop process but needs further development to reduce reagent, material, and nutrient loss and to reduce toxic emissions from the washed sludge.

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Migration and transformation of heavy metals during the microwave-assisted thermal hydrolysis of sewage sludge

Cited by 7 publications

References 45 publications

Impacts of wet thermal treatment on heavy metals speciation in contaminated waste activated sludge using a modified sequential extraction scheme

Impacts of wet thermal treatment on heavy metals speciation in contaminated waste activated sludge using a modified sequential extraction scheme

Migration and transformation of heavy metals in boxwood sawdust biochar derived under different pyrolysis temperatures

Removal of Toxic Metals from Sewage Sludge by Acid Hydrolysis Coupled with EDTA Washing in a Closed-Loop Process

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