Effects of co-pyrolysis of rice husk and sewage sludge on the bioavailability and environmental risks of Pb and Cd

Yang, Yan; Cui, Min-Hua; Guo, Jenhwa; Du, Jingjing; Zheng, Zhifeng; Liu, He

doi:10.1080/09593330.2019.1701562

Cited by 16 publications

(23 citation statements)

References 40 publications

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“…Recent research has shown that when the temperature higher than 600 °C, for instance, cadmium (Cd), can be volatilized into syngas and bio-oil. However, following the pyrolysis of sewage sludge at a moderate temperature, over 90% of other heavy metals will be remained in the biochar (Jin et al 2017;Yang et al 2021;Wang et al 2022). Therefore, pyrolysis conditions, including temperature and atmosphere, play an important role in determining the distribution of heavy metals.…”

Section: Factors Affecting Heavy Metals Stabilization In Biocharmentioning

confidence: 99%

“…According to the findings of He et al (2010), pyrolysis temperatures higher than 350 °C result in better stability of trace heavy metals such as Cd, Pb, Zn, and Cu (He et al 2010). The environmental damage and toxicity of metals in the co-pyrolyzed biochar decreased further, and co-pyrolysis at 600 °C was found to be suitable for sewage sludge nutrient recycling (Jin et al 2017;Yang et al 2021). High pyrolysis temperatures promote the creation of more permanent aromatic bonds and the elimination of transitory aliphatic bonds (Gondek et al 2014).…”

Section: Effect Of Pyrolysis Temperaturementioning

confidence: 99%

“…Another important factor affecting biochar quality is the sample residence time; long residence periods during copyrolysis of sewage sludge usually have a positive impact on heavy metal immobilization, resulting in a sufficient reduction of the possible damage to the environment (Wang et al 2019a). In the meantime, co-pyrolysis will change the bioavailability of heavy metals into stable compounds, leading to a substantial reduction in direct toxicity of biochar (Wang et al 2019a;Yang et al 2021). However, very long residence times will reduce the surface area because of the pore structure destruction (Wang et al 2019a).…”

Section: Effect Of Pyrolysis Temperaturementioning

confidence: 99%

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Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

et al. 2022

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The huge amounts of sewage sludge produced by municipal wastewater treatment plants induce major environmental and economical issues, calling for advanced disposal methods. Traditional methods for sewage sludge disposal increase greenhouse gas emissions and pollution. Moreover, biochar created from sewage sludge often cannot be used directly in soil applications due to elevated levels of heavy metals and other toxic compounds, which alter soil biota and earthworms. This has limited the application of sewage sludge-derived biochar as a fertilizer. Here, we review biomass and sewage sludge co-pyrolysis with a focus on the stabilization of heavy metals and toxicity reduction of the sludge-derived biochar. We observed that co-pyrolyzing sewage sludge with biomass materials reduced heavy metal concentrations and decreased the environmental risk of sludge-derived biochar by up to 93%. Biochar produced from sewage sludge and biomass co-pyrolysis could enhance the reproduction stimulation of soil biota by 20‒98%. Heavy metals immobilization and transformation are controlled by the co-feed material mixing ratio, pyrolysis temperature, and pyrolysis atmosphere.

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Section: Factors Affecting Heavy Metals Stabilization In Biocharmentioning

confidence: 99%

Section: Effect Of Pyrolysis Temperaturementioning

confidence: 99%

Section: Effect Of Pyrolysis Temperaturementioning

confidence: 99%

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Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

et al. 2022

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“…However, the porosity, specific surface area, and adsorption capacity of the adsorbents produced by pyrolysis of sewage sludge are far behind those of commercial activated carbon adsorbents. In order to improve the adsorption performance of sludge adsorbents, some scholars used other biomass for co-pyrolysis such as cotton stalks (Wang et al, 2019), rice husks (Yang et al, 2010), and bagasse (Lin et al, 2017). Some scholars have tried to add chemical agents for activation during the pyrolysis process.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Adsorbents by Pyrolysis of Sludge Mixed With Steel Slag and Study on Adsorption of Chromium Ions in Water

Zhou

et al. 2022

Front. Energy Res.

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In this study, the dewatered sludge from the sewage plant and the open-hearth steel slag of the steel plant are used as raw materials. As two wastes, they were mixed and pyrolyzed to prepare a composite absorbent. Further, the adsorption mechanism of the adsorbent to chromium ions in the sewage is explored. The pyrolysis reaction behavior of sludge mixed with steel slag was studied by the thermogravimetric analysis technology. SEM, BET, and XPS were used to analyze the specific surface area, pore size distribution, and pore structure characteristics of pyrolysis products, respectively. Moreover, a comprehensive analysis of the adsorbent was carried out for the adsorption mechanism of hexavalent chromium ions. The results show that the addition of steel slag promotes the pyrolysis of the sludge in each stage. When the content of steel slag is 80%, the increases of reaction rate are the most obvious with the largest increase of weight loss rate in each stage. The SEM results show that the enrichment of sludge on metal oxides is enhanced in the high-temperature range (600–700°C). Besides, when the content of steel slag is 40–60%, the mixture’s growth rate of the specific surface area can reach 600% and the growth rate of total pore volume can reach 350% (the situations of sludge as the baseline). Regarding the measurement of Cr(VI), the adsorption rate of the steel-slag solution is 50.93% and that of the sludge solution is 69%. However, the adsorption rate can be increased to 95% when the steel slag and sludge were mixed as an adsorption solution. In conclusion, the adsorption mechanism of Cr(VI) by additives is controlled by both physical and chemical processes. The present study provides a theoretical basis and technical support for the scientific and reasonable utilization of sludge and steel slag.

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“…Apart from other pollutants, the presence of heavy metals (HMs) in the SS composition is unfavorable and excludes this waste from applications in the natural environment. This is why SS needs to be subjected to systematic monitoring and controlling in the terms of HM contents [9]. Unfortunately, the legal requirements concern only the total content of heavy metals.…”

Section: Introductionmentioning

confidence: 99%

Changes in lead and chromium contents in sewage sludge evaluated using both single extractants and sequential method

Jakubus

2020

Environmental Pollutants and Bioavailability

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The aim of this study was to evaluate changes in lead and chromium amounts in sequentially separated fractions and available forms of four sewage sludge (SS). Lead and chromium sequential extraction in SS was performed using BCR method. Single extractants were used to assay available and bioavailable forms of metals. It was found that Pb and Cr were detected in the largest amounts in organic forms, while the lowest levels were recorded for exchangeable ones. Sewage sludges from the small installations contained significantly lower amounts of metals (both available, bioavailable and sequentially separated fractions of sewage sludge) in comparison with those originating from the large treatment installations. Generally amounts of metals detected in sewage sludge were small in the years of this study, which should be considered a positive trend. Additionally, the bioavailability index (φ) and risk assessment code (RAC) indicated no negative impact of metals contained in the analysed SS on the soil environment.

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Effects of co-pyrolysis of rice husk and sewage sludge on the bioavailability and environmental risks of Pb and Cd

Cited by 16 publications

References 40 publications

Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

Preparation of Adsorbents by Pyrolysis of Sludge Mixed With Steel Slag and Study on Adsorption of Chromium Ions in Water

Changes in lead and chromium contents in sewage sludge evaluated using both single extractants and sequential method

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