Experimental Investigation into the Effect of Pyrolysis on Chemical Forms of Heavy Metals in Sewage Sludge Biochar (SSB), with Brief Ecological Risk Assessment

Li, Binbin; Ding, Shuiting; Fan, Haihong; Ren, Yu Qing

doi:10.3390/ma14020447

Cited by 30 publications

(17 citation statements)

References 21 publications

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“…The organic-bound state and the residual state are not easily absorbed by organisms in the environment and belong to the stable state. The exchangeable state, carbonate-bound state, and Fe-Mn oxide binding state are easily absorbed directly or indirectly and belong to the unstable state [20]. Many scholars have conducted research on heavy metal pollution using the Tessier sequential extraction method in samples of soils [21], sediments [22], and sewage sludge [15,23].…”

Section: Introductionmentioning

confidence: 99%

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan, China

You

Yan³

et al. 2021

Molecules

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In order to fully understand the morphological characteristics and pollution status of heavy metals in the dewatered sludge of Huainan Municipal sewage treatment plant, the physical and chemical properties were analyzed, and the content and occurrence forms of heavy metals (As, Cu, Zn, Pb, Cd, Cr, and Ni) in the sludge were studied using the geological accumulation method (Igeo), risk assessment coding method (RAC), and potential ecological risk index method to evaluate the ecological risk. The results showed that the municipal sludge in Huainan was rich in nutrients, with good prospects for agricultural utilization. There were differences in the morphological distributions of different heavy metals. The Igeo values for Ni, As, Cr, and Pb were below 0. The results of RAC indicated that the risk level of Cr in sludge was a low risk, and those of other heavy metals were moderate risks. The potential ecological risk of Cd had the highest potential ecological risk, and the other six metals were of low ecological risk. This conclusion can provide basic data and a theoretical reference for the comprehensive utilization of sludge in sewage treatment plants.

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Section: Introductionmentioning

confidence: 99%

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan, China

You

Yan³

et al. 2021

Molecules

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“…The potential risk of heavy metals in sewage sludge can be reduced by pyrolysis with variation of temperature [55]. The increase in temperature from 300 to 700 • C, increase the concentration of zinc (Zn), chromium (Cr), nickel (Ni), and copper (Cu), whereas the concentration of lead (Pb) and cadmium (Cd) is decreased when temperature increases from 600 to 700 • C. More research and experimental work is needed to completely analyze the heavy metal impact in biochar [56]. The microplastics are also removed at a temperature of 500 • C, which decreases the potential risk to the environment [57].…”

Section: Comparison Of Mass and Energy Balancesmentioning

confidence: 99%

Integrating Pyrolysis or Combustion with Scrubbing to Maximize the Nutrient and Energy Recovery from Municipal Sewage Sludge

Saud

Havukainen

Peltola³

et al. 2021

Recycling

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Based on mass and energy balance calculations, this work investigates the possibility of recovering heat and nutrients (nitrogen and phosphorus) from municipal sewage sludge using pyrolysis or combustion in combination with a gas scrubbing technology. Considering a wastewater treatment plant (WWTP) with 65,000 t/a of mechanically dewatered digestate (29% total solids), 550 t/a nitrogen and 500 t/a phosphorus were recovered from the 4900 t/a total nitrogen and 600 t/a total phosphorus that entered the WWTP. Overall, 3600 t/a (73%) of total nitrogen was lost to the air (as N2) and clean water, while 90 t/a (15%) of total phosphorus was lost to clean water released by the WWTP. Both in combustion and in pyrolysis, the nitrogen (3%) released within thermal drying fumes was recovered through condensate stripping and subsequent gas scrubbing, and together with the recovery of nitrogen from WWTP reject water, a total of 3500 t/a of ammonium sulfate fertilizer can be produced. Furthermore, 120 GWh/a of district heat and 9700 t/a of ash with 500 t/a phosphorus were obtained in the combustion scenario and 12,000 t/a of biochar with 500 t/a phosphorus was obtained in the pyrolysis scenario. The addition of a stripper and a scrubber for nitrogen recovery increases the total electricity consumption in both scenarios. According to an approximate cost estimation, combustion and pyrolysis require annual investment costs of 2–4 M EUR/a and 2–3 M EUR/a, respectively, while 3–5 M EUR/a and 3–3.5 M EUR/a will be generated as revenues from the products.

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“…However, the high heavy metal content greatly restricts utilization of sludge [23,24]. Thus, the quantity of heavy metals in sludge has always been a concern [25][26][27][28][29]. Azari et al [30] reported that compost concentrates or dilutes heavy metals in wastewater.…”

Section: Introductionmentioning

confidence: 99%

Heavy Metal Remediation in Sludge Compost: Recent Progress

Xiong¹,

Gao²,

Tu³

et al. 2022

Journal of Renewable Materials

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The safe and efficient disposal and utilization of sludge are major issues to be solved in solid waste treatment and environmental protection due to the complex characteristics of sludge and the low rate of innocuous treatments. Composting is a process of decomposing organic matter and transformed low-molecular organic acids into highmolecular humus substances under the action of microorganisms. Although land-use after composting has become an important direction for sludge treatment, heavy metal pollution is still the bottleneck problem restricting land use of sludge compost. Adding zeolite, hydroxyapatite, and other conditioning agents to the composting process affects the concentration or form of some heavy metals and effectively reduces the environmental risk. Lime and phosphorus modifiers change heavy metal speciation in samples, playing a role in decreasing biological availability and mobility. In this study, the effects of sludge composting treatment and conditioning agents on the concentrations and forms of heavy metals are reviewed. This review will provide a theoretical basis to treat heavy metals in sludge composting and lay the foundation for the land utilization and waste recycling of sludge. KEYWORDSSludge compost; heavy metal; conditioning agents; remediation Sludge treatment includes sanitary landfill, incineration, constructed wetland, composting and other methods. Sanitary landfill method has the advantages of simplicity, easy operation, low cost and strong adaptability. Although the most common method is sanitary landfilling in China, the future of sanitary landfilling is doubtful. The stability problem resulting from the poor physical nature of sludge and limited This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Experimental Investigation into the Effect of Pyrolysis on Chemical Forms of Heavy Metals in Sewage Sludge Biochar (SSB), with Brief Ecological Risk Assessment

Cited by 30 publications

References 21 publications

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan, China

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan, China

Integrating Pyrolysis or Combustion with Scrubbing to Maximize the Nutrient and Energy Recovery from Municipal Sewage Sludge

Heavy Metal Remediation in Sludge Compost: Recent Progress

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