Combined filtration and oxalic acid leaching for recovering phosphorus from hydrothermally carbonized sewage sludge

Waldmüller, Wolfgang; Herdzik, S.; Gaderer, Matthias

doi:10.1016/j.jece.2020.104800

Cited by 12 publications

(4 citation statements)

References 42 publications

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“…Zinc resources are nonrenewable and are becoming increasingly scarce with continuous exploitation and use. − Consequently, low-grade zinc ores and zinc-containing wastes are receiving increased attention, with researchers exploring ways to extract valuable metals from them. , Iron slag, a solid waste produced during the purification and impurity removal stage of the wet zinc smelting process, is of particular interest. Wet zinc smelting, which accounts for over 85% of the world’s zinc production, has become the dominant method for zinc smelting. − Iron slag, with its high iron and zinc content, has significant potential for comprehensive recovery and utilization. , However, as a viscous material, iron slag retains a high moisture content of over 40% even after treatment with a plate and frame filter press. − This high moisture content can cause slag dampness and stickiness, leading to clumping that severely affects the feeding systems of rotary kilns and smelting furnaces. , This can result in furnace feed disruptions, large fluctuations in furnace conditions, a decrease in zinc oxide quality, and increased labor intensity for workers. , Moreover, the high moisture content of iron slag makes subsequent dehydration processes difficult and energy-intensive. , …”

Section: Introductionmentioning

confidence: 99%

“… 6 − 8 Iron slag, with its high iron and zinc content, has significant potential for comprehensive recovery and utilization. 9 , 10 However, as a viscous material, iron slag retains a high moisture content of over 40% even after treatment with a plate and frame filter press. 11 − 13 This high moisture content can cause slag dampness and stickiness, leading to clumping that severely affects the feeding systems of rotary kilns and smelting furnaces.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves

Cheng,

Dai,

Zhang

et al. 2024

ACS Omega

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This study investigates the impact of ultrasonic treatment on the drying kinetics of zinc smelting iron slag. Through the Arrhenius equation, it was found that the reaction order of zinc smelting iron slag remains constant at 1/2 before and after ultrasonic treatment, indicating a proportional relationship between the reaction rate and the square root of the reactant concentration. Despite the increased drying rate of the iron slag due to ultrasonic pretreatment, the reaction order remains at 1/2. Additionally, it was observed that the drying kinetics of untreated iron slag aligns with the Wang and Singh model, while the drying kinetics of ultrasonically pretreated iron slag fits the Page model. The Page model facilitates the prediction of drying rate and drying time for ultrasonically pretreated iron slag, enabling the optimization of the drying process, enhancing efficiency, and comparing drying performance under different conditions. Using ultrasonic pretreatment, the subsequent drying process of iron slag can significantly shorten the time and save energy. These findings provide essential theoretical foundations for optimizing the drying process of zinc smelting iron slag.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves

Cheng,

Dai,

Zhang

et al. 2024

ACS Omega

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“…HTC treatment allows the organic matter in the feedstock to be dissolved in the liquid product (process water, PW), thereby effectively reducing the sludge volume; moreover, this process leads to PW, which contains a considerable amount of nutrients [15]. Simultaneously, a carbon-rich solid is generated, which is called hydrochar, and its main potential applications include solid fuel and soil remediation material [16,17]. By adjusting the hold time, temperature, and other process parameters, these reactions can be controlled to further influence the product properties.…”

Section: Introductionmentioning

confidence: 99%

Hydrochloric Acid Catalyzed Hydrothermal Treatment to Recover Phosphorus from Municipal Sludge

Liu,

Xue,

Zhai

et al. 2024

Catalysts

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Resource utilization of sludge is critical because traditional sludge treatment methods cause a large amount of nutrient loss. This study investigated the impact of hydrochloric acid quantity, reaction temperature, and time on phosphorus release and migration from municipal sludge during hydrothermal treatment and designed a sludge disposal method for the recovery and utilization of phosphorus resources. We know that hydrochloric acid destroys the complexation of calcium and phosphorus precipitates, leading to the selective transfer of phosphorus to the liquid phase, and that the addition of 1–5% hydrochloric acid corresponds to a phosphorus extraction rate in the range of 0.3–98%. When hydrochloric acid is added, a change in temperature and reaction time has a negligible effect on phosphorus. Phosphorus can be recovered using the liquid product obtained under the optimal hydrothermal reaction conditions (adding 5% HCl at 205 °C for 30 min). After adjusting the pH value and adding the magnesium source, struvite (MgNH4PO4·6H2O) can be precipitated quickly and with high purity. At a cost of USD 27.8/ton of sludge, this method can recover 94% of the phosphorus in the sludge, and the bioavailable phosphorus ratio of the product is 93%, therefore, providing an important alternative to existing phosphorus recovery technologies.

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“…Similarly, Waldmuller et al (2021) employed a combined treatment of filtration and oxalic acid leaching to recover P from hydrochar. Following pressure filtration, the authors managed to leach 41-83% of phosphate and sodium from the hydrochar, respectively, while iron, calcium, and other inorganics were precipitated to a lesser extent as oxalates [6]. Obtaining two high-added value products from HTC of sewage sludge has been shown to be one of the sustainable future strategies for sewage sludge management [7].…”

Section: Introductionmentioning

confidence: 99%

Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge

et al. 2021

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Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014–2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters ((higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN1 (based on C, H, O content) exhibited HHV predicting performance with R2 = 0.974, another model, NN2, was also able to predict HHV with R2 = 0.936 using only C and H as input. Moreover, the inverse model of NN3 (based on H, O content, and HHV) could predict C content with an R2 of 0.939.

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Combined filtration and oxalic acid leaching for recovering phosphorus from hydrothermally carbonized sewage sludge

Cited by 12 publications

References 42 publications

Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves

Study on the Drying Kinetics of Zinc Smelting Iron Slag Assisted by Ultrasonic Waves

Hydrochloric Acid Catalyzed Hydrothermal Treatment to Recover Phosphorus from Municipal Sludge

Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge

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