Migration and Conversion of Phosphorus in Hydrothermal Carbonization of Municipal Sludge with Hydrochloric Acid

Yang Xue, Zhipu Wang (), Yue Wu, Ruiqi Wu and Fengtao Zhao
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Yang Xue: Faculty of Engineering, China University of Petroleum-Beijing at Karamay, Karamay 834000, China
Zhipu Wang: Faculty of Engineering, China University of Petroleum-Beijing at Karamay, Karamay 834000, China
Yue Wu: Karamay Shuntong Environmental Technology Co., Ltd., Karamay 834000, China
Ruiqi Wu: Xinjiang Academy of Environmental Protection Science, Urumqi 830011, China
Fengtao Zhao: Xinjiang Academy of Environmental Protection Science, Urumqi 830011, China

Sustainability, 2023, vol. 15, issue 8, 1-11

Abstract: Phosphate ore is a non-renewable resource, so finding a replacement is necessary. Municipal sludge has significant recycling potential because of its high phosphorus content and large discharge characteristics. The migration and transformation of phosphorus in municipal sludge treated with different concentrations of HCl were studied using the standards, measurements, and testing phosphorus extraction protocol from two aspects: phosphorus complexation and mineral form. After the hydrothermal carbonization treatment without HCl, the hydrochar retained 99.7% of phosphorus in the sludge, and the organophosphorus percentage was about 30%. In the hydrothermal carbonization treatment with the addition of 0.5–2.5% HCl, the phosphorus content in the hydrochar decreased gradually from 99.5% (46.18 mg/g) to 91.8% (64.17 mg/g) that of the original sludge, and the proportion of non-apatite inorganic phosphorus increased from 34% to 94%. Hydrochloric acid provides a low-pH environment and promotes the dissolution of calcium-related phosphorus precipitates and enhances the dehydration reaction. This study provides technical support for the recovery of phosphorus resources from municipal sludge.

Keywords: municipal sludge; hydrothermal carbonization; phosphorus; hydrochloric acid; migration and transformation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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