Feedwater pH affects phosphorus transformation during hydrothermal carbonization of sewage sludge

Wang, Tao; Zhai, Yunbo; Zhu, Yun; Peng, Chuan; Wang, Tengfei; Xu, Bibo; Li, Caiting; Zeng, Guangming

doi:10.1016/j.biortech.2017.08.114

Cited by 119 publications

(87 citation statements)

References 33 publications

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“…Very small amounts of P, Ca, Al, Fe and Mn were detected to be released into process waters (<0.6%) while the majority of them were accumulated in the hydrochar, and the extent of this kind of accumulation increased with the increase of treatment temperature. Performing HTC on ADSS, Wang et al [ 78 ] reported that P was mostly accumulated in the hydrochar, which agreed with the results found by Heilmann et al [ 27 ], demonstrating that the vast majority of P forms could be recovered from hydrochar, due to precipitation of phosphate salts. On the contrary, in their study, Aragón-briceño et al [ 34 ] reported that P was prevalently in the process waters rather than hydrochar, mainly in the form of inorganic P rather than organic P. The different fates of P during HTC, both extraction and immobilization in hydrochar, depend on HTC conditions, feedstock type and the content of inorganics, such as Al, Ca, Fe and Mg, in the feedstock [ 88 , 91 ].…”

Section: Hydrothermal Carbonization Process Water Characterizationsupporting

confidence: 80%

“…Stemann et al [ 77 ] showed that by process water recirculation, organic acids in the liquid phase catalyze HTC reactions. NaOH, Ca(OH) 2 are used as bases [ 72 , 78 ], while NaCl and CaCl 2 [ 72 ] and Ca propionate, Ca acetate, Mg acetate, Ca lactate, Li chloride, Ca chloride and Ca formate are commonly used as salts [ 74 ]. CaO additive has been employed in near-critical water to act as CO 2 absorber via carbonation [ 59 ], while zeolite has been used as a catalyst in the HTC process, increasing the energy and carbon recovery in hydrochar from digestate [ 79 ].…”

Section: Hydrothermal Carbonizationmentioning

confidence: 99%

“…The effect of different feedwater pH values on the P transformation in hydrochar during the HTC of the ADSS has been studied by Wang et al [ 78 ]. Their results provide a theoretical basis for selecting appropriate methods and strategies for improving the performance of P recycling and reclamation from similar solid waste materials.…”

Section: Hydrothermal Carbonization Process Water Characterizationmentioning

confidence: 99%

See 2 more Smart Citations

Process Waters from Hydrothermal Carbonization of Sludge: Characteristics and Possible Valorization Pathways

Langone

Basso

2020

IJERPH

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Hydrothermal carbonization (HTC) is an innovative process capable of converting wet biodegradable residues into value-added materials, such as hydrochar. HTC has been studied for decades, however, a lack of detailed information on the production and composition of the process water has been highlighted by several authors. In this paper the state of the art of the knowledge on this by-product is analyzed, with attention to HTC applied to municipal and agro-industrial anaerobic digestion digestate. The chemical and physical characteristics of the process water obtained at different HTC conditions are compared along with pH, color, organic matter, nutrients, heavy metals and toxic compounds. The possibility of recovering nutrients and other valorization pathways is analyzed and technical feasibility constraints are reported. Finally, the paper describes the main companies which are investing actively in proposing HTC technology towards improving an effective process water valorization.

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Section: Hydrothermal Carbonization Process Water Characterizationsupporting

confidence: 80%

Section: Hydrothermal Carbonizationmentioning

confidence: 99%

Section: Hydrothermal Carbonization Process Water Characterizationmentioning

confidence: 99%

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Process Waters from Hydrothermal Carbonization of Sludge: Characteristics and Possible Valorization Pathways

Langone

Basso

2020

IJERPH

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“…These could be the reasons for the increase in the concentration of phosphorus. Wang et al [24] reported significant accumulation of phosphorus in hydrochar obtained from HTC of sewage sludge. The carbon to nitrogen ratio (C/N) was found to increase with an increase in temperature, with a maximum of 13.1 obtained for hydrochar obtained from treatment at 220 • C and 30 min residence time, which represents an increase of 60% as compared to raw biosolid.…”

Section: Physiochemical Properties Of Hydrocharmentioning

confidence: 99%

Hydrothermal Carbonization of Biosolids from Waste Water Treatment Plant

et al. 2018

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The high moisture content of biosolid from a wastewater treatment plant limits its use for agriculture and energy applications. This limitation could be obviated by hydrothermal carbonization, which requires less energy compared to other thermochemical treatment processes, and results in stabilized solid hydrochar product. The present study examined this option by hydrothermally treating the biosolid at three temperatures (180, 200 and 220 °C) for 30 min, and at 200 °C for 15, 30 and 60 min. An increase of 50% in the heating value of the biosolid was obtained after this carbonization. A reduction in the nitrogen concentration in hydrochar was noted with an increase in phosphorus concentration, but potassium concentration remained largely unchanged. Additionally, the carbon to nitrogen ratio in the hydrochar product was higher than the biosolid that makes it suitable for agriculture applications. The chemical oxygen demand of the process water was in the range of 83,000 to 96,000 mg/L. The study thus provides insight into high-value products that can be generated by the hydrothermal carbonization of biosolids.

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“…The following flotation treatment at a pH of 10 to this portion revealed that an additional enrichment of 19% on relative basis of P2O5 content was achieved in the froth compared with the tailings. The results showed that using a heating treatment could increase phosphorus recovery from sewage sludge ash by mineral processing methods Wang, Zhai et al (2017). studied the effect of feedwater pH between 3 and 11 on phosphorus transformation during the hydrothermal carbonization process of sewage sludge at a temperature range of 200-260 °C.…”

mentioning

confidence: 99%