scholarly journals Process Water Recirculation during Hydrothermal Carbonization of Waste Biomass: Current Knowledge and Challenges

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2962
Author(s):  
Antonio Picone ◽  
Maurizio Volpe ◽  
Antonio Messineo
Keyword(s):  
Current Knowledge ◽  
Hydrothermal Process ◽  
Hydrothermal Carbonization ◽  
Process Water ◽  
Residual Fraction ◽  
Waste Biomass ◽  
Carbon Recovery ◽  
Thermochemical Processing ◽  
Water Recirculation ◽  
Additional Water

Hydrothermal carbonization (HTC) is considered as an efficient and constantly expanding eco-friendly methodology for thermochemical processing of high moisture waste biomass into solid biofuels and valuable carbonaceous materials. However, during HTC, a considerable amount of organics, initially present in the feedstock, are found in the process water (PW). PW recirculation is attracting an increasing interest in the hydrothermal process field as it offers the potential to increase the carbon recovery yield while increasing hydrochar energy density. PW recirculation can be considered as a viable method for the valorization and reuse of the HTC aqueous phase, both by reducing the amount of additional water used for the process and maximizing energy recovery from the HTC liquid residual fraction. In this work, the effects of PW recirculation, for different starting waste biomasses, on the properties of hydrochars and liquid phase products are reviewed. The mechanism of production and evolution of hydrochar during recirculation steps are discussed, highlighting the possible pathways which could enhance energy and carbon recovery. Challenges of PW recirculation are presented and research opportunities proposed, showing how PW recirculation could increase the economic viability of the process while contributing in mitigating environmental impacts.

Thermal behavior of hydrochar from co-hydrothermal carbonization of swine manure and sawdust: effect of process water recirculation

2019 ◽  
Vol 3 (9) ◽  
pp. 2329-2336 ◽  
Author(s):  
Qianqian Lang ◽  
Hainan Luo ◽  
Yi Li ◽  
Dong Li ◽  
Zhengang Liu ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Swine Manure ◽  
Hydrothermal Carbonization ◽  
Process Water ◽  
Combustion Behavior ◽  
Water Recirculation

Process water recirculation during co-HTC of swine manure and sawdust changed the combustion behavior of hydrochar.

Effects of process water recirculation on solid and liquid products from hydrothermal carbonization of Laminaria

2019 ◽  
Vol 292 ◽  
pp. 121996 ◽  
Author(s):  
Fengbo Wang ◽  
Jing Wang ◽  
Chen Gu ◽  
Ying Han ◽  
Shuaijun Zan ◽  
...  
Keyword(s):  
Hydrothermal Carbonization ◽  
Process Water ◽  
Liquid Products ◽  
Water Recirculation

scholarly journals Process Water Recirculation During Hydrothermal Carbonization as a Promising Process Step Towards the Production of Nitrogen-Doped Carbonaceous Materials

2021 ◽  
Author(s):  
Wüst Dominik ◽  
Arauzo Pablo ◽  
Habicht Sonja ◽  
Cazaña Fernando ◽  
Fiori Luca ◽  
...  
Keyword(s):  
Hydrothermal Carbonization ◽  
Added Value ◽  
Process Water ◽  
Carbonaceous Materials ◽  
Process Step ◽  
Nitrogen Doped ◽  
Physico Chemical ◽  
Spent Grains ◽  
Liquid Products ◽  
Water Recirculation

AbstractHydrothermal Carbonization (HTC) refers to the conversion of biogenic wastes into char-like solids with promising perspectives for application, but a process water (PW) results which is difficult to dispose untreated. Thus, a biorefinery approach including one or two recirculation steps with the additional objective of improving the physico-chemical characteristics of the solid was performed in this study. During HTC, constitutive molecules such as saccharides, proteins and lignin of Brewer’s Spent Grains decompose into hundreds of organic compounds, following complex reactions. To get deeper insights a combination of proximate, ultimate and structural analysis for solid products as well as liquid chromatography for liquid products were the choice. The main reactions could be identified by key compounds of low and high molecular weight resulting from hydrolysis, dehydration, decarboxylation, deamination as well as amide formation and condensation reactions. Their intensity was influenced by the feedwater pH and reaction temperature. Via reactions of Maillard character up to around 90% of the dissolved nitrogen of the recirculated process water at 200, 220 and 240 °C result in the formation of nitrogen containing heterocycles or rather Quartnernary nitrogen incorporated into the hydrochar (HC). Thus, already one recirculation step during HTC at 240 °C promises the fabrication of high added-value materials, i.e. nitrogen doped carbonaceous materials. Graphic Abstract

scholarly journals Process Water Recirculation During Hydrothermal Carbonization as a Promising Process Step Towards the Production of N-doped Carbonaceous Materials

2021 ◽  
Author(s):  
Dominik Wüst ◽  
Pablo Arauzo ◽  
Sonja Habicht ◽  
Fernando Cazana ◽  
Luca Fiori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hydrothermal Carbonization ◽  
Added Value ◽  
Process Water ◽  
Chemical Characteristics ◽  
Carbonaceous Materials ◽  
Process Step ◽  
Physico Chemical ◽  
Liquid Products ◽  
Water Recirculation

Abstract Hydrothermal Carbonization (HTC) refers to the conversion of biogenic wastes into char-like solids with promising perspectives for application, but a process water (PW) results which is difficult to dispose untreated. Thus, a biorefinery approach including one or two recirculation steps with the additional objective of improving the physico-chemical characteristics of the solid was performed. During HTC, constitutive biomass molecules decompose into hundreds of organic compounds, following complex reactions. To get deeper insights a combination of proximate, ultimate and structural analysis for solid products as well as liquid chromatography for liquid products were the choice. The main reactions could be identified by key compounds of low and high molecular weight resulting from hydrolysis, dehydration, decarboxylation, deamination as well as amide formation and condensation reactions. Their intensity was influenced by the feedwater pH and reaction temperature. Reactions of Maillard character result in N-containing heterocycles incorporated into the hydrochar (HC), which promises the fabrication of high added-value materials, i.e. N-doped carbonaceous materials.

scholarly journals Sewage Sludge Treatment by Hydrothermal Carbonization: Feasibility Study for Sustainable Nutrient Recovery and Fuel Production

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2697
Author(s):  
Gabriel Gerner ◽  
Luca Meyer ◽  
Rahel Wanner ◽  
Thomas Keller ◽  
Rolf Krebs
Keyword(s):  
Liquid Phase ◽  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Economic Feasibility ◽  
Phosphorus Recovery ◽  
High Yield ◽  
Nutrient Recovery ◽  
Waste Biomass ◽  
Sludge Treatment ◽  
Sewage Sludge Treatment

Phosphorus recovery from waste biomass is becoming increasingly important, given that phosphorus is an exhaustible non-renewable resource. For the recovery of plant nutrients and production of climate-neutral fuel from wet waste streams, hydrothermal carbonization (HTC) has been suggested as a promising technology. In this study, digested sewage sludge (DSS) was used as waste material for phosphorus and nitrogen recovery. HTC was conducted at 200 °C for 4 h, followed by phosphorus stripping (PS) or leaching (PL) at room temperature. The results showed that for PS and PL around 84% and 71% of phosphorus, as well as 53% and 54% of nitrogen, respectively, could be recovered in the liquid phase (process water and/or extract). Heavy metals were mainly transferred to the hydrochar and only <1 ppm of Cd and 21–43 ppm of Zn were found to be in the liquid phase of the acid treatments. According to the economic feasibility calculation, the HTC-treatment per dry ton DSS with an industrial-scale plant would cost around 608 USD. Between 349–406 kg of sulfuric acid are required per dry ton DSS to achieve a high yield in phosphorus recovery, which causes additional costs of 96–118 USD. Compared to current sewage sludge treatment costs in Switzerland, which range between 669 USD and 1173 USD, HTC can be an economically feasible process for DSS treatment and nutrient recovery.

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