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Woody biowaste is a component which is difficult to be converted among multiple solid waste (MSW) during the hydrothermal carbonization (HTC). In this paper, poplar sawdust was pretreated by HTC to study the correlation between microstructure and gasification characteristics. The results showed the fixed carbon and higher calorific value increased from 13.44 % and 19.41 MJ/kg to 41.47 % and 25.85 MJ/kg after HTC, respectively. The cold gas efficiency of hydrochars prepared at 220 °C was the highest of 93.57 % compared with that of raw material of 76.65 %. It was found that carbon structure had a greater influence on hydrochars gasification characteristics than pore structure. The crystallinity of hydrochars had a good correlation with the total yield and H 2 /CO of syngas, which can provide guidance for HTC pretreatment of woody biowaste and MSW., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

[Display omitted] • (Co–)gasification assisted by CO 2 or steam was studied for CR, RH, SB and FR. • Multi-faceted synergistic indices based on various parameters were introduced. • FR showed the best performance in terms of weight loss and syngas generation. • Synergistic indices of FR + CR were 4–12 times higher than those of RH + CR and SB + CR. • Water-washing pretreatment of FR proved the positive role of acidic properties. Gasification technology is an effective way to achieve efficient, safe, and resourceful disposal of organic solid wastes (OSWs). Due to the complex sources and variable components of the OSWs, the co-disposal is highly essential. Various typical OSWs, including food waste (cooked rice, CR), agricultural waste (rice husk, RH; sugarcane bagasse, SB), and industrial waste (furfural residue, FR), were selected for this study. The gasification characteristics and synergistic performance were examined in terms of thermal weight loss characteristics under the CO 2 atmosphere and gaseous product characteristics under the steam atmosphere. The synergistic indices of performance parameters were introduced to quantify the synergistic effects. The gasification activity of FR was remarkably higher than that of other OSWs. In the co-gasification with CR under the CO 2 atmosphere, FR played an excellent positive synergistic effect, but the agricultural wastes played a slight or no synergistic effect. In the steam co-gasification, RH, SB, and FR all promoted the generation of syngas, in which FR showed still significant synergistic effects, with the synergistic indices of H 2 yield, syngas yield, CCE, and CGE being 4–12 times higher than those of other blended wastes. The excellent performance of FR in (co–)gasification was mainly attributed to the acidic properties of FR, which was confirmed by comparing the (co–)gasification performance of FR with and without water-washing pretreatment. The work provides guidance for the co-disposal of OSWs in industrial applications. [ABSTRACT FROM AUTHOR]

• Two schemes for collaborative disposal of food waste and yard waste were proposed. • H 2 -rich syngas could be obtained by co-gasification of poplar and hydrochar. • CO-rich syngas could be obtained by gasification of co-HTC hydrochar. • HTC was a pretreatment to regulate the composition and structure of raw materials. Kitchen waste and yard waste are typical components of municipal solid waste. In this paper, two schemes for collaborative disposal of these two wastes by hydrothermal carbonization (HTC) coupled with gasification were proposed and compared: Scheme 1: co-gasification of poplar with hydrochar derived from food waste; Scheme 2: direct gasification of hydrochar derived from co-HTC process of food waste and poplar. HTC was the pretreatment to regulate the composition and structure of raw materials. After HTC, the H/C and O/C of food waste decreased to the minimum of 1.06 and 0.14, respectively, and the coalification degree was increased close to lignite. Most of K and Na would be removed but Ca was enriched during HTC process, in which hydrochar derived from food waste at 260 °C contained the highest Ca content of 3752.30 mg/kg. The C=C and C=O functional groups of hydrochar were richer than the raw materials indicating the aromatization degree was improved. In Scheme 1, the gasification feedstock had relatively higher alkali and alkaline earth metals and volatile, resulting in a rapid gasification and the H 2 /CO ratio was between 1.6 and 1.8. In Scheme 2, the co-HTC hydrochar had high content of fixed carbon which can reach the maximum of 48.62 wt.% when the temperature was 260 °C. Due to the richer surface functional group structure, especially C=O, the hydrochar was easy to crack into CO during the initial gasification stage, and H 2 /CO ratios of the syngas were all less than 1. HTC coupled with gasification could broad the waste usage to meet the different industrial process needs, which can achieve waste disposal and energy conversion efficiently. [ABSTRACT FROM AUTHOR]