{"id":1477,"date":"2026-03-03T10:57:27","date_gmt":"2026-03-03T09:57:27","guid":{"rendered":"https:\/\/sites.unica.it\/hydrochar\/?page_id=1477"},"modified":"2026-03-27T12:08:51","modified_gmt":"2026-03-27T11:08:51","slug":"co-hydrothermal-carbonization-co-htc","status":"publish","type":"page","link":"https:\/\/sites.unica.it\/hydrochar\/wikichar\/hydrothermal-processes-htp\/hydrothermal-carbonization-htc\/co-hydrothermal-carbonization-co-htc\/","title":{"rendered":"Co-Hydrothermal Carbonization (Co-HTC)"},"content":{"rendered":"\n<p><em>Exploring co-hydrothermal carbonization (Co-HTC) for enhancing process efficiency and product quality from mixed feedstocks<\/em><\/p>\n\n\n\n<hr class=\"wp-block-separator aligncenter has-alpha-channel-opacity is-style-wide\" \/>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-28f84493 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h2 class=\"wp-block-heading\">Introduction<\/h2>\n\n\n\n<p>Co\u2011HTC is a thermochemical process that involves the simultaneous carbonization of two or more types of biomass or organic wastes under elevated temperature and pressure in the presence of water (typically 180\u2013250\u202f\u00b0C, saturated pressure, several hours) offering synergistic effects that can enhance the quality of both the hydrochar and process water, mainly fuel quality, yield, dechlorination\/desulfurization, nutrient transformation, overall resource recovery, and environmental performance (<a href=\"https:\/\/doi.org\/10.1016\/j.jclepro.2021.126734\" target=\"_blank\" rel=\"noreferrer noopener\">Bardhan et al., 2021<\/a>; <a href=\"https:\/\/doi.org\/10.1016\/j.cogsc.2025.101024\" target=\"_blank\" rel=\"noreferrer noopener\">Shanmugam et al., 2025<\/a>; <a href=\"https:\/\/doi.org\/10.1016\/j.scitotenv.2022.158034\" target=\"_blank\" rel=\"noreferrer noopener\">Wang et al., 2022<\/a>; <a href=\"https:\/\/doi.org\/10.1016\/j.jenvman.2017.06.018\" target=\"_blank\" rel=\"noreferrer noopener\">Zhang et al., 2017<\/a>).<\/p>\n\n\n\n<p>Typical feedstock combination:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>biomass and fossil-based feedstock (<a href=\"https:\/\/doi.org\/10.1016\/j.cej.2022.141004\" target=\"_blank\" rel=\"noreferrer noopener\">Fakudze &amp; Chen, 2023<\/a>)<\/li>\n\n\n\n<li>sewage sludge and lignocellulosic biomass, e.g., pine sawdust, bagasse, sunflower straw, etc. (<a href=\"https:\/\/doi.org\/10.1016\/j.energy.2021.119896\" target=\"_blank\" rel=\"noreferrer noopener\">Lu et al., 2021<\/a>; <a href=\"https:\/\/doi.org\/10.1016\/j.renene.2021.06.101\" target=\"_blank\" rel=\"noreferrer noopener\">Wilk et al., 2021<\/a>)<\/li>\n\n\n\n<li>sewage sludge and food waste (<a href=\"https:\/\/doi.org\/10.1016\/j.biortech.2019.121347\" target=\"_blank\" rel=\"noreferrer noopener\">Zheng et al., 2019<\/a>)<\/li>\n\n\n\n<li>manure and municipal organic waste (<a href=\"https:\/\/doi.org\/10.1016\/j.renene.2024.120916\" target=\"_blank\" rel=\"noreferrer noopener\">Rosas-Mendoza et al., 2024<\/a>)<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"724\" height=\"1024\" src=\"http:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-724x1024.png\" alt=\"\" class=\"wp-image-1479\" srcset=\"https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-724x1024.png 724w, https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-212x300.png 212w, https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-768x1086.png 768w, https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-1086x1536.png 1086w, https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1-1448x2048.png 1448w, https:\/\/sites.unica.it\/hydrochar\/files\/2026\/03\/Co-HTC-scheme1.png 1750w\" sizes=\"auto, (max-width: 724px) 100vw, 724px\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Theory and Mechanisms<\/strong><\/h2>\n\n\n\n<p>The underlying HTC mechanisms remain the same, but interactions between feedstocks introduce synergistic effects that can enhance product properties. The main chemical mechanisms includes hydrolysis, dehydration, decarboxylation, condensation and polymerization, aromatization, recondensation which occur in a complex, parallel, and sometimes sequential network, with the specific pathways and product distributions.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong><strong>Key Parameters<\/strong><\/strong><\/h2>\n\n\n\n<p>The most significant factors are the feedstock composition, feedstock mixing ratio, reaction temperature, pressure, and residence time.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Synergistic effects<\/strong><\/h2>\n\n\n\n<p>Co\u2011HTC often produces hydrochar with higher yield, carbon retention, and heating value than expected from individual feedstocks, showing clear positive synergy (<a href=\"https:\/\/doi.org\/10.1016\/j.jaap.2024.106777\" target=\"_blank\" rel=\"noreferrer noopener\">Cui et al., 2024<\/a>). Key mechanisms include Maillard and Mannich reactions that enhance aromatization and N\u2011heterocycle formation in mixed biomass systems (<a href=\"https:\/\/doi.org\/10.1016\/j.energy.2024.131028\" target=\"_blank\" rel=\"noreferrer noopener\">Shen et al., 2024<\/a>). Complementary chemistry, such as minerals or organic acids, promotes desulfurization and dichlorination when biomass is combined with coal (<a href=\"https:\/\/doi.org\/10.1016\/j.jece.2022.107519\" target=\"_blank\" rel=\"noreferrer noopener\">Fakudze et al., 2022<\/a>). Synergy also improves combustion performance in sludge\u2011 and manure\u2011based blends (<a href=\"https:\/\/doi.org\/10.1016\/j.renene.2024.120547\" target=\"_blank\" rel=\"noreferrer noopener\">Wilk et al., 2024<\/a>; <a href=\"https:\/\/doi.org\/10.1016\/j.fuproc.2025.108345\" target=\"_blank\" rel=\"noreferrer noopener\">Huang et al., 2025<\/a>). However, antagonistic effects can occur in mixtures with incompatible reaction pathways, such as certain biomass\u2013fossil combinations (<a href=\"https:\/\/doi.org\/10.1016\/j.cej.2022.141004\" target=\"_blank\" rel=\"noreferrer noopener\">Fakudze &amp; Chen, 2023<\/a>).<\/p>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\ud83d\udcd6 References<\/h2>\n\n\n\n<p>Bardhan, M., Novera, T.M., Tabassum, M., Islam, Md. Azharul, Islam, Md. Atikul, Hameed, B.H., 2021. Co-hydrothermal carbonization of different feedstocks to hydrochar as potential energy for the future world: A review. J. Clean. Prod. 298, 126734. <a href=\"https:\/\/doi.org\/10.1016\/j.jclepro.2021.126734\">https:\/\/doi.org\/10.1016\/j.jclepro.2021.126734<\/a><\/p>\n\n\n\n<p>Cui, D., Zhang, B., Liu, Y., Wu, S., Wang, X., Wang, Q., Zhang, X., Fattahi, M., Zhang, J., 2024. Hydrochar from co-hydrothermal carbonization of sewage sludge and sunflower stover: Synergistic effects and combustion characteristics. J. Anal. Appl. Pyrolysis 183, 106777. <a href=\"https:\/\/doi.org\/10.1016\/j.jaap.2024.106777\">https:\/\/doi.org\/10.1016\/j.jaap.2024.106777<\/a><\/p>\n\n\n\n<p>Fakudze, S., Chen, J., 2023. A critical review on co-hydrothermal carbonization of biomass and fossil-based feedstocks for cleaner solid fuel production: Synergistic effects and environmental benefits. Chemical Engineering Journal 457, 141004. <a href=\"https:\/\/doi.org\/10.1016\/j.cej.2022.141004\">https:\/\/doi.org\/10.1016\/j.cej.2022.141004<\/a><\/p>\n\n\n\n<p>Fakudze, S., Wei, Y., Zhou, P., Han, J., Chen, J., 2022. Synergistic effects of process-generated organic acids during co-hydrothermal carbonization of watermelon peel and high-sulfur coal. J. Environ. Chem. Eng. 10, 107519. <a href=\"https:\/\/doi.org\/10.1016\/j.jece.2022.107519\">https:\/\/doi.org\/10.1016\/j.jece.2022.107519<\/a><\/p>\n\n\n\n<p>Huang, K., Zhang, X., Li, X., Liu, R., Wu, K., 2025. Exploration on physicochemical properties and combustion behaviors of hydrochar from co-hydrothermal carbonization of swine manure and tea waste. Fuel Processing Technology 278, 108345. <a href=\"https:\/\/doi.org\/10.1016\/j.fuproc.2025.108345\">https:\/\/doi.org\/10.1016\/j.fuproc.2025.108345<\/a><\/p>\n\n\n\n<p>Lu, X., Ma, X., Chen, X., 2021. Co-hydrothermal carbonization of sewage sludge and lignocellulosic biomass: Fuel properties and heavy metal transformation behaviour of hydrochars. Energy 221, 119896. <a href=\"https:\/\/doi.org\/10.1016\/j.energy.2021.119896\">https:\/\/doi.org\/10.1016\/j.energy.2021.119896<\/a><\/p>\n\n\n\n<p>Rosas-Mendoza, E.S., Alvarado-Vallejo, A., Vallejo-Cant\u00fa, N.A., Velasco-Santos, C., Alvarado-Lassman, A., 2024. Valorization of the complex organic waste in municipal solid wastes through the combination of hydrothermal carbonization and anaerobic digestion. Renew. Energy 231, 120916. <a href=\"https:\/\/doi.org\/10.1016\/j.renene.2024.120916\">https:\/\/doi.org\/10.1016\/j.renene.2024.120916<\/a><\/p>\n\n\n\n<p>Shanmugam, V., Kaynak, E., Das, O., Padhye, L.P., 2025. The effects of feedstock types and their properties on hydrothermal carbonisation and resulting hydrochar: A review. Curr. Opin. Green Sustain. Chem. 53, 101024. <a href=\"https:\/\/doi.org\/10.1016\/j.cogsc.2025.101024\">https:\/\/doi.org\/10.1016\/j.cogsc.2025.101024<\/a><\/p>\n\n\n\n<p>Shen, Q., Zhu, Xianqing, Peng, Y., Xu, M., Huang, Y., Xia, A., Zhu, Xun, Liao, Q., 2024. Structure evolution characteristic of hydrochar and nitrogen transformation mechanism during co-hydrothermal carbonization process of microalgae and biomass. Energy 295, 131028. <a href=\"https:\/\/doi.org\/10.1016\/j.energy.2024.131028\">https:\/\/doi.org\/10.1016\/j.energy.2024.131028<\/a><\/p>\n\n\n\n<p>Wang, Q., Wu, S., Cui, D., Zhou, H., Wu, D., Pan, S., Xu, F., Wang, Z., 2022. Co-hydrothermal carbonization of organic solid wastes to hydrochar as potential fuel: A review. Science of The Total Environment 850, 158034. <a href=\"https:\/\/doi.org\/10.1016\/j.scitotenv.2022.158034\">https:\/\/doi.org\/10.1016\/j.scitotenv.2022.158034<\/a><\/p>\n\n\n\n<p>Wilk, M., \u015aliz, M., Czerwi\u0144ska, K., Gajek, M., Kalemba-Rec, I., 2024. Improvements in dewaterability and fuel properties of hydrochars derived from hydrothermal co-carbonization of sewage sludge and organic waste. Renew. Energy 227, 120547. <a href=\"https:\/\/doi.org\/10.1016\/j.renene.2024.120547\">https:\/\/doi.org\/10.1016\/j.renene.2024.120547<\/a><\/p>\n\n\n\n<p>Wilk, M., \u015aliz, M., Lubieniecki, B., 2021. Hydrothermal co-carbonization of sewage sludge and fuel additives: Combustion performance of hydrochar. Renew. Energy 178, 1046\u20131056. <a href=\"https:\/\/doi.org\/10.1016\/j.renene.2021.06.101\">https:\/\/doi.org\/10.1016\/j.renene.2021.06.101<\/a><\/p>\n\n\n\n<p>Zhang, X., Zhang, L., Li, A., 2017. Hydrothermal co-carbonization of sewage sludge and pinewood sawdust for nutrient-rich hydrochar production: Synergistic effects and products characterization. J. Environ. Manage. 201, 52\u201362. <a href=\"https:\/\/doi.org\/10.1016\/j.jenvman.2017.06.018\">https:\/\/doi.org\/10.1016\/j.jenvman.2017.06.018<\/a><\/p>\n\n\n\n<p>Zheng, C., Ma, X., Yao, Z., Chen, X., 2019. The properties and combustion behaviors of hydrochars derived from co-hydrothermal carbonization of sewage sludge and food waste. Bioresour. Technol. 285, 121347. <a href=\"https:\/\/doi.org\/10.1016\/j.biortech.2019.121347\">https:\/\/doi.org\/10.1016\/j.biortech.2019.121347<\/a><\/p>\n\n\n\n<div class=\"wp-block-group alignfull has-contrast-color has-text-color is-vertical is-content-justification-center is-layout-flex wp-container-core-group-is-layout-84c28ab9 wp-block-group-is-layout-flex\" style=\"min-height:40vh;margin-top:0;margin-bottom:0;padding-top:var(--wp--preset--spacing--60);padding-right:var(--wp--preset--spacing--50);padding-bottom:var(--wp--preset--spacing--60);padding-left:var(--wp--preset--spacing--50)\"><div style=\"margin-bottom:6px;\" class=\"aligncenter wp-block-site-logo\"><a href=\"https:\/\/sites.unica.it\/hydrochar\/\" class=\"custom-logo-link\" rel=\"home\"><img loading=\"lazy\" decoding=\"async\" width=\"272\" height=\"103\" src=\"https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-scaled.png\" class=\"custom-logo\" alt=\"Hydrochar Network\" srcset=\"https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-scaled.png 2560w, https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-300x114.png 300w, https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-1024x389.png 1024w, https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-768x292.png 768w, https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-1536x583.png 1536w, https:\/\/sites.unica.it\/hydrochar\/files\/2025\/11\/logoTEXT_new-2048x777.png 2048w\" sizes=\"auto, (max-width: 272px) 100vw, 272px\" \/><\/a><\/div>\n\n\n<p class=\"has-text-align-center has-medium-font-size\">Follow us:<\/p>\n\n\n\n<ul class=\"wp-block-social-links has-normal-icon-size is-style-logos-only is-nowrap is-layout-flex wp-container-core-social-links-is-layout-65900438 wp-block-social-links-is-layout-flex\"><li class=\"wp-social-link wp-social-link-linkedin  wp-block-social-link\"><a href=\"https:\/\/linkedin.com\/company\/hydrochar-network\" class=\"wp-block-social-link-anchor\"><svg width=\"24\" height=\"24\" viewBox=\"0 0 24 24\" version=\"1.1\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" aria-hidden=\"true\" focusable=\"false\"><path d=\"M19.7,3H4.3C3.582,3,3,3.582,3,4.3v15.4C3,20.418,3.582,21,4.3,21h15.4c0.718,0,1.3-0.582,1.3-1.3V4.3 C21,3.582,20.418,3,19.7,3z M8.339,18.338H5.667v-8.59h2.672V18.338z M7.004,8.574c-0.857,0-1.549-0.694-1.549-1.548 c0-0.855,0.691-1.548,1.549-1.548c0.854,0,1.547,0.694,1.547,1.548C8.551,7.881,7.858,8.574,7.004,8.574z M18.339,18.338h-2.669 v-4.177c0-0.996-0.017-2.278-1.387-2.278c-1.389,0-1.601,1.086-1.601,2.206v4.249h-2.667v-8.59h2.559v1.174h0.037 c0.356-0.675,1.227-1.387,2.526-1.387c2.703,0,3.203,1.779,3.203,4.092V18.338z\"><\/path><\/svg><span class=\"wp-block-social-link-label screen-reader-text\">LinkedIn<\/span><\/a><\/li><\/ul>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Exploring co-hydrothermal carbonization (Co-HTC) for enhancing process efficiency and product quality from mixed feedstocks Introduction Co\u2011HTC is a thermochemical process that involves the simultaneous carbonization of two or more types of biomass or organic wastes under [&hellip;]<\/p>\n","protected":false},"author":3514,"featured_media":0,"parent":118,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1477","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/pages\/1477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/users\/3514"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/comments?post=1477"}],"version-history":[{"count":7,"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/pages\/1477\/revisions"}],"predecessor-version":[{"id":1610,"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/pages\/1477\/revisions\/1610"}],"up":[{"embeddable":true,"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/pages\/118"}],"wp:attachment":[{"href":"https:\/\/sites.unica.it\/hydrochar\/wp-json\/wp\/v2\/media?parent=1477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}