Process water recirculation for catalytic hydrothermal carbonization of anaerobic digestate: Water-Energy-Nutrient Nexus

He, M., Cao, Y., Xu, Z., You, S. , Ruan, R., Gao, B., Wong, K.-H. and Tsang, D. C.W. (2022) Process water recirculation for catalytic hydrothermal carbonization of anaerobic digestate: Water-Energy-Nutrient Nexus. Bioresource Technology, 361, 127694. (doi: 10.1016/j.biortech.2022.127694)

Abstract

The process water (PW) from acid-catalyzed hydrothermal carbonization (HTC) is still an environmental burden due to the enriched organics, nutrients, and salts. This study proposed a novel strategy to valorize food waste digestate into multifunctional hydrochar by recirculating the PW in the HCl-catalyzed HTC process. The produced multifunctional hydrochar could be utilized as a high-quality solid fuel with HHV of 27.9 MJ kg-1 (hydrochar without PW recirculation) and a slow-release fertilizer by converting the complex Ca and P compounds from the food waste digestate into a Ca-P deposit (hydroxyapatite) with more than a 93% P recovery rate (hydrochar with PW recirculation). Adding fresh HCl in the HTC PW recirculation system only displayed a marginal catalytic impact on the hydrochar properties after two cycles of recirculation. This study demonstrated the importance of inherent Ca in the feedstocks and the dual role of HCl in the HTC with PW recirculation.

• Item Type: Articles
• Additional Information: The authors appreciate the financial support from the Hong Kong Environment and Conservation Fund (Project 101/2020).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: You, Dr Siming

Creator Roles

You, S.: Conceptualization, Writing – review and editing

• Authors: He, M., Cao, Y., Xu, Z., You, S., Ruan, R., Gao, B., Wong, K.-H., and Tsang, D. C.W.
• College/School: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Bioresource Technology
• Publisher: Elsevier
• ISSN: 0960-8524
• ISSN (Online): 1873-2976
• Published Online: 26 July 2022
• Copyright Holders: Copyright © 2022 Elsevier
• First Published: First published in Bioresource Technology 361: 127694
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher