Absorbing oxygen carriers promotes phosphorus recovery from sludge via the microwave thermal conversion process

• Published in: Bioresource technology 2024-06, Vol.401, p.130760-130760, Article 130760
• Main Authors: Yan, Xiaoyu, Zhao, Shuheng, Hu, Jianjun, Dang, Jiatao, Yao, Sen, Cai, Junmeng, Sittijunda, Sureewan, Wang, Wei, Lee, Duu-Jong, Yang, Panbo
• Format: Article
• Language: English
• Subjects: Absorbing oxygen carrier; Phosphorus forms; Phosphorus migration and transformation; Sludge; Sludge char
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2024.130760

[Display omitted] •Increased the specific surface area of char and facilitate H2 production.•The non-apatite inorganic phosphorus content in char increased.•Pyrophosphate is generated at the low-temperature reaction stage.•Compositions with alkali metals and phosphorus are stable.•Low-temperature catalytic reaction and high-temperature gasification are noted. This study aims to apply the Absorbing oxygen carriers (AOCs) to induce the migration and transformation of phosphorus compounds during the microwave thermal conversion of sludge so the hard-to-extract organic phosphorus (OP) can be converted to easy-to-extract inorganic phosphorus (IP) and be enriched onto the sludge char. The AOCs were recycled by screen separation from the IP-rich sludge char, with the latter being a renewable phosphorus source from sludge. The AOCs in this novel process enhanced the conversion efficiency of OP into non-apatite inorganic phosphorus (NAlP), which was further converted to apatite inorganic phosphorus (AP). Most phosphorus in the sludge char is presented in the form of orthophosphate.