The formation of humic-like acids(HLAs)is an essential process for converting liquid digestate into organic soil amendments to enhance agricultural sustainability.The aim of this study was to investigate the impact of oxygen and/or MnO2 on the production of HLAs.Herein,abiotic humification performance of the digestate dissolved organic matter(DOM)is investigated with fluxes of air and N2 in the absence and presence of MnO2.Our results demonstrated that the fate of digestate DOM greatly depends on the oxidizing environment,the MnO2 enhanced nitrogen involved in the formation of HLAs.The synergistic effects of MnO2 and oxygen effectively improved the production of HLAs,and the corresponding component evolution was analyzed using spectroscopic evidence.The two-dimensional correlation spectroscopy results demonstrated that the reaction sequence of digestate DOM followed the order of protein-like substances,substances with an absorbance at 325 nm,substances with UV absorbance at 254 nm and HLAs.Additionally,excitation emission matrix fluorescence combined with parallel factor analysis(EEM-PARAFAC)showed that tryptophan-like C3 was more prone to transformation than tyrosine-like C2 and was responsible for the humification process.The substance with an absorbance at 325 nm was a reaction intermediate in the transformation process of protein-like substances to HLAs.The above findings can be used to promote the production of liquid fertilizer associated with carbon sequestration as well as the sustainable development of biogas production.

Yingchao Zhang;Hongqiong Zhang;Xinwei Dong;Dongbei Yue;Ling Zhou

Heibei Key Laboratory of Heavy Metal Deep-Remediation in Water and Resource Reuse,Key Laboratory of Applied Chemistry,School of Environmental and Chemical Engineering,Yanshan University,Qinhuangdao 066004,China;School of Environment,Tsinghua University,Beijing 100084,China;College of Engineering,Northeast Agricultural University,Harbin 150030,China;School of Mechanical Electrification Engineering,Tarim University,Alaer 843300,China

环境科学与工程前沿

[1]Yingchao Zhang;Hongqiong Zhang;Xinwei Dong;Dongbei Yue;Ling Zhou-.Effects of oxidizing environment on digestate humification and identification of substances governing the dissolved organic matter(DOM)transformation process)[J].环境科学与工程前沿,2022(08):24-36

digestate,HLAs

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