Study on impact mechanism of iron-modified biochar addition on dewatering performance of food waste digestate

ZHU Jing; YANG Xue; TAO Hong; ZHANG Wei

doi:10.13205/j.hjgc.202505014

Volume 43 Issue 5

May 2025

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Article Navigation > ENVIRONMENTAL ENGINEERING > 2025 > 43(5): 124-133

ZHU Jing, YANG Xue, TAO Hong, ZHANG Wei. Study on impact mechanism of iron-modified biochar addition on dewatering performance of food waste digestate[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(5): 124-133. doi: 10.13205/j.hjgc.202505014

Citation:

ZHU Jing, YANG Xue, TAO Hong, ZHANG Wei. Study on impact mechanism of iron-modified biochar addition on dewatering performance of food waste digestate[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(5): 124-133. doi: 10.13205/j.hjgc.202505014

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Study on impact mechanism of iron-modified biochar addition on dewatering performance of food waste digestate

doi: 10.13205/j.hjgc.202505014

School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China

Received Date: 2023-10-12
Accepted Date: 2024-03-08
Rev Recd Date: 2023-12-22

Available Online: 2025-09-11

Abstract

Abstract

The high moisture content of biogas residue and the difficulty in subsequent dewatering treatment are both the bottleneck issues affecting the anaerobic digestion of food waste and the resource utilization of biogas residue. This study investigated the changing trend in dewaterability of biogas residue during the anaerobic digestion of food waste with iron-modified biochar （Fe-BC） addition， and clarified the mechanism by which iron-modified biochar improved the dewaterability. The results showed that， compared to the control group， the methane accumulation production of the Fe-BC group increased by 263.6% on the 30th day， while the normalized capillary water absorption time （NCST） decreased by 45.9%. The highest volatile suspended solids degradation rate reached 36.7% in the Fe-BC group after anaerobic digestion. The adsorption capacity of biochar alleviated ammonia inhibition， and its larger specific surface area facilitated microbial attachment and growth. As a conductive material， Fe-BC facilitated the formation of microbial aggregates associated with electron transfer， thereby establishing an electron transfer network that promoted the growth of co-metabolizing methanogens. Methane bacteria hydrolyzed large organic molecules to induce effective decomposition of EPS. Compared with the initial acidification stage of anaerobic digestion， the protein content in extracellular polymeric substances （EPS） during the stable stage decreased by 72.89%， while the carboxyl and carbonyl groups on the surface of EPS decreased by 11.2% and 13.7%， respectively. The structure of EPS was disrupted， promoting the conversion of bound water to free water. The porous structure of biochar provided a large specific surface area， offering sites for microbial attachment and growth， increasing biomass， improving protein and polysaccharide degradation， weakening the water holding capacity of EPS significantly， and enhancing dehydration performance. Moreover， the addition of Fe-BC rapidly increased the abundance of Metanoculleus， destoryed this polymer structure， convered bound water into free water， and promoted the degradation of organic compounds in EPS； during the anaerobic digestion and methanation stage， oxygen acyl reductase （OR） and acetyllactate synthetase （AS） was consumed by 33.4% and 43.6%， respectively， promoting the decomposition of volatile fatty acids （VFAs）， thereby disrupting the binding effect between organic matter and water， resulting in a decrease in bound water content and improvement of biogas residue dewaterability. This research can provide a reference for the mechanism of Fe-BC in the dehydration of food waste biogas residue.
- food waste biogas residue,
- iron-modified biochar,
- dewaterability,
- microbial community,
- enzyme

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References(24)

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