Impact of biochar on anaerobic digestion of sewage sludge and environmental risks of heavy metals

LIU Qinghong; QIU Chunsheng; LIU Nannan; LIU Bo; MA Junli; CHEN Xu; ZHANG Yaping; WANG Shaopo

doi:10.13205/j.hjgc.202506003

Volume 43 Issue 6

Jun. 2025

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Article Navigation > ENVIRONMENTAL ENGINEERING > 2025 > 43(6): 24-33

LIU Qinghong, QIU Chunsheng, LIU Nannan, LIU Bo, MA Junli, CHEN Xu, ZHANG Yaping, WANG Shaopo. Impact of biochar on anaerobic digestion of sewage sludge and environmental risks of heavy metals[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(6): 24-33. doi: 10.13205/j.hjgc.202506003

Citation:

LIU Qinghong, QIU Chunsheng, LIU Nannan, LIU Bo, MA Junli, CHEN Xu, ZHANG Yaping, WANG Shaopo. Impact of biochar on anaerobic digestion of sewage sludge and environmental risks of heavy metals[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(6): 24-33. doi: 10.13205/j.hjgc.202506003

Citation:

LIU Qinghong, QIU Chunsheng, LIU Nannan, LIU Bo, MA Junli, CHEN Xu, ZHANG Yaping, WANG Shaopo. Impact of biochar on anaerobic digestion of sewage sludge and environmental risks of heavy metals[J]. ENVIRONMENTAL ENGINEERING , 2025, 43(6): 24-33. doi: 10.13205/j.hjgc.202506003

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Impact of biochar on anaerobic digestion of sewage sludge and environmental risks of heavy metals

doi: 10.13205/j.hjgc.202506003

1. Tianjin Key Laboratory of Aquatic Science and Technology, School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin 300384, China;
2. College of Ecology and Environment, Hainan Tropical Ocean University, Sanya 572022, China

Received Date: 2024-10-21
Accepted Date: 2024-12-28
Rev Recd Date: 2024-12-03

Abstract

Abstract

Biochar can effectively improve sludge digestion efficiency and stabilize heavy metals. In this study， biochar was prepared from poplar sawdust under anoxic conditions at 300℃， 500℃ and 700℃， respectively， and the effects of biochar addition on municipal sludge anaerobic digestion efficiency，as well as the contents， chemical speciation， and ecological risks of heavy metals（Cu， As， Ni， Cr and Pb）were investigated. The results showed that biochar addition could contribute to maintaining the stability of pH level and alleviating ammonia nitrogen accumulation in the anaerobic digestion system， and the cumulative methane production increased by 80.55% to 132.52% compared to the control group. Biochar prepared at 700℃ with a dosage of 20 g/L was better than other preparing conditions in promoting anaerobic digestion efficiency. After biochar addition， the content of heavy metals in anaerobically digested sludge increased by 4.79% to 85.54% compared to the control group， both the single-factor pollution index （PI _i ） and the Nemerow pollution index （NPI） of heavy metals in the digested sludge increased in varying degrees， but the PI _i and NPI values were still less than 1 （indicating a clean level）. In addition， the proportion of heavy metals existed in acid-soluble/exchangeable fraction decreased， while the residual fraction increased in the anaerobically digested sludge with biochar addition. The risk index（RI） value of heavy metals was 58 at a biochar （500 ℃） dosage of 20 g/L， which was 47.75% lower than that of the control group. The potential ecological risks of heavy metals in anaerobically digested sludge could be effectively controlled by biochar addition.
- sludge,
- anaerobic digestion,
- biochar,
- heavy metals,
- ecological risk,
- chemical speciation

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References(51)

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