Influence of water content and organic matter on the mechanical strength characteristics of municipal sewage sludge
- 1School of Architecture, Anhui Science and Technology University, Bengbu, Anhui Province, China.
- 2Green Materials R&D Lab, Bengbu Architectural Design And Research Institute Group Co. Ltd, Bengbu, Anhui Province, China.
Abstract
Municipal sewage sludge typically has high moisture and organic matter contents, which exert a significant influence on mechanical strength, dewatering and resource recovery. Organic soil specimens with varying water contents were prepared by mixing raw sewage sludge (RSS) with dry soil powder (DSP), humus, and quartz sand tailings (QST). Unconfined compressive strength (UCS) tests were conducted to investigate the effect of water content on the UCS. Results show that the UCS decreases with normalized water content (w₀/wL) following a power-law relationship, and a quantitative formula is established. Specimens with different organic contents were fabricated by blending DSP into RSS. Unconsolidated undrained triaxial tests were performed to assess strength evolution with organic content. For organic high-liquid-limit silt, the angle of internal friction changes slightly with organic content (wu), maintaining a low value of 1–3°. Cohesion decreases gradually when wu < 17%, drops sharply when 17% < wu < 21%, and stabilizes at around 6 kPa when wu > 21%. An organic content of 17–21% serves as a possible transition interval for sludge structure and strength degradation. Mechanism analysis reveals that the contribution of organic matter to soil strength is predominantly governed by cementation, with negligible influence on the internal friction angle. The reduction in cohesion is primarily attributed to the decrease in dry unit weight, degradation of mineral skeleton, a predominance of the soft organic matrix, and increased plastic deformation.
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BibTeX
@article{yang2026influence,
title = {{Influence of water content and organic matter on the mechanical strength characteristics of municipal sewage sludge}},
author = {Ruimin Yang and Jiadong Ma and Zhenning Zhang and Jing Yin},
journal = {PLOS One},
year = {2026},
month = oct,
doi = {10.1371/journal.pone.0359715},
url = {https://doi.org/10.1371/journal.pone.0359715},
note = {CC BY},
}
RIS
TY - JOUR
TI - Influence of water content and organic matter on the mechanical strength characteristics of municipal sewage sludge
AU - Ruimin Yang
AU - Jiadong Ma
AU - Zhenning Zhang
AU - Jing Yin
PY - 2026
DA - 2026/10/29
JO - PLOS One
DO - 10.1371/journal.pone.0359715
UR - https://doi.org/10.1371/journal.pone.0359715
AB - Municipal sewage sludge typically has high moisture and organic matter contents, which exert a significant influence on mechanical strength, dewatering and resource recovery. Organic soil specimens with varying water contents were prepared by mixing raw sewage sludge (RSS) with dry soil powder (DSP), humus, and quartz sand tailings (QST). Unconfined compressive strength (UCS) tests were conducted to investigate the effect of water content on the UCS. Results show that the UCS decreases with normalized water content (w₀/wL) following a power-law relationship, and a quantitative formula is established. Specimens with different organic contents were fabricated by blending DSP into RSS. Unconsolidated undrained triaxial tests were performed to assess strength evolution with organic content. For organic high-liquid-limit silt, the angle of internal friction changes slightly with organic content (wu), maintaining a low value of 1–3°. Cohesion decreases gradually when wu < 17%, drops sharply when 17% < wu < 21%, and stabilizes at around 6 kPa when wu > 21%. An organic content of 17–21% serves as a possible transition interval for sludge structure and strength degradation. Mechanism analysis reveals that the contribution of organic matter to soil strength is predominantly governed by cementation, with negligible influence on the internal friction angle. The reduction in cohesion is primarily attributed to the decrease in dry unit weight, degradation of mineral skeleton, a predominance of the soft organic matrix, and increased plastic deformation.
SN - 1932-6203
ER -