Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment

Abstract Rapid infrastructure development generates large volumes of high-water-content sludge, creating an urgent need for efficient recycling and management strategies. This study introduces the flocculation–solidification–vacuum preloading (FSVP) method to enhance dewatering efficiency and streng...

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Main Authors: Lufan Li, Hongen Wu, Xukun Yang, Jianwen Wei, Yunliang Cui
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-025-96752-7
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author Lufan Li
Hongen Wu
Xukun Yang
Jianwen Wei
Yunliang Cui
author_facet Lufan Li
Hongen Wu
Xukun Yang
Jianwen Wei
Yunliang Cui
author_sort Lufan Li
collection DOAJ
description Abstract Rapid infrastructure development generates large volumes of high-water-content sludge, creating an urgent need for efficient recycling and management strategies. This study introduces the flocculation–solidification–vacuum preloading (FSVP) method to enhance dewatering efficiency and strength development, facilitating subsequent mechanical construction requirements. To enhance solidification and reduce cement consumption, the response surface method was used to determine the optimal composite curing agent, which consists of 53% cement, 32% rice husk ash, and 15% sodium silicate. Vacuum dewatering was applied to sludge samples treated with different flocculants and curing agents to assess their synergistic effects on soil improvement. The mixed flocculant of polyaluminum chloride and anionic polyacrylamide significantly increased the micropore content and compactness, with pore sizes primarily concentrated around 0.01 μm. While the flocculant facilitated efficient drainage, required unconfined compressive strength could only be achieved with the further addition of a curing agent. The optimal composite curing agent formulation induced hydration and pozzolanic reactions, filling larger pores with cementitious materials and enhancing soil strength. As a result, the vane shear strength reached 58 kPa and unconfined compressive strength reached 365 kPa at 7 days, further increasing to 586 kPa at 28 days.
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spelling doaj-art-c0c3e39e400c4d82a76c32f14b6fa0be2025-08-20T02:16:59ZengNature PortfolioScientific Reports2045-23222025-04-0115111710.1038/s41598-025-96752-7Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatmentLufan Li0Hongen Wu1Xukun Yang2Jianwen Wei3Yunliang Cui4School of Engineering, Hangzhou City UniversityPowerChina HuaDong Engineering Corporation LimitedSchool of Engineering, Hangzhou City UniversitySchool of Engineering, Hangzhou City UniversitySchool of Engineering, Hangzhou City UniversityAbstract Rapid infrastructure development generates large volumes of high-water-content sludge, creating an urgent need for efficient recycling and management strategies. This study introduces the flocculation–solidification–vacuum preloading (FSVP) method to enhance dewatering efficiency and strength development, facilitating subsequent mechanical construction requirements. To enhance solidification and reduce cement consumption, the response surface method was used to determine the optimal composite curing agent, which consists of 53% cement, 32% rice husk ash, and 15% sodium silicate. Vacuum dewatering was applied to sludge samples treated with different flocculants and curing agents to assess their synergistic effects on soil improvement. The mixed flocculant of polyaluminum chloride and anionic polyacrylamide significantly increased the micropore content and compactness, with pore sizes primarily concentrated around 0.01 μm. While the flocculant facilitated efficient drainage, required unconfined compressive strength could only be achieved with the further addition of a curing agent. The optimal composite curing agent formulation induced hydration and pozzolanic reactions, filling larger pores with cementitious materials and enhancing soil strength. As a result, the vane shear strength reached 58 kPa and unconfined compressive strength reached 365 kPa at 7 days, further increasing to 586 kPa at 28 days.https://doi.org/10.1038/s41598-025-96752-7SludgeFlocculationSolidificationVacuum preloadingRice husk ash
spellingShingle Lufan Li
Hongen Wu
Xukun Yang
Jianwen Wei
Yunliang Cui
Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
Scientific Reports
Sludge
Flocculation
Solidification
Vacuum preloading
Rice husk ash
title Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
title_full Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
title_fullStr Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
title_full_unstemmed Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
title_short Formulation optimization and synergistic effects of flocculation–solidification–vacuum preloading on sludge treatment
title_sort formulation optimization and synergistic effects of flocculation solidification vacuum preloading on sludge treatment
topic Sludge
Flocculation
Solidification
Vacuum preloading
Rice husk ash
url https://doi.org/10.1038/s41598-025-96752-7
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AT hongenwu formulationoptimizationandsynergisticeffectsofflocculationsolidificationvacuumpreloadingonsludgetreatment
AT xukunyang formulationoptimizationandsynergisticeffectsofflocculationsolidificationvacuumpreloadingonsludgetreatment
AT jianwenwei formulationoptimizationandsynergisticeffectsofflocculationsolidificationvacuumpreloadingonsludgetreatment
AT yunliangcui formulationoptimizationandsynergisticeffectsofflocculationsolidificationvacuumpreloadingonsludgetreatment