| 疏浚淤泥化学絮凝−真空预压深度脱水效果评价 |
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| 引用本文： | 王东星,唐弈锴,伍林峰.疏浚淤泥化学絮凝−真空预压深度脱水效果评价[J].岩土力学,2020,41(12):3929-3938. |
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| 作者姓名： | 王东星 唐弈锴 伍林峰 |
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| 作者单位： | 1. 武汉大学 土木建筑工程学院 岩土与结构工程安全湖北省重点实验室，湖北 武汉 430072；
2. 武汉大学 水工岩石力学教育部重点实验室，湖北 武汉 430072 |
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| 基金项目： | 国家自然科学基金（No.51879202，No.52079098） |
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| 摘 要： | 为实现疏浚淤泥高效快速脱水减容，选取化学絮凝和真空预压相结合的脱水技术，利用自制真空预压抽滤装置对5种类型絮凝剂调理淤泥进行系列室内脱水试验，通过上清液高度、泥水分界面高度、沉降速率、底泥含水率等指标，综合评价疏浚淤泥沉降过程与深度脱水效果。结果表明：5种絮凝剂对应最优添加量分别为Ca(OH)2(1 500 mg/L)、PAFSI(200 mg/L)、PAC(200 mg/L)、HCA(50 mg/L)、APAM(500 mg/L)；与原始淤泥自然沉降过程相比（底泥高度17.14 cm、含水率96.8%），真空预压可实现絮凝调理淤泥脱水减容、底泥平均含水率降至53.5%，使底泥体积进一步压缩20.48%～36.99%；真空预压作用下，絮凝调理淤泥在50 min内达到沉降速率峰值，前120 min内淤泥絮凝效果明显、泥水分离程度占据主导；与原始淤泥真空预压对比，絮凝?真空预压大幅提升淤泥沉降速率、有效缩短峰值对应沉降时间，最优絮凝剂（APAM）底泥沉降速率峰值、淤泥总高度沉降速率峰值对应时间点缩短87.5%和83.33%，峰值速率分别增加3.56倍、5.18倍；添加适量絮凝剂能有效改善淤泥脱水性能，增大泥粒尺寸、防堵促排，加速疏浚淤泥沉降与泥水分离效率。化学絮凝?真空抽滤技术有利于实现疏浚淤泥减量化，显著缩短工期、加快施工进度、减少堆积占地，具有显著的工程应用价值。
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| 关 键 词： | 淤泥 絮凝剂 真空预压 泥水分离 沉降速率 底泥含水率 |
| 收稿时间： | 2020-04-04 |
| 修稿时间： | 2020-05-17 |
Evaluation on deep dewatering performance of dredged sludge treated by chemical flocculation-vacuum preloading |
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| WANG Dong-xing,TANG Yi-kai,WU Lin-feng.Evaluation on deep dewatering performance of dredged sludge treated by chemical flocculation-vacuum preloading[J].Rock and Soil Mechanics,2020,41(12):3929-3938. |
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| Authors: | WANG Dong-xing TANG Yi-kai WU Lin-feng |
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| Institution: | 1. Hubei Key Laboratory of Safety for Geotechnical and Structural Engineering, School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China; 2. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan, Hubei 430072, China |
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| Abstract: | The combined technology of chemical flocculation and vacuum preloading was proposed to achieve efficient and rapid dewatering of dredged sludge. Five representative flocculants were selected to facilitate the dewatering process using a self-made vacuum preloading filter device. The sedimentation and deep dewatering process of dredged sludge were comprehensively evaluated using a set of designed parameters, including supernatant height, mud-water interface height, settling rate and water content of bottom sludge. The experimental results indicate that the optimal amount of flocculants is 1 500 mg/L for Ca(OH)2, 200 mg/L for PAFSI, 200 mg/L for PAC, 50 mg/L for HCA and 500 mg/L for APAM, respectively. Compared with natural sedimentation process (17.14 cm in height and 96.8% of water content of bottom sludge), the effect of vacuum preloading can accelerate the consolidation and reduce effectively the sludge volume, i.e. the water content of bottom sludge decreases from 96.8% to 53.5% and the volume is compressed further by 20.48%?36.99%. The settling rate of sludge after vacuum preloading reaches its peak within 50 min, and the effect of flocculants associated with the mud-water separation degree plays a dominated role within 120 min. Compared with the original sludge subjected to vacuum preloading, the combination of flocculation-vacuum preloading significantly improves the settling rate of sludge and effectively shortens the required time to reach the peak settling rate. For the optimal flocculant (APAM), the time needed to reach the peak settling rate of bottom sludge and the peak settling rate calculated from total height of sludge are shortened by 87.5% and 83.33%, and the peak settling rate is increased by 3.56 and 5.18 times, respectively. The combined technology of chemical flocculation and vacuum preloading can effectively improve the dewatering performance of flocculated sludge, increase the particle
size to prevent blockage, accelerate drainage, promote the sludge sedimentation and improve the mud-water separation efficiency. The combined technique of flocculation-vacuum preloading, contributing to decrease sludge volume, shorten construction period, speed up construction progress and reduce the floor area, can play an important role if it is applied to engineering practice. |
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| Keywords: | sludge flocculants vacuum preloading mud-water separation settling rate water content of bottom sludge |
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