1
|
Xiao K, Lv Y, Yu W, Yang J. Visualization of water transfer channel in sludge dewatering conditioned with skeleton builders by X-ray micro-computed tomography. CHEMOSPHERE 2024; 355:141818. [PMID: 38548085 DOI: 10.1016/j.chemosphere.2024.141818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 03/05/2024] [Accepted: 03/25/2024] [Indexed: 04/18/2024]
Abstract
Skeleton builders were normally deemed to improve the high porosity and newly-generated permeability of sludge cakes by building water transfer channel during high pressure filtration, thus enhancing sludge dewaterability. However, currently a direct visualization proof of water transfer channel was still lacking. This study provided the direct proof for visualizing water transfer channel in dewatered sludge cakes conditioned with a typical skeleton builder (i.e., phosphogypsum (PG)) by X-ray micro-computed tomography (micro-CT) for the first time. After the addition of PG, the pixel value and image luminance increased significantly, indicating the presence of high density substances from both two-dimensional (2D) cross section and three-dimensional (3D) reconstruction CT images. Moreover, the CT numbers showed strong and negative correlations with specific resistance to filtration (SRF) (R = - 0.99, p < 0.05), capillary suction time (CST) (regression coefficient (R) = - 0.87, probability (p) < 0.05), and water content of the dewatered sludge cake (R = - 0.99, p < 0.05), respectively. These results indicated that the X-ray micro-CT could be a potential technique for analyzing the water distribution in sludge samples conditioned with skeleton builders.
Collapse
Affiliation(s)
- Keke Xiao
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Environmental Science and Engineering Program, Guangdong Technion-Israel Institute of Technology, 241 Daxue Road, Shantou, Guangdong, 515063, China
| | - Yang Lv
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of the People's Republic of China, 8 Jiangwangmiao Street, Nanjing, Jiang Su, 210042, China
| | - Wenbo Yu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Provincial Engineering Laboratory of Solid Waste Treatment, Disposal and Recycling, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; Hubei Water Quality Safety and Water Pollution Control Engineering Center, 1037 Luoyu Road, Wuhan, Hubei, 430074, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China.
| |
Collapse
|
2
|
Wang Z, Wang Q, Lai J, Liu D, Hu A, Xu L, Chen Y. Numerical Simulation of Heat and Mass Transfer in Sludge Low-Temperature Drying Process. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1682. [PMID: 36421537 PMCID: PMC9689238 DOI: 10.3390/e24111682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/10/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Based on the sludge mass transfer flux model, this paper conducts a simulation study on the drying characteristics of sludge under low-temperature environment and compares it with the previous experimental results. It is found that when the sludge moisture content is low, the change of its drying curve is basically consistent with the experimental results, but there is a large error when the sludge moisture content is 0.4-0.6. In order to better simulate sludge drying characteristics, a model of cracking and shrinkage coefficients based on sludge moisture content is proposed, and the effective diffusion coefficient and mass transfer coefficient are modified. The maximum error between simulation and experiment is reduced to 23.78%. Based on this model, the sludge drying mechanism was studied. It was found that heat transfer and diffusion played a major role in the initial stage of sludge drying, and diffusion played a major role in sludge drying 30 min later.
Collapse
Affiliation(s)
- Zhenyu Wang
- School of Environment and Resources, Southwest University of Science and Technology, Mianyang 621010, China
| | - Qiang Wang
- School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China
| | - Ju Lai
- School of Economics and Management, Southwest University of Science and Technology, Mianyang 621010, China
| | - Dong Liu
- School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China
| | - Anjie Hu
- School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China
| | - Lin Xu
- School of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyang 621010, China
| | - Yongcan Chen
- School of Environment and Resources, Southwest University of Science and Technology, Mianyang 621010, China
| |
Collapse
|