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Pore-scale model and dewatering performance of municipal sludge by ultrahigh pressurized electro-dewatering with constant voltage gradient
- Source :
- Water research. 189
- Publication Year :
- 2020
-
Abstract
- The disposal of huge municipal sludge with high moisture content has led to numerous energy consumption and brought extensive concerns in the world. In this paper, three dewatering modes, ultrahigh-pressure mechanical dewatering mode (UMDW), pressurized electro-dewatering (PEDW) with constant voltage mode (U-PEDW) and constant voltage gradient mode (G-PEDW) were performed on a self-designed pressurized electro-dewatering apparatus for municipal sludge. The pore structures and moisture distributions were detected by low-field nuclear magnetic resonance technology. Meanwhile, the moisture distributions and quantitative bound strength were analyzed by the thermogravimetric differential scanning calorimetry test. Moreover, a pore-scale electro-osmosis model was accordingly developed based on the fractal characteristics of pore size distribution. Finally, the effect of dewatering modes and operating parameters on moisture content and energy consumption were examined in detail. The results indicate that the pore-scale electro-osmosis model show good consistency with experimental data. The electric field can drive the middle-layers-water to overcome the capillary pressure, and make G-PEDW removing more water than UMDW. The moisture content of dewatered municipal sludge by G-PEDW and U-PEDW reaches to 28.41% and 27.33%, respectively. Furthermore, the energy consumption of G-PEDW is 189.62Wh/kg.H2O, it is much lower than that of U-PEDW. Therefore, the G-PEDW mode with low moisture content and less energy consumption indicates best dewatering performance compared with UMDW and U-PEDW modes. The present work is helpful to understand the dewatering mechanisms of G-PEDW and provides useful guidelines for G-PEDW dewatering technology.
- Subjects :
- Work (thermodynamics)
Capillary pressure
Environmental Engineering
Materials science
0208 environmental biotechnology
02 engineering and technology
010501 environmental sciences
Wastewater
01 natural sciences
Waste Disposal, Fluid
Differential scanning calorimetry
Electricity
Electric field
Waste Management and Disposal
Water content
0105 earth and related environmental sciences
Water Science and Technology
Civil and Structural Engineering
Moisture
Petroleum engineering
Sewage
Ecological Modeling
Water
Energy consumption
Pollution
Dewatering
020801 environmental engineering
Subjects
Details
- ISSN :
- 18792448
- Volume :
- 189
- Database :
- OpenAIRE
- Journal :
- Water research
- Accession number :
- edsair.doi.dedup.....87608e1f8a6bfe805464ce75be288e34