Test and Analysis of Sludge Dewatering with a Vacuum Negative Pressure Load at the Bottom of Full Section

Qi, Yongzheng; Wang, Zongzhi; Jiang, Pengming; Guan, Yong Liang; Wang, Liyan; Mei, Ling; Zhou, Aizhao; Hou, Heying

doi:10.1155/2020/8875912

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…However, the method demands a high rock strata grade due to the large excavation section. Field experience [27,28] indicates that the full-section method is suitable for rock strata with grades I to III. Furthermore, the full-section method requires ample working space and relies on large machinery.…”

Section: Construction Methodsmentioning

confidence: 99%

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

Ren,

Zhou,

Jia

et al. 2023

Sustainability

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The construction of intersection tunnels in urban induces multiple stress redistribution in the surrounding rock, leading to engineering disasters such as instability in rock strata during excavation, disturbance of supporting structures in existing tunnels, and subsidence of ground adjacent buildings. Employing an appropriate construction method is crucial in circumventing excessive stress concentrations and large-scale rock strata subsidence, making it a key aspect of urban intersection tunnel engineering. In this paper, a numerical model for an urban intersection tunnel is developed based on an underground circular road project in a central business district. We conduct numerical simulations of the excavation processes using the full-section method, step method, and center cross diagram (CRD) method, respectively. The findings indicate that while different construction methods do not change the variation trends of surrounding rock stress and displacement, adjacent ground building deformation, and existing tunnel convergence, they affect the variation degrees. The maximum compressive and tensile stresses in the surrounding rock caused by the CRD method are the smallest, which are 3.56 MPa and 0.76 MPa, respectively. The maximum arch subsidence affected the amount, and horizontal convergence affected the amount of branch tunnel #1 caused by the CRD method are the smallest too, which respectively are 1.428 mm and 0.931 mm. The foundation subsidence and overall inclination of the ground building resulting from the three methods are identical. Then, we discuss the construction safety of the three methods and obtain the influence order on construction stability, which is as follows: full-section method > step method > CRD method. It is concluded that the CRD method is the most suitable for urban intersection tunnel engineering in terms of safety. This study could offer valuable insights for selecting construction methods in urban intersection tunnel engineering and provide a foundation for evaluating the safety and stability of tunnel construction.

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Section: Construction Methodsmentioning

confidence: 99%

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

Ren,

Zhou,

Jia

et al. 2023

Sustainability

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“…As shown in Table 1, China has introduced a series of regulations that impose specific requirements on the water content of sludge under various treatment and disposal conditions. In practical engineering, sludge dewatering without conditioning is very poor [5]. The more difficult moisture to remove in mechanical sludge dewatering is bound to water that cannot be removed by simple mechanical pressure [6].…”

Section: Introductionmentioning

confidence: 99%

Advances in Chemical Conditioning of Residual Activated Sludge in China

Liang

Wang

Sun

et al. 2023

Water

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Municipal sludge is characterized by high organic matter content, high viscosity, and fine particles, resulting in poor dewatering performance. This article analyzes the composition and properties of municipal sludge, examines the factors affecting the dewatering performance of sludge and the mechanisms corresponding to each influencing factor, and introduces chemical conditioning in detail. Chemical conditioning includes flocculation conditioning, oxidation conditioning, acid-base conditioning, and aggregate conditioning. The principles and applications of existing sludge conditioning technologies are systematically analyzed. By comparing the advantages and disadvantages of different technologies, it is pointed out that the key to developing sludge conditioning technology lies in developing a more appropriate combination of the sludge conditioning and dewatering process according to the sludge quality of different municipal wastewater treatment plants, taking into account their local environment, input costs, subsequent sludge disposal methods, and other factors, and further optimizing the sludge dewatering process by developing new efficient and environmentally friendly sludge conditioning agents.

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“…However, sludge has a complex composition, strong hydrophilicity, and a high water content, which makes sludge dewatering difficult [6][7][8]. Therefore, rapid sludge dewatering is a challenge in sludge treatment [9]. Sludge dewatering methods are mainly carried out by mechanical means such as belt type, plate frame type, and centrifugal type [10].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of sludge dewatering for single- and double-drainage conditions with a vacuum negative pressure load at the bottom

Zhang¹,

Zhang

et al. 2021

PLoS ONE

Self Cite

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The moisture content of municipal sludge is relatively high, which increases the cost of sludge transportation and treatment. To reduce the volume of the sludge, sludge dewatering is needed. This paper proposes the theory of sludge dewatering and facilitates efficient and economical technology of sludge dewatering. Sludge dewatering tests were carried out by using homemade rapid sludge dewatering devices. There were two groups of tests with single- and double-drainage conditions, and all test runs were loaded with a negative vacuum pressure at the bottom. During the experiments, the vacuum degree and the pore water pressure in the sludge were monitored in real time. After the experiments, the data were compared and analyzed. At the initial stage, the sludge dewatering extent and the sludge dewatering velocity for double-drainage conditions were much higher than those for single-drainage conditions. The vacuum occurring for single-drainage conditions lagged behind that for double-drainage conditions in the sludge. The value of vacuum degree for single-drainage conditions was lower than that for double-drainage conditions, and the vacuum attenuation for single-drainage conditions was considerable. The excess pore water pressure for double-drainage conditions dissipated faster than that for single-drainage conditions in the sludge. The pore water pressure for single-drainage conditions at the top and middle of the sludge layer first increased and then decreased in the early loading stage, resembling the Mandel effect. Overall, with a vacuum negative pressure load at the bottom, the sludge dewatering efficiency for double-drainage conditions was much higher than that for single-drainage conditions. This study provides an experimental and theoretical basis for engineering applications in the sludge treatment industry.

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Test and Analysis of Sludge Dewatering with a Vacuum Negative Pressure Load at the Bottom of Full Section

Cited by 7 publications

References 16 publications

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

The Influence of Construction Methods on the Stability of Tunnels and Ground Structures in the Construction of Urban Intersection Tunnels

Advances in Chemical Conditioning of Residual Activated Sludge in China

Experimental investigation of sludge dewatering for single- and double-drainage conditions with a vacuum negative pressure load at the bottom

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