过滤(数学)
相变
化学
污水污泥
污水
相(物质)
材料科学
化学工程
色谱法
环境工程
热力学
环境科学
有机化学
统计
数学
工程类
物理
作者
Boran Wu,Donghai Yang,Ningrui Yu,Hewei Li,Wei Ye,Xiaohu Dai
出处
期刊:Water Research
[Elsevier]
日期:2023-10-20
卷期号:247: 120765-120765
被引量:6
标识
DOI:10.1016/j.watres.2023.120765
摘要
The sustainable application of thermal sludge drying process is limited by the high energy consumption due to the phase-change latent heat of moisture. This study proposed that the ultrahigh pressure filtration could realize the non-phase-change sludge drying. The lowest water content of 28.12 wt.% was realized by the filtration pressure of 21 MPa for the excess sludge with polyaluminium chloride as the conditioning agent. With the stepwise increase of filtration pressure employed (5-21 MPa), the diameter of solid pores was gradually narrowed to the same order of magnitude with the thickness of vicinal water film (i.e., 1-10 nm). As a result, the capillary water was transformed into the vicinal water, and the solid-water interface interaction played more crucial roles in water occurrence states. However, Hagen-Poiseuille equation was introduced to estimate the pore water outflow based on the pore wall hydrophilicity and the external filtration pressure, which implied that there can be always a sufficiently large driving force to maintain the water outflow rate no matter how the pore diameter is small and the sidewall is hydrophilic. Typically, the fitting results of excess sludge (R2=0.985, p-value<0.01) indicated that the pressure gradient of 2.11 × 109 Pa/m was required to maintain the pore water flow rate of 1.38 × 10−15 m3/s with the median pore diameter of 5.33 × 10−7 m. All these findings broke through the conventional cognition that only thermal drying process can decrease the sludge water content below 60 wt.%, and facilitated energy saving of sludge dewatering process through non-phase-change separation, i.e., ultrahigh pressure filtration.
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