Department of Civil and Environmental Engineering, University of Delaware, 344A DuPont Hall, Newark, DE 19716, USA.
Department of Civil and Environmental Engineering, University of Delaware, 344A DuPont Hall, Newark, DE 19716, USA.
Sci Total Environ. 2018 Jun 15;627:713-722. doi: 10.1016/j.scitotenv.2018.01.209. Epub 2018 Feb 2.
A new sanitation technology has been proposed in which a laminated hydrophobic membrane contains and enhances drying of fecal sludge in a toilet, with particular focus on application to urban regions of low-income countries. The proposed technology uses a laminated hydrophobic membrane liner as an integral component of container-based sanitation systems. The focus of this study is to quantitatively evaluate the laminate's clogging after repeated use, which will affect replacement interval and might limit the laminate's application in container-based toilets. The membrane of the laminated hydrophobic membrane used in this process is hydrophobic and only allows vapor transport. Drying of water vapor using the laminated hydrophobic membrane occurs due to moderate temperature or humidity gradients, while other constituents such as aqueous dissolved solutes of fecal sludge are retained. Controlled laboratory experiments evaluated repeated use of a laminated hydrophobic membrane for fecal sludge drying, with mild brushing/rinsing of the laminate between each application. Drying occurred at a constant rate as long as the fecal sludge moisture content exceeded 11.6 (g/g), below which water activity <1. Over five drying cycles, at a significance level of α = 0.05 the dimensionless drying rate in the constant-rate period was not reduced. While scanning electron microscopy and energy dispersive X-ray analyses of used laminated hydrophobic membrane showed deposition of fecal sludge on the inner fabric of the laminate, particulate accumulation was never sufficient to alter the fecal sludge drying rate. Experiments with only water indicated that the fecal sludge increased the effective diffusion length through the laminate by 10-30%. These data demonstrate that clogging of the laminated hydrophobic membrane is minor over five cycles of fecal sludge drying with mild rinsing between cycles, indicating that use of the laminate may be feasible in many field applications.
一种新的卫生技术被提出，其中层压疏水性膜包含并增强厕所中粪便污泥的干燥，特别关注在低收入国家的城市地区的应用。所提出的技术使用层压疏水性膜衬里作为基于容器的卫生系统的整体组成部分。本研究的重点是定量评估层压疏水膜在重复使用后的堵塞情况，这将影响更换间隔，并且可能限制层压疏水膜在基于容器的厕所中的应用。该过程中使用的层压疏水性膜的膜是疏水性的，只允许蒸汽传输。由于温和的温度或湿度梯度，水蒸气在层压疏水性膜中的干燥发生，而粪便污泥的其他成分，如水性溶解溶质，则被保留。受控的实验室实验评估了重复使用层压疏水性膜进行粪便污泥干燥的情况，每次使用之间对层压疏水膜进行轻度刷洗/冲洗。只要粪便污泥的含水量超过 11.6（g/g），干燥就会以恒定速率发生，低于该值时水活度<1。在五个干燥循环中，在显著性水平α=0.05 下，恒定速率期内的无量纲干燥速率没有降低。尽管使用扫描电子显微镜和能量色散 X 射线分析对使用过的层压疏水性膜进行了分析，但在层压疏水膜的内部织物上发现了粪便污泥的沉积，但颗粒状物质的积累从未足以改变粪便污泥的干燥速率。仅使用水的实验表明，粪便污泥通过层压疏水膜增加了有效扩散长度 10-30%。这些数据表明，在五个粪便污泥干燥循环中，在每个循环之间进行轻度冲洗，层压疏水性膜的堵塞情况很小，表明在许多现场应用中使用该层压疏水膜可能是可行的。
