Structure Compression in Cake Filtration
Structure Compression in Cake Filtration
复制标题
DOI：
10.1061/(asce)0733-9372(1997)123:4(345
复制
发表时间：
1997-04
影响因子：
2.2
通讯作者：
B. Sørensen;P. Sørensen
中科院分区：
文献类型：
--
作者：
B. Sørensen;P. Sørensen
针对滤饼过滤中的可压缩结构，研究了滤液流速、滤饼液体含量和滤饼结构压缩之间的关系。已经观察到，当压力高于临界值时，对于高度可压缩的滤饼结构，滤液流速几乎与过滤压力无关。在这项研究中，废物活性污泥的比阻进行了调查和临界过滤，在此之上的滤液流速是独立的压力，被发现是0.02巴，一个值远低于在脱水过程中使用。滤饼内任何点的局部值的比电阻和液体含量对于表征滤饼过滤中可压缩结构的行为是重要的。然而，很难在滤饼结构中进行局部测量。因此，局部性质通常通过校准滤饼过滤的数学模型从总体污泥过滤参数确定。然而，这些模型需要了解结构应力、流动阻力和液体含量之间的局部函数关系。这一要求是模型校准中的一个问题。在这项研究中开发的方法避免了局部关系的要求，但允许局部结构应力，比电阻，和液体含量从整体测量之间的关系的确定。利用该关系式，确定了垃圾活性污泥的局部比阻和孔隙比。废物活性污泥的关系表明，对数的局部比电阻是成比例的对数结构应力。局部孔隙比随结构应力的增加而迅速减小。这对应于极端可压缩的行为。
The relationship between filtrate flow rate, cake liquid content, and cake structure compression is investigated for compressible structures in cake filtration. It has been observed that when the pressure is above a critical value, the filtrate flow rate is nearly independent of filtration pressure for highly compressible cake structures. In this study the specific resistance of waste-activated sludge is investigated and the critical filtration, above which filtrate flow rate is independent of pressure, is found to be 0.02 bar, a value well below that used in dewatering processes. local values of any point within the cake of specific resistance and liquid content are important to characterize the behavior of compressible structures in cake filtration. It is, however, difficult to make local measurements in the cake structure. Therefore, the local properties are often determined from overall sludge filtration parameters by calibration of mathematical models for cake filtration. These models require, however, knowledge of local functional relationships between structure stress, flow resistance, and liquid content. This requirement is a problem in the calibration of the models. The methods developed in this study avoid the requirement of local relationships but allow the determination of relationships between local structure stress, specific resistance, and liquid content from overall measurements. The values of local specific resistance and void ratio are determined for waste-activated sludge using the relationships. The relationships determined for waste-activated sludge show the logarithmic local specific resistance to be proportional to the logarithmic structure stress. The local void ratio is shown to decrease rapidly for increasing structure stress. This corresponds to an extremely compressible behavior.