A Test Method for Measuring Floc Size of Slurry

摘要

Large amounts of waste slurry are produced in geotechnical engineering construction that need to be dewatered. Flocculation is typically introduced to improve the dewatering efficiency, and the floc size is a significant parameter for dewatering. Floc size distribution can be measured off-line using a laser particle analyzer. However, it has been observed that mechanical agitation during measurement can cause breakage of the flocs, potentially leading to measurement errors. The current study presents a method for measuring floc size more precisely. An Erlenmeyer flask placed on a platform shaker is used as the dispersion unit instead of the conventional dispersion unit provided by the laser particle analyzer. Flocs are mixed by hydraulic agitation provided by the platform shaker. A peristaltic pump is used to pump the suspension from the Erlenmeyer flask to the laser particle analyzer. Additionally, this article evaluates the accuracy of the off-line in situ floc size measurement method with the laser particle analyzer. A photography and image analysis, which can quantify the floc size distribution, is used to compare the results obtained from the hydraulic agitation method and the in situ method. The experimental results reveal that the hydraulic agitation method is a reliable method for measuring floc size distribution with small aggregate breakage (10 %). The in situ method, in contrast, generates errors with severe breakage and inhomogeneous aggregate breakage (10 %-55 %).