Study On The Fractal Properties Of Bridging Flocculated Aggregates For Yellow-River Mudsands

The settling of high-turbidity raw waters of Yellow-River mudsands on behalf of high concentration suspension liquids mainly belongs to phenomenon of "interference settling" or "zone settling".Conventional interference settling theories and formulae can't illustrate the effects of each of parameters on floe morphologies and structures during static and dynamic floeeulation processes and can't reflect real conditions of interference settling processes quantitatively and truly. Fractal mathematical theories are applied to combine static floe structures with its dynamic processes of growth and breakage etc. Furthermore, Fractal mathematical theories are used to study the settling regularities of high-turbidity raw waters of Yellow-River mudsands and floe fractal properties and growth models and the dynamic evolution processes of fractal structure by addition high molecular weight polymeric flocculants. So, we can describe and explain floeeulation processes exactly and quantitatively and predict floeeulation results, as well as we can control each of parameters effectively during floeeulation processes, so as to achieve optimum floeeulation efficiencies.In this dissertation, we mainly study aggregates fractal properties formed from bridging-flocculated processes of Yellow-River mudsands and canonic high molecular weight polymeric flocculants and the effects of hydrodynamic flow behavior on fractal properties; Under Shear-induced floeeulation conditions, bridging-flocculated mechanism of high molecular weight polymeric flocculants and dynamic evolution processes of fractal structure are discussed; Under the same floeeulation conditions, by bridging-flocculated settling experiment for kaolin particles and standard particulates by addition high molecular weight polymeric flocculants, fractal properties of bridging-flocculated aggregates of Yellow-River mudsands and adsorption properties and fractal behavior of high molecular weight polymeric flocculants are analyzed and discussed further.Mudsands aggregates structure formed from different flocculation conditions have self-similar structure widely. During the rapid and slow shear flocculation stages; growth mechanism of aggregates is Diffusion-Limited Cluster Aggregation (DLCA) model and Reaction-Limited Cluster Aggregation (RLCA) model mainly. Under different flocculation conditions, density-density correlation function on the basis of lattice method of box-counting dimension can be applied to calculate aggregates fractal dimension D2=1.4±0.1~1.9±0.1 and dry solid mass of aggregates as a function of equivalent sphere diameter in the three dimension space can be used to calculate fractal dimension D3=1.7+0.1 ~2.2 ± 0.1 by using settling experiment datum.Fractal properties bridging flocculation of mud sands aggregates are analyzed and discussed by application of settling and image analysis technologies and obtain the relation of fractal properties of aggregates which characterized by following parameters: floc size, floc voids, effective mass density, sedimentation rate, strength etc with fractal dimension D3.(1) floc size distributionThe shape of aggregates size distribution curve is similar to generalized normal distribution. The width of size distribution range can be indicated by parameter" fractal dimension D". When D>2, there is a fairly narrow spread sizes about the peak value. As fractal dimension is lowered, there is a shift towards a broader size distribution. The responding size distribution as a function of fractal dimension in terms of settling experimental datum can be expressed as following:During the whole flocculation processes, three size regions are immediately apparent in the data: ①10 - 150um, mainly with the "primary particles" and RLCA aggregates; ②150 - 300um, primarily with the DLCA aggregates and RLCA aggregates; and ③>300um, chiefly with the DLCA aggregates.(2) floe sedimentation rateswhen fractal dimension D is around critical value 2, there is a quite dramatic differences between aggregates sedimentation rates: when ZX2, the lower the fractal...