THE INFLUENCE OF THE VELOCITY GRADIENT ON MORFOLOGICAL PROPERTIES OF AGGREGATES

Abstract eng:
This paper summarises the preliminary results concerning an influence of the agitation conditions on the aggregation processes. The properties of formed aggregates affecting the efficiency of separation processes are studied as well. The results show that the applied velocity gradient G, the period of its action T and the distribution of velocity field in an agitated volume of water significantly influence the number of aggregates, their size and shape. Smaller and denser aggregates of a homogeneous size and more resistant to breakage are formed under a higher velocity gradient. Introduction The process of aggregation of destabilised particles resulting in formation of separable aggregates belongs to the basic technological processes of water treatment. Conditions of aggregation and magnitude of adhesive and tangential forces interacting between aggregating particles in contact affect resulting characteristics of formed aggregates, their shape, size and internal structure. In complex, they determine physical characteristics of aggregates, substantially affecting the efficiency of the separation processes commonly used in water treatment technology. In the past, a great number of studies were dedicated to investigate the influence of the physical factors on the kinetics of the aggregation process and a number of relationships were derived to describe it. With the practical application aimed at controlling the performance of the works and its design, these relationships are applicable in a very limited extent only. Very few studies enabling the determination of conditions of agitation and its influence on the properties of aggregates, which influence the efficiency of the separation processes and the properties of produced sludge, were published (Hudson, 1965

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