The computer program ZB2 was used to study simulated coagulation, flocculation, and sedimentation. The effect of the initial velocity of soil particles on the values of reaction‐rate constants was investigated. In this respect, the results obtained with the program ZB2 corresponded to the theory and realities of coagulation carried out under practical conditions. The effect of coagulant excess/deficiency on the formation of the first floc and on the rate of coagulation of 50% of a soil was also estimated. An increase in simulated coagulant excess caused a decrease in the simulated rate of soil coagulation. In this respect, the results obtained with the program ZB2 did not correspond to the realities of coagulation carried out under practical conditions. An attempt was made to explain this inconsistency referring to the coagulation‐flocculation theory. The simulation program ZB2 may provide a basis for developing “local” programs simulating coagulation‐flocculation, which can be successfully applied at wastewater treatment plants.

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This paper discusses the results of laboratory analyses of the coagulation and flocculation of model wastewater. The investigated wastewater was susceptible to treatment by chemical coagulation. The effectiveness of two commercial coagulants, PAC produced at the DEMPOL-ECO Chemical Plant and PIX manufactured by KEMIPOL, was compared. A mathematical model relying on a second-degree polynomial was used to describe and analyze experimental data. In each case, the parabola minimum point was a precisely determined coagulant dose, regarded as the optimal dose. The application of a coagulant dose higher than the optimal dose reduced the effectiveness of wastewater treatment by coagulation. A detailed analysis of turbidity, suspended solids, total phosphorus and pollutant removal measured by the COD test revealed that PAC was a more effective and a more efficient coagulant than PIX. The risk of coagulant overdosing was greater with the use of PAC than PIX.

This work reports on a computer-simulated investigation of the coagulation rate for a system comprising spherical sol and coagulant particles. The discussed experiment positively verified the functioning of the simulated coagulation system, where the aggregation process proceeds in line with the particle-cluster model as a rapid and perikinetic coagulation process that satisfies the Smoluchowski equation. The rate of the simulated coagulation process satisfies kinetic equations for both first-order and second-order reactions. Selected concepts and models of the coagulation theory have been also verified.