Coagulation is an important process in water and wastewater treatment, including  the removal of P-PO4. This process has not been fully examined and explained. It results from not only the complexity of this process, the quantity of factors influencing its process, but from the number of restrictions in the field of laboratory experiments. This paper presents a new method of researching complex processes of coagulation through a computer simulation. This computer program is based on a semi-empirical concept, inspired by observations of coagulation-flocculation-sedimentation of sewage containing, among others, P-PO4, carried out in both natural and model systems. In this study, a computer simulation was performed to examine the kinetics of latent coagulation, that can be the main determinant of coagulation efficiency. Several factors that influence the rate of latent coagulation were analyzed, including coagulant overdosing and underdosing, type of coagulant, initial concentration (load) of wastewater containing P-PO4, wastewater dispersion and initial velocity of sol and coagulant particles. The rate of latent coagulation decreased in response to both coagulant underdosing and overdosing. The time of latent coagulation was highly correlated with the degree of system dispersion. An increase in the size of sol and coagulant particles accelerated the rate of latent coagulation. The results of the study indicate that the costs associated with coagulant preheating are not compensated by the resulting increase in the rate of latent coagulation. A better response was observed by preheating or stirring sewage, in particular wastewater with a low load.

25.2.2020