Zastosowanie flotacji ciśnieniowej do usprawniania koagulacji wody z Zalewu Zegrzyńskiego

Optimization of Lacustrine Water Treatment by Including Dissolved Air Flotation into the Treatment Train The technological studies reported in this paper were carried out at the pilot station of the Northern Water Treatment Plant in Wieliszew near Warsaw in the time span of 1996-1997. Water for municipal supply is taken in from the nearby lake Zalew Zegrzynski. The primary objective of the study was to investigate how the inclusion of dissolved air flotation into the treatment train might upgrade the efficiency of coagulation and, consequently, of the treatment process. Thus, coagulation ww carried out in a two-stage (1[0] and 11[0]) system involving dissolved air flotation and a pulsator, respectively. Another objective was to choose the most effective flocculant type and dose from the three items tested: Alz(S04)3, Fe2(S04)3, and mixed coagulant. The best treatment effects were obtained when use was made of a two-stage coagulation process with DAFin J°, at tlie following proportion of the optimum flocculant dose: 70% at I[0] and 30% at II[0]. The process designed via the above route provided favourable conditions for the operation of rapid sand filters and yielded water of good quality before adsorption on GAC beds.