Hidrológiai Közlöny 1971 (51. évfolyam)

1. szám - Kolin László: A vízminőség szerepe és változásai tározókban

56 Hidrológiai Közlöny 1971. 1. sz. Special Conference Number, Szebellédy, L. the prototvpe, and that for this purpose the type of flow in the model must be the same as that in the actual basin. Reviewing the present situation of research it appears safe to conclude that all results of fundamental research and theory are already available, which permit the determination of the optimum hydraulic solution before actual designing and construction of a new basin is started. The papers submitted to the conference reflect these modern trends of research. 4. Problems releated to the design of storage basins Depending on their location and function within the distribution system, and according to their hydraulic role, the storage basins may be classified into two groups: — flow-through systems, — pressure basins (elevated tanks). Basins of the first type are in generál the last structures in water works and treatment plants, where the purified water is collected and the reserves stored in them, to ensure the uniform rate of water production and treatment, without influence from fluctuations of consumption. These basins are usuallv the structures in which the last phase of treatment, namelv disinfection is performed and thus more or less successfull attempts are always made to ensure adequate circulation in them. The time of residence in the basin is at the same time the period during which the disinfecting agent is effective. In flow-through storage basins the inlet: outiét ratios may be as follows: filling (period of low consumption): Q

m > Q

ou

t balanced condition: . Qí,

l = Q

ou

t emptying (peak period) Q

i

n > Q

ou

t Pressure basins (or elevated tanks) are located at elevated points of the distribution system, or occasionally at the and opposite to the producing plánt. Their function is to store water at periods of low consumption and to release it again at times Fig. 1. Flow conditions in a rectangular storage basin of 2X500 cu. m capacity of peak-demand. Accordingly the direction of flow in these basins is always the same. The correct hydraulic design of these basins presents the most difficult problems and much remains to be cleared in this respect. In pressure basins the ratio of inflow- and out'flow may be as follows: filling Q

i

n 0 Q

ou

t = 0 stagnation Q

i

n = 0 Q

ou

t = 0 consumption Q

i

n = 0 Q

o

ut *+* 0 4.1. Storage basins in Hungary During the past 25 years municipal water supply underwent extensive development in Hungary and necessitated the construction of a large number of basins for storing drinking water. Several standard and individual designs have been developed, but even individual designs served repeatedly as the basis of construction. It must be admitted,— in generál —that in spite of the adequate theoretical understanding of the related problems, the storage basins constructed here so far fail to meet the contemporarv requirements for hydraulic conditions and conservation of water quality. Water is introduced and withdrawn invariably point—like, through single pipes and consequently the resulting flow conditions are essentially two-dimensional. This has the consequence, that even if the flow pattern is satisfactory in the pláne of inflow—and outflow, there is no guarantee whatsoever, that this applies over the entire depth in the basin. Storage basins commonlv used in Hungárián practice are illustrated in Figs. 1 to 5.