Hidrológiai Közlöny 1973 (53. évfolyam)
12. szám - Bulkai János–Licskó István–Szépkuti Lajosné: Hidrometeorológiai viszonyok hatása a lebegő anyagok Zéta-potenciáljára
564 Hidrológiai Közlöny 1973. 12. sz. Bulkai L., Licskó I., Szépkuti L.-né: Hidrometeorológiai viszonyok intervallumba tartozó napi empirikus eloszlásokat. Az illeszkedésvizsgálatot elvégezve azt kaptuk, hogy az illeszkedés feltétele az esetek 80%-ában teljesült. A további 20% — kevés kivételtől eltekintve — tartományhatáron van és igen jól közelíthető a másik tartományt jellemző eloszlásfüggvénnyel. Az illeszkedés jellemző valószínűségi százalékai természetesen rosszabbak, ha azt az egyes napokhoz tartozó elméleti eloszlásfüggvényekkel hasonlítjuk össze. Az illeszkedés enyhe romlásáért viszont azt kapjuk cserébe, hogy az egész éves adatsort három eloszlásfüggvénnyel egyértelműen tudjuk jellemezni. Megállapíthatjuk tehát, hogy az általunk vizsgált három hidrometeorológiai állapotban a Zétapotenciál eloszlását jól jellemezhetjük a három paraméteres r(x 0, X, k) eloszlással. F(X): l k m X J (*-« o! *-i eA( <-V d t (4) *>0) A 4. táblázat és a (4) egyenlet felhasználásával meghatározható, hogy adott hidrometeorológiai állapotban mi a valószínűsége annak, hogy a Duna vizében adott helyen a kolloid szemcsék Zétapotenciálja egy adott értéknél kisebb lesz. Látható tehát, hogy — legalábbis a mérsékelt égöv alatt -— a hidrometeorológiai viszonyokkal kapcsolatban áll a felszíni vizek lebegőanyagának elektrosztatikus töltése. Ennek a törvényszerűségnek pedig bizonyos mértékben hatással kell lennie a víztisztítás folyamatára, hiszen a klasszikus technológiai ágazatokban a koaguláció éppen ezeknek a töltéssel rendelkező lebegőanyagoknak eltávolítását biztosítja. IRODALOM [1] Bernhardt H.: Das Zeta-Potenciál als Hilfsmittel der Flockiingstechnik. Vom Wasser 1965. 12] Szigyártó Z.: Hidrológiai események valószínűsége. Vízügyi Közlemények. 1966 4. 453—480. The effect of hydrometeorologieal conditions on the zeta-potential of suspended solids by Bulkai, L., Licskó, I., Szépkúti, TJ. (mrs.) Concerning the methods applied for water treatment it is of considerable interest to know whether the physical quantity which is accessible to measurement and is characteristic for the surface properties of the colloidal particles to be removed is unaffected by the hydrometeorological conditions, or follows the variations thereof. Measurements were carried out for one year (June, 1970 to July, 1971) on practically every working day, in order to record even the minute changes in hydrometeorological characteristics. For these measurements a Kiddick-type ZETA METER was used. The colloidal particles encountered in Danube water were found to carry a negative charge. At the same time, almost every particle within a sample had a different zeta potential. For this reason it is impossible to describe a particular hydrometeorologieal situation positively and unambiguously by a single zeta potential value. An attempt was subsequently made to describe the electrostatic charges of the colloidal particles present in Danube water pertaining to a particular hydrometeorologieal situation by the distribution of the zeta-poten tial values observed. The observation data were processed with the help of a computer. The one-year long observation record revealed no correlation between the suspeittled solids content and zeta potential, further between conductivity and zeta potential in Danube water. On the other hand, the data plotted in Fig. 3 indicated a relationship of limited validity to exist between the number of algae counted in unit volume anil the value of the zeta potential. At an increasing alga count the zeta potential tended to zero, whereas decreasing counts were accompanied by increasing zeta potential values. A relationship of similarly limited, but more general validity was found to exist between river stage and the zeta potential. At falling stages the daily average values decreased considerably relative to those of the preceding days. The strong shift towards higher zeta potential values at rising stages was, however, much more characteristic (Fig. 3). The increase in daily average zeta potential values at rising stages is attributed to the higher concentration of particles of mineral origin. Seasonal changes are always accompanied by variations in water temperature. Thus somewhat boldly, but not without justification certain temperature intervals may be regarded to characterize specific seasons. Of course, no exact limits must be expected, or observed. After careful considerations three temperature ranges have been selected, with the following limit values: cold water 0 to 4 °C; water of intermediate temperature 4 to 15 °C; warm water above 15 °C temperature. In warm water measurements have shown the daily average zeta potential values to range from 14 to 15 mV. In water of intermediate temperatures (primarily in autumn) the values between — 13.0 and —-14.0 mV are most common, although in spring the lower limit of the range is shifted towards zero. In cold surface waters the daily average zeta potential values were scattered in the interval between — 15.0 and — 17.0 mV. The temperature-zeta potential pairs of values observed in autumn were used in correlation computations. The correlation coefficient obtained was 0.80, while in spring the corresponding values was no more than 0.69. Consequently the temperature-zeta potential relation is a closer one in autumn than in spring. The temperature-zeta potential relation is not a functional relation, in that a change in temperature does not always entail a change in the zeta potential. The daily average zeta potential is influenced by the combination of hydrometeorologieal factors, such as alga count, stage, water temperature mentioned before. The positive determination of relationships between the individual factors and the zeta potential is made difficult thereby and underlines even more the trend character of the existing relations. The zeta potential values observed on the individual days were found with a few exceptions to form a sample consisiting of independent elements from the same distribution. This offered the possibility for determining the distribution function of the zeta potential values observed, regarding these as random variables. The empirical distribution function was found to fit the gamma distribution and as a limit case thereof, the normal distribution. In 58.5% the cases the gamma distribution was used for approximation. The tests of fit revealed that the theoretical distribution functions applied describe well the distribution function of the observed zeta potential values as random variables. Hydrometeorologieal situations differing substantially from each other were found to alter considerably the distribution of zeta potential values (Fig. 4). The empirical distributions characterizing practically identical hydrometeorologieal situations satisfied the criterion of uniformity (Fig. 5, Table 3). On this grounds it was assumed that identical hydrometeorologieal situations can be described by a single distribution function. The theoretical distribution functions characterizing diverse hydrometeorologieal situations were determined (Fig. 6,
