Vízügyi Közlemények, 1987 (69. évfolyam)

1. füzet - Licskó István-Zotter Katalin: Savas csapadék befolyásolta felszíni vizek tisztítási technológiájának módosítása

Savas csapadék befolyásolta felszíni vizek... 57 Коагуляционные-флоккуляционные опыты, проведенные с различными поверхностными водами, показали, что под влиянием добавлением алюминиевого сульфата, необходимого для очистки, понижение pH значительно больше, чем в случае кислых осадков (рис. 2 и 3). Особенно значительное понижение pH и щелочности наблюдалось в воде водохранилища Чоррэт, которая характеризуется низким буфферным объемом. Авторами были проведены эксперименты с целью достижения уменьшения степени понижения pH и щелочности. В отдельных экспериментах учитывалось и влияние кислых осадков и определялось количество гидрокарбоната натрия или карбоната натрия, которое необходимо для компенсации этих неблагоприятных воздействий (рис. 4 и 5). Кислые атмосферные осадки, в первую очередь, в результате снеготаяния, влияют на понижение pH воды водохранилища Чоррэт. Окисление неблагоприятно сказывается и на технологии очистки воды и приводит к ухудшению качества обработанной воды питьевого назначения. Путем изменения технологии очистки воды, включением и регулирования pH, достигается и неблагоприятное действие кислых осадков. * * * Modification of the treatment technology of surface waters influenced by acidic precipitation by DR. I. LICSKO, professor of chemistry and physics and DR. K. ZOTTER (Miss), professor of biology and chemistry The unfavourable effect of acidic precipitation on the quality of water was practically unknown ten-twenty years ago. Due to the well-known changes in the 70's, however, the spread of pollutants causing acidification-with no regard to state borderlines-has become a global problem. In Hungary, the damages in soil and vegetation are presently in some regions the hallmarks of an accelerating process in acidification of the environment. Because of the geological and hydrogeological characteristics of Hungary, one cannot discover permanent acidification, at the time being, in available surface and subsurface water resources. The damaging effect of acid depasition on existing surface and subsurface water resources can be observed at sites where the acid-adsorbing capacities of the mother-rock, soil and vegetation were minimum, and the buffer-capacity of the given water sample (hydrogen-carbonate-ion concentration, in other words: alkalinity) was substantially lower than the national average value. It was shown that the water supply reservoirs established in the region of the Mátra Mountains (e.g. the reservoir of Csórrét) have had a much lower alkalinity than the national average (Fig. 1., Table I). The low buffer-capacity of the reservoir at Csórrét and the characteristic quality parameters of the precipitation measurements in Hungary (Tables II and III) justified the execution of an investigation on the effect of acid depasition on the technology of water treatment. According to observations made in the period of January-March, 1985 it has become clear that the concentration of heavy metals in the snow cover (in the catchment of the reservoir) was not negligible any more (Table IV). The authors revealed that in the different depths of the reservoir the pH-values of the water decreased substantially after snowmelt (Table VI). The change of pH-values due to acid dosage in the different surface waters was also investigated (Table V). Later, calculations were performed to find out the expected pH-reducing capacity of a certain acidic load originating from snowmelt. These calculations ended in similar results than actual measurements. During experiments on coagulation-flocculation in different surface waters it could be stated that a much larger change (decrease) of the pH-value could be detected after addition of the necessary amount of a certain purifier (usually aluminum-sulphate) than it could have been detected by an acid depasition (Figs. 2 and 3). Especially, in a reservoir with a small buffer-capacity (like the reservoir of Csórrét) extra decreases in pH and alkalinity could be observed. Experiments were conducted to reduce the rate of decrease in pH and alkalinity. In this effort