Hidrológiai Közlöny 1971 (51. évfolyam)
1. szám - Dr. Öllős Géza: A kutak vízhozamát befolyásoló tényezők
20 Hidrológiai Közlöny 1971. 1. sz. Special Conference Number, Szebellédy, L. — part of the iron dissolved in the water, is precipitated due to oxidation on the filter pipe surface and in the gravel pack, as a result of which the resistance of the well — as a structure — increases. Thus it is no wonder that vield diminished (Kg. 4), — when producing aggressive water, it is therefore expedient to endeavour a continuous operation. 2.3. Incrustation Incrustation is understood as the clogging process clue to compounds containing iron and manganese. The process is enhanced alsó by corrosion. The paper by L. Marton deals with this problem. Fig. 6. illustrates the developmcnt of the well disclosed near Miskolc, the exploration shaaft and the sampling spots. The filter pipe was cut at 5,4 ni depth and withdrawn. Prior to siting the well the originál iron content of the water was 1.50—1.65 mg/l. At the time of developing the well, the iron content was 0.59 — 1.55 mg/l. It thus seems that the iron content in the water was diminished somewhat by the well. The most probable explanation of this phenomenon is that in the vicinity of the well, the iron (and usually alsó the manganese) precipitates in the form of a residue. Table 1 contains the mean values of somé components affecting water quality, as pertaining to the levels in Fig. 4. From these values it was concluded that of the components the oxides of trivalent metals play the principal role, they being present in about 80 to 90%. Any reduction of the well vield due to clogging is caused first of all by the iron compounds alone, or in combination with these compounds. G. Szolnoky called attention to a highly important process in the course of iron bacteria breeding: amorphous ferric hvdroxide residue precipitated on the surface of tubiform or helical fibrous iron bacteria. The fibrous structure which developed from the iron precipitate as a result of the biochemical process, was covered more and more by the amorphus precipitate. This led to the conclusion that the microbiological activity or presence of iron bacteria may have a major role in accumulating the amorphous iron precipitate in wells. On the basis of their investigations, S. Karácsonyi and L. Marton alsó concluded the following: — metallic sieve cloths should be avoided as far as possible, due to their susceptibility to clogging, 0fl/p] 500 1000 m 1 1500 "V * 1 1959 \J 1966 ^ 1 1962 Fig. 7. Yield data of the (clogging) well No. tí 3 at the Szekszárd Waterworks — autotroph and heterotroph fibrous iron bacteria may both cause the clogging of wells. Therefore, organic and inorganic nutrients (pollutants) should, if possible, kept awav from the well-zone. In view of the increasing pollution of subsurface waters, this problem will most probably gain in significance. — the reddish antennaelike zones developing around the wells from iron precipitate, encircle alsó the artificial gravel pack. This fact indicates that the residue did not form in the soil layer before the well was constructed but later only, during operation. Of the relevant investigations attention should be called to the publications of E. Bieske., U. Hasselbarth, D. Lüdemann, and K. Hünerberg. Concerning the decrease of yield due to clogging, a good example is given by S. Karácsonyi (Fig. 7) showing the yield data of well No. B 3 at the Szekszárd Water Works. The prolification of iron and manganese bacteria around the well was believed to be caused by turbulent seepage. The limit beyond which an intensive biological process is likely to occur was expressed in terms of the Re*,, value. This interpretation was not well founded. The introduction of the Re-number — as a parameter — however, may be justified even today, if the nutrient concentration supplied by water is taken into consideration as the other parameter. The increase in seepage velocity results in the supply of more nutrients in the immediate vicinity of wells. In the area around the well, the bacteria Table ]. Mean value expressed in grams and weight percent of components contained in 1 kg soil sample Location (according to Fig. 4.) Fe 20 3 AI 2O 3 CaO + MgO CaC0 3 Loss of ignition Dissolved Location (according to Fig. 4.) (gram, %] [gram, %] [gram, %] [gram, %] [gram] A — level B — level C —level D — level 8.65 55.2 8.82 53.8 10.11 59.2 6.55 52.8 4.98 31.8 5.31 32.4 5.00 29.1 3.58 29.2 1.85 11.8 2.11 12.85 1.65 9.60 2.09 16.9 0 0 0 0 0.20 1.22 0.17 1.06 0.36 2.10 0.14 1.13 15.68 16.41 17.12 12.36
