Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(10) THE GROWING SIGNIFICANCE OF GROUNDWATER RECHARGING By Dr. Öllős, G. (For the Hungarian text see pp. 3) Based on experience gained during UN-WHO-sponsored study tour WesternEuropean practice in groundwater recharging is described. Besides increasing groundwater resources artificial recharging will play in the future an increasingly important role in the improvement of water quality. The explanation therefore lies in the fact that raw-waters become gradually more polluted by an increasing number of pollutants, so that conventional treatment technologies based upon the familiar chemical processes and rapid filtering are in many cases unable to cope with them. The removal of taste- and odour substances from water are among the causes which will make recharging in many locations inevitable, provided suitable hydrogeological conditions are available. Slow filtration with the attendant biological purifying effect, is the complex process resulting in water most reminiscent of groundwater if water is given enough residence time in the soil. Applicability is limited by the pollutant —absorbing capacity of the soil, i.e., its self-purification potential. This should be remembered in the future when planning the operation of groundwater recharging installations, or the treatment technology for full treatment, including pre- and after-treatment as well. In the course of groundwater recharging water may also become polluted owing to the geological properties of the soil. A detailed analysis of these mainly chemical and biological processes is presented. It is concluded that more extensive and systematical research is needed in this field. Potential applications and the limits of the hydraulic approach are considered, followed by an analysis of factors (temperature, algae, biochemical oxidation, changes in pH and CO„, nitrogen compounds, iron and manganese, detergents, radioactive substances, effects due to the mixing of waters) affecting the changes in water quality during recharging. Indications of the necessity, practical applications, potential methods and alternatives of pretreatment before recharging, or after treatment are pointed out. Relying on the relevant literature (e.g. 1, 2, 5, 9, 10, 13 and 16) the main trends in water treatment associated with recharging are reviewed. Typical cases, installations and designs for groundwater recharging have also been compiled. Examples are given for installations whose objectives are enhancement of supply or the improvement of quality, and operating with different technologies such as pondage, basin, ditch, inverted well and gallery types. In this connexion brief descriptions are given on the following plants: Basel Waterworks, groundwater recharging plant at Hard (Figs. 15 — 18), the Jugfernheide Waterworks in West-Berlin ( Figs. 19 — 21 ), the flow diagram of a typical plant of the water treatment and groundwater recharging project along the Rhine ( Fig. 22), treatment and groundwater recharging at the Frankfurt Waterworks (Figs. 23 — 25), the Haltern Waterworks (Figs. 26 — 28), the Dortmund Waterworks (Figs. 30 — 34), the HorstAltendorf Waterworks (Fig. 35), groundwater recharge at Lake Tegel in WestBerlin (Figs. 36—37), the groundwater supply area Donauried (Figs. 38 — 39) and the Kettwig treatment plant (Fig. 40). DEVELOPMENT OF THE SZINVA-SPRING By Dr. Léczjalvy, S. (For the Hungarian text see pp. 41) Szinva-spring emerges from karstic rock of the Eastern Bükk Range in the northern part of Hungary. It is one of the karstic springs with the greatest yield, the annual average of which is 21,000 lit/min. The spring was developed in 1964 for supplying water to the town of Miskolc, the largest industrial center in NorthHungary. Research, exploration and designing work associated with development construction and experience gained thereby arc described.