Hidrológiai Közlöny 1971 (51. évfolyam)

1. szám - Varró István: Felszíni vizek tisztításának korszerű módszerei és anyagai

Special Conference Number, Szebellédy, L. Hidrológiai Közlöny 1971. 1. sz. 45 mes either contain a metál (metalloproteide enzyme), or need for their activation Ca, Mg, or Mn. Another method of treating surface water is deseribed by A. Gagnaux. This is referred to as the MD method, developed by the French Compagnie des Eaux et la l'Ozone. The M D process, indicating micelhzation and demicellization, consists of three stages, namelv 1. micro-straining, 2. micelhzation and demicellization, and 3. rapid filtration with subsequent disinfection, where required. Micro-straining is but a process of mechanical pretreatment, for which micro-drum filters are used. Hereafter the verv fine suspended matter remaining in the filtrate must be removed. Flocculants are added in an amount only to form hydrosol-gels, which can be filtered immediately (rapid-coagulation filtration). The formation of hydro-gels is greatly promoted by ozone treatment. Its effect consists of destroying the organic macro-molecular compounds which lend colour and turbidity to water. E. g. the double bond of polymerised humic acid is destroyed, together with the polysaccharides, which are transformed into acids and combine with the alkali earth metals present in water to insoluble compounds. Depending on the quality of water the following phenomena may occur upon contact with ozone: a) complete discolouring of water without the occurrence of subsequent turbidity. Any turbidity originally present in water is removed. b) Turbidity occurs, which can be traced back to the formation of colloidal micellae (micelhzation). c) Flocculation of colloids with the formation of micro-flocs (demicellization). Rapid filtration through sand filters is followeel by disinfection, e. g. with chlorine. The process is claimed to be effective alsó for the treament of waters containing iron and manganese. Ozone may well be regarded essential for the treatment of surface waters. It is used before, during and after treatment, but in somé instances twice, namely during and after treatment. A drawback of ozone is the high cost of operating ozone generators. Mass transfer processes and reaction kinetics of ozone generators and reactors are analysed in the paper by I. Horváth. The transport equations deseribing ozone-uptake and the decomposition of ozone are written in the form of differential equations, the solution of which vields the kinetic equations of mass transfer. Relying on the theoretical considerations applying to static and flow-through svstems a method is presented for determining the major kinetic parameters and design eriteria. The valitidv of the relationships derived is demonstrated by a detailed series of experimentál results, quoting alsó the published observation data of F. Sulzer. The data used for the demonstration apply to a) twice distilled water, b) tap water and c) groundwater. The main steps of computing the kinetic Constanta are illustrated by graphs and a numerical example. Theoretical values were found to be in fair agreement with observation data, demonstrating the validity of the mathematical models and that the parameters are actually representative of the mass transfer and kinetic processes in ozone treatment reactors, so that their use as design eriteria is indeed permissible. The use of ozone for the treatment of water is gaining popularity in Hungary, but has not vet reached the stage which would be desirable. Individual phases of development and the present situation are deseribed in detail in the relevant paper by L. Kolin. Certain advances have been achieved in utilizing the oxidizing effect of ozone and this method of treatment is used not only as a means of disinfection, but primarily for removing unpleasant odour and taste from water. Favourable experiences have been gained in oxidizing poorly removable manganese. For the ozone treatment experiments conducted with water from the Eastern Main Canal, the equipment manufactured by VILATI was alsó used. The rated capacity thereof is 60 g 0

3/hour and it is capable of operating under pressure. The experiments and checking measurements were supervised by the Research Institute for Water Resources Development. The results obtained with this water of inferior quality showed ozone to be highly effective in removing objectionable taste- and odour substances and have a perfect disinfecting effect. Economical methods for introducing ozone into water are considered subsequently. The relevant experiments have been performed by VITUKI with cooperation of the experts of the Consulting Enterprise for Civil Engineering. Experiments performed with the aim of determining the favourable introduction of theozone-air mixture into water haverevealed that 1. an excessive number of nozzles on the distribution pipea brings no advantages, since a certain resistance is necessary for the satisfactory distribution of the ozone-air mixture, 2. cylindrical nozzles, or such with a mildlv tapering verticai surface result in adverse bubble formation, 3. nozzles of very small diameters should not be used. The experimentál results are very interesting. The solutions applied in the fixed installation are favourable and thus economical. The results deseribed should be utilized for ozone treatment technologies in new plants. Besides chlorine and its compounds effective disinfection is possible alsó with ozone. In this respect ozone is 10 to 20 times as effective as chlorine, but there are certain difficulties in investment and operation to be solved. As already mentioned, ozone has been introduced in the technological process, but its use as the exclusive means of disinfection is still sporadic. Ozone as a means of disinfection is analysed in the paper by K. Marschall. The development of ozone generation, the fields of application are reviewed, pointing out in this connection that being a.