Hidrológiai Közlöny 1971 (51. évfolyam)

1. szám - Dr. Öllős Géza: A 2. Vízminőségi és Víztechnológiai Kongresszus összefoglalása

Hidrológiai Közlöny 1971. 1. sz. 59 CONCLUSIONS of the 2nd Conference on Water Quality and Technology By I)r. ÖLLÖS, GÉZA Candidate of Technical Sciences, Associate Professor, President of the Sub-Coniittee on Water Supply and Sewerage, Committee on Scientific Water Management, Hungárián Academy of Sciences The most striking conelusion arrived when reviewing the proeeedings of the Conference is that water supply as an activitv is becoming inereasingly complex and involved. In earlier decades the problems which the experts of water supply encountered were of a more simple character and those arising in connection with water quality and treatment technology were easier to solve. The quality of natural resources has deteriorated by now everv where more or less and the liope for reversing this process is verv slight. No judgment on quality can be given and no problem in treatment technology can be solved, unless considered carefully by a group of experts representing different branches of science. Whereas mechanical (settling, rapid filtration) and chemical (clarification, disinfection) treatment processes were formerly successful and in generál adequate for treating a water of given quality, in recent times increasing attention must be paid to purification proceses of biological character (slow filtration) and to combined, several-stage methods (e.g. combinations of ozone treatment and slow filtration, or the application of active carbon, in generál the use of somé adsorbing material, the application of oxidizing-flocculating agents in one, or several stages). This is understandable, since water supply experts carry increasing responsibilities and consumers are increasingly conscious of the quality of water. With the advance of sciences and the growth of information on water, the demands concerning the quality of drinking water become more pressing. Under the combination of these factors the experts in water supply are prompted to cooperate more closelv with experts in public health and to increasingly allow for the sanitarv requirements in the design and operation of water supply svstems. The inevitable development outlined above has necessarily determined the objectives for the present Conference, namelv the introduction of a complex approach into the consideration of current problems associated with water quality and treatment technology, the solution of which is essential for the future. The Conference is believed to have succeeded in offering opportunity to representatives of all branches of science for outlining special considerations and requirements. From the papers submitted to the Conference and the discussions conducted 011 them during the sessions many positive conclusions can be arrived at. The main results, 011 which agreement seems to have been reached can be summarized as follows: 1. It becanie repeatedlv apparent during the sessions that increasing attention should be devoted to the studv of processes. This follows from the very nature of this field, as well as from the actual wealtli and standard of information available. Whereas the "pure processes" approach was predominant in the pást, operating experience and observations in plants and in the field have prompted laudable efforts towards the realistic surveving of processes and the more thorough understanding of their details. Whereas the earlier approach lead from principally theoretical knowledge through designing to operation, there is now a welcome influence observable, which operating experience exerts on designing and theoretical investigation. Whereas the role of hydraulic research was predominant in the past, the necessity for including other related processes is increasingly appreciated, without, however, neglecting hydraulics as the starting basis. Somé of these attendant processes could be listed as follows: various related micro-phenomena, — effects due to the role of surface forces, variations in nutrient household, — variations in, and distribution of water quality components (e.g. dissolved oxygen) in both time and space, — the uniformity, or non-uniformitv of distributions, and — oxidation and reducing processes. A trulv objective approach to water treatment cannot be expected without the careful and detailed analysis of these and similar phenomena. 2. It has become apparent that in many instances a new approach to the hydraulics involved is alsó necessary. Somé processes, as e.g. water production by bank filtration, or by wells, cases of groundwater recharging, cannot be described adequately by the conventional approach of hydraulics. A növel type of applied hydraulics must be developed for the designer. In this type of hydraulics allowance must be made alsó for the factors affecting—adversely of beneficially —the yield and quality of water produced and appearing in combination with the actual, e.g. filtration process. Applied hydraulics should be extended increasingly alsó to processes taking place e.g. in the treatment structures. Extensive research of almost basic character is necessary, before e.g. the theory of settling can be simplified to designing level, the retention time reflecting the volumetric design principle in the dimensioning of clarifiers can be assumed reliablv, the inertia forces at solid boundaries or in curvüinear flow, the effects of secondary currents, the non-uniform distribution of pollutants, etc: can be allowed for adequately.