Vízügyi Közlemények, 1969 (51. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

(69) tually with the treatment plants. Owing to the increasing wastes loading figures, treatment efficiencies higher than 95% will be required in the future and these are impossible to attain unless new and revolutionary changes are introduced in wastes treatment technology. Figures are available to indicate that from the total treatment costs of about 15 cents/cu.m, round 11 cents must be spent for raising the efficiency above 90%. Total treatment may still be regarded as a competitive alternative to desalination, or importation of water from great distances. Much remains to be done in Hungary in the field construction and automatic operation of treatment plants. In many instances it may become necessary to store conventionally (up to 85 — 90%) treated wastes for low-water periods in the recipient, or alternatively they must be disposed of underground. The policy of wastes disposal restricted to irrigation alone must be reconsidered and the economic feasibility of groundwater recharge and inverted wells must be studied in greater detail. The correct choice from among the potential solutions, i.e., the selection of the alternative offering maximum benefits, is in the final count impossible unless centralized pollution control measures are introduced and regional quality control is organised. The first, and perhaps most important step in this direction —accomplished largely by now in Hungary— consists of the classification of watercourses, and of the introduction of the socalled river criteria. The main principles to be observed when realizing detailed control within regional units have been laid down in the National Perspective Water Resources Plan of Hungary, as well as in comprehensive reports on water supply and sewerage. Part 3 is devoted to the methodological problems forming the scientific foundations for water quality control. Examples for these are the determination ol the wastes load which individual recipients are capable of handling, and departing therefrom, Uie specification of efficiencies for wastes treatment installations. The engineering-mathematical model presented is the most up-to-date, which has been introduced so far by few countries only for water management. The adoption of most advanced methods is desirable in this respect. Recipient watercourses (but also lakes and the oceans) may be regarded as natural treatment plants of a fixed capacity. The first and essential element in this treatment process is the diluting effect. Diffusion and dilution, as independent operational units, call for detailed studies, which should be started in the near future. Much work remains, however, to be done towards the better understanding and modelling of biochemical processes following dilution. The "oxigen bag" concept of Streeter and Phelps is considered, according to which there is a mutual interaction between the oxigen content of a stream and the decomposable (oxygen consuming) organic substances in it. The permissible load is limited by quality control, i.e., the specification of river criteria, also in view of other quality components, and it is for this reason that relationships were necessary between individual quality components and rate of streamflow. The permissible load in a particular component is characterized by the ratio of the "critical" value thus obtained and a limit value specified by empirical methods. The determination of the optimum treatment efficiency of treatment plants is demonstrated by the technique of linear programming. PRINCIPLES OF CONTEMPORARY SEWERAGE By S. Jakab (For the Hungarian text see pp. 321) Industrial development during the past 20 years resulted in appreciably higher rates of urbanization in Hungary. To counteract the undesirable expansion of the capital, Rudapest, industrial development is now concentrated by the government in rural districts, entailing the development of rural towns. At the present about 40% of the population dwells in towns, with more than half of them in such with over 100 000 inhabitants. In order to offer relief from housing shortage the building of 1.5 million new flats has been envisaged in a 15 year development plan. The great majority of these flats will be served by public utilities. ..