Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Marek Sokáč"

Quo vadis, urban drainage? DOI:10.15199/17.2018.3.4

  Impact of urbanization on the hydrological cycle extends beyond the limits of urban settlements and has minimally a regional impact affecting the fauna and fl ora in the adjacent basin. Hydrologic cycle of urban areas has a comprehensive character, where interconnections are at least as complex as in the natural hydrological cycle. Another, perhaps the most important factor in environmental protection and ecological equilibrium, is the pollution of the runoff and the recipient. The large and shock discharges, occurring in the urbanized catchments (Fig. 1) can usually be managed using temporary accumulation of water. In Slovak conditions this situation is solved mainly by the inclusion of combined sewer overfl ows (CSO) into the sewer system. The hydraulic function of the CSO’s consists in the simple hydraulic overfl ow of a part of the sewer fl ow (a mixture of untreated rain and sewage water) from the sewerage network to the recipient (watercourse), which obviously has signifi cant environmental negative impacts on aquatic water biocoenosis. Currently the tendency is to design and implement such concept of the city drainage, which would have its hydrological characteristics close to natural catchments (Fig. 1), [2]. In practice, this means the creation of such sewerage system of the city, which allows runoff reduction and regulation. The basic prerequisite for such strategy implementation is separate the collection and transport of these different wastewater types and to manage these various types of wastewater separately (especially rainwater and sanitary sewage water). The need of runoff reduction and regulation can be justifi ed by adopting the following considerations: the current increasing hydraulic load on the sewer network (an increase of impervious surfaces, urban expansion) causes that many sewers are overloaded or Keywords: urban drainage, sewer systems, sustainable development, reliability, urban catchment ru[...]

Status of sewerage and wastewater treatment in Slovakia

  Republika Słowacka leży w centralnym rejonie Europy Środkowej; jej liczba mieszkańców wynosi ok. 5.397.000 osób (2011). Całkowita liczba jednostkek osadniczych wynosi 2891, przy czym tylko 400 liczy ponad 2000 mieszkańców. Ogólna liczba mieszkańców w miastach liczących ponad 2000 osób wynosi 3.780.000, czyli około 70% ludności całego kraju. Reszta ludności zamieszkuje niewielkie miejscowości rozsiane po terytorium całej Słowacji. Warunki te, jak również wysoki udział ludności wiejskiej, stanowią utrudnienie w procesie budowy centralnych systemów zaopatrzenia w wodę i oczyszczania ścieków wodociągów i oczyszczalni ścieków, przewidzianych w traktacie akcesyjnym Słowacji do UE z roku 2004.1. Sewerage 1.1 Status In 2012 number of inhabitants supplied with drinking water from the public water sources reached the number of 4.707 mil., which represents 87 % of total inhabitants. Total length of drinking water pipelines was 29 088 km, it represents specific length of pipeline on connected inhabitant 6.18 m. In the Slovak Republic there are 2 349 municipalities with centralised public water supply system (81.3 % of the total number of municipalities). Total drinking water production was 302.5 mil m3 (89.25% from the ground water resources 270 mil m3 of drinking water were produced, what represent 89.25%, the rest of drinking water was produced from surface water resources). The water losses in the pipeline systems represented very high figures - 27.6 % from the total produced water in the Slovak Republic. Specific water consumption for households dramatically decreased from 195 l/cap.day (in 1990) to 80.8 l/cap.day (2011) [Ministry of Environment, 2013]. Development of public sewerage systems lags behind public water supplies. The connection percentage in the Slovak Republic is relatively low in comparison with developed countries of Western Europe. This dates back to the long-term neglected development of infrastructure construction[...]

Dispersion process in urban sewer networks under dry weather conditions DOI:10.15199/17.2016.4.7

  The paper describes determination of dispersion coeffi cients in sewer, which is from hydraulic point of view a prismatic and straight stream channel with relatively constant roughness of streambed. Field experiments were performed in a straight sewer sections and also in the part with sewer direction changes. Both were done under dry weather fl ow conditions, i.e. with relatively low pipe fi lling, discharges and velocities. Consequently, the dispersion coeffi cient in a sewer line with various direction changes was determined. At the end of the paper the observed effect of «dead zones» is described, which theoretically should not occur in conditions of our experiments (prismatic channel with no obstacles) and discuss its root cause.Introduction Sewer network is in term of the pollution transport a very complex system, in which physical, chemical and biological reactions and processes take place. All these processes and reactions impact the resulting pollution mass concentration and its time course. This paper is focused on two important physical processes - advection (mechanical transport of the pollutant by fl owing fl uid) and dispersion. Dispersion, from hydrodynamic point of view, is the spreading of mass from highly concentrated areas to less concentrated areas in fl owing fl uid. Mass in fl owing water is not transported only in the reach of streamline, but it is also gradually spreading to outside in consequence of velocity pulsations and mass concentration differences. Mass dispersion with advection is basic motion mechanics of particles, transported in water. Reductions of maximum concentrations are results of their effects. The main characteristics of dispersion are dispersion coeffi cients in relevant directions. Determination of these dispersion characteristics is the key task for solving problem of pollutant transport in streams and for modelling of water quality. The simplest description of the mass [...]

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