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Zastosowanie programu SWMM do oceny funkcjonowania oczyszczalni wód deszczowych

Górski J., Szeląg B., Bąk Ł.

Woda-Środowisko-Obszary Wiejskie

2016

T. 16, z. 2

17--35

Prognoza jakości i ilości ścieków deszczowych oraz osadów ściekowych jest bardzo złożona ze względu na stochastyczny charakter zjawisk opadowych oraz procesów gromadzenia i zmywania zanieczyszczeń deponowanych na powierzchni zlewni. Ma to szczególnie duże znaczenie w projektowaniu ciągów technologicznych oczyszczalni wód deszczowych (OWD), gdzie przyjęcie błędnych założeń na etapie obliczeń może doprowadzić do nieprawidłowego funkcjonowania poszczególnych obiektów i urządzeń. Przedstawiona w artykule wstępna ocena funkcjonowania oczyszczalni wód deszczowych przy ul. Witosa w Kielcach, do której dopływają ścieki głównie z terenu pod zabudową jedno- i wielorodzinną, stanowi pierwszy etap badań, mających na celu stworzenie modelu matematycznego analizowanego fragmentu sieci kanalizacyjnej. Model numeryczny oczyszczalni wód deszczowych (OWD) wykonano w programie SWMM (ang. Storm Water Management Model) na podstawie dokumentacji projektowej obiektu oraz wizji terenowej, natomiast model hydrodynamiczny zlewni wraz z siecią kanalizacji deszczowej – na podstawie map topograficznych i zasadniczych. Do obliczeń średniego jednostkowego natężenia deszczu (q) wykorzystano 33 zdarzenia opadowe zarejestrowane w latach 2010–2011, podczas których czas trwania deszczu i wysokość warstwy opadu zmieniały się odpowiednio w zakresach td = 12–1244 min oraz P = 1,8–44,6 mm. Przeprowadzone symulacje działania OWD wykazały, że gdy średnie jednostkowe natężenie deszczu przyjmowało wartości poniżej 10 dm3∙(ha∙s)-1, stopień redukcji zawiesin ogólnych (η) w osadniku zmieniał się w granicach 0,78–0,98, a gdy q = 10–75 dm-1∙(ha∙s), to η = 0,69–0,88. Wykonane w pracy obliczenia mają charakter wyłącznie szacunkowy, ponieważ model nie został skalibrowany na podstawie rzeczywistych wartości natężenia przepływu ścieków deszczowych oraz stężenia zawiesin ogólnych.

Due to the stochastic character of precipitation phenomena combined with an accumulation of pollutants in the catchment area and their wash-off, the prediction of stormwater quantity and quality, its sediments is very complex. It is especially important when designing the stormwater treatment plant’s (STP) stages of technological lines, because there can be massive calculation errors at selection and functions of particular objects and equipment. The preliminary evaluation, of stormwater treatment plant in Witosa St., Kielce shown in the above article, where stormwater runs off mainly from housing estates of single and multi-family houses, is the first stage of researches concerning preparation of the mathematical model of analysed part of a sewer system. The numerical model STP was made by SWMM software and was based on the working plans of the object and field studies, whereas the hydrodynamic modelling with stormwater drainage system were made according to topographic and basics maps. 33 rainfall events were used to measure the amount of average rainfall intensity. They were registered between 2010 and 2011. During that time the rainfall duration and depth of precipitation changed as follows: td = 12–1244 min and P = 1.8– 44.6 mm. The simulations done by STP shown that in case of average rainfall intensity below 10 dm3∙(ha∙s)-1 the reduction of TSS (η) in a catch basin would change into 0,78–0,98, for q = 10–75 dm3∙(ha∙s)-1, the result was η = 0,69–0,88. The calculations carried out at work are only approximate, because the model was not calibrated on the basis of the actual value of the stormwater flow, the rainfall amount and total suspended solids concentrations.

Pokrywa śnieżna jako ośrodek depozycji zanieczyszczeń

Ociepa E., Mrowiec M., Deska I., Okoniewska E.

Rocznik Ochrona Środowiska

2015

Tom 17, cz. 1

560--575

The paper presents the results of snow contamination collected from roadsides and parks of Czestochowa in these areas which are out of the impact of a transport. The study was conducted within 2009–2011, in which 120 samples were tested in general. In snowmelt and rain waters that are brought to the sewer or land there are the following pollutants such as: suspended solids, hydrocarbons, heavy metals, biogenic compounds, and even bacteriological contamination. The scope of the research included: pH, total suspended solids, COD and heavy metals in waste water coming into the sewer. On the basis of the survey and analysis of the literature data it is possible to admit the high variation in pollutant concentrations in snow cover, mainly related to the place of sampling. It should also be noted that the other factors, such as: the length of snow cover, the outside temperature, the duration of test runs, the direction of the winds, in the case of the particular type of a substance thawing roads, have affected the results of measurements substantially as evidenced by their differentiation to the point for further measurements. The samples of snow from the sides of roads and parking areas have been characterized by a high content of suspended solids falling within the broad range from 165 to 1325 mg/dm3, COD values ranged from 89.0 to 825.0 mg O2/dm3. The pH of the snow stood at the level of 4.75–6.50. The analysis of the results has shown that the vast majority of the samples has been characterized by a natural or light acidity. The pH value was associated with a place and time of sampling. Most of the snow samples, collected from roadsides with heavy traffic and parking spaces, pointed to their acidic or slightly acidic character. The average content of heavy metals: Cd, Pb, Zn, Cu and Ni within the snow was generally low, which could be due to the fact that the tests were performed within metals concentration in water after the filtration of a suspension. It should be pointed out, however, that the snow from these areas that are exposed to the direct impact of transport, contained more metals for several times, compared with the periphery of busy roads or parking lots. On this basis it can be concluded that the main source of pollution of snow cover was, as analyzed, the catchment traffic, much less air pollution from the other sources. Therefore, the concentration of pollutants in snow cover areas directly adjacent to roads and parking spaces, due to the high concentration of pollutions, ought to be monitored. It should be paid attention to the need to standardize the procedures within sampling the snow.