Analysis of particle size and fractal dimensions of suspensions contained in raw sewage, treated sewage and activated sludge

• Autorzy: Kuśnierz M. , Wiercik P.

Identyfikatory

DOI

10.1515/aep-2016-0031

Warianty tytułu

PL

Analiza wielkości cząstek oraz wymiarów fraktalnych zawiesin zawartych w ściekach surowych, oczyszczonych i osadzie czynnym

• Języki publikacji: EN

Abstrakty

EN

The analysis of particle size in suspensions carried out with use of the laser diffraction method enables us to obtain not only information about the size of particles, but also about their properties, shape and spatial structure, determined basing on fractal dimension. The fractal dimension permits the evaluation of the interior of aggregates, at the same time showing the degree of complexity of the matter. In literature, much attention is paid to the evaluation of the fractal dimension of flocs in activated sludge, in the aspect of control of single processes, i.e. sedimentation, dehydration, coagulation or flocculation. However, results of research concerning the size of particles and the structure of suspensions existing in raw and treated sewage are still lacking. The study presents optical fractal dimensions D3 and particle size distributions measured with use of laser granulometer in raw and treated sewage and activated sludge collected from six mechanical-biological wastewater treatment plants located in the Lower Silesian region. The obtained test results demonstrate that wastewater treatment plants that use both sequencing batch reactors and continuous flow reactors are more efficient at capturing suspension particles of a size up to 30 μm and are characterized by an increased removal of particles of a size ranging from 30 μm to 550 μm to the outflow. Additionally, in the case of samples of treated sewage and activated sludge collected at the same location, at short intervals, similar particle distributions were observed. As far as the analysis of fractal dimensions is concerned, particles contained in the raw sewage suspension were characterized by the lowest values of the fractal dimension (median equals 1.89), while the highest values occurred in particles of activated sludge (median equals 2.18). This proves that the spatial structure of suspension particles contained in raw sewage was similar to a linear structure, with a large amount of open spaces, while the structure of particles contained in the activated sludge suspension was significantly more complex in the spatial aspect.

PL

Analiza wielkości cząstek zawiesin metodą dyfrakcji laserowej pozwala uzyskać informacje nie tylko na temat wymiarów cząstek, ale także ich właściwości, kształtu oraz budowy przestrzennej, określanej na podstawie wartości wymiaru fraktalnego. Wymiar fraktalny pozwala na ocenę wnętrza agregatów, ukazując jednocześnie stopień złożoności obiektu. W literaturze dużo uwagi poświęca się ocenie wymiaru fraktalnego kłaczków osadu czynnego pod kątem kontroli procesów jednostkowych, tj.: sedymentacja, odwadnianie, koagulacja czy flokulacja, jednak wciąż brakuje wyników badań na temat wielkości cząstek i struktury zawiesin występujących w ściekach surowych i oczyszczonych. W artykule przedstawiono określone za pomocą granulometru laserowego optyczne wymiary fraktalne D3 i rozkłady wielkości cząstek w ściekach surowych, oczyszczonych i osadzie czynnym pobranych z sześciu mechaniczno-biologicznych oczyszczalni ścieków zlokalizowanych na terenie Dolnego Śląska. Uzyskane wyniki badań wskazują, iż oczyszczalnie ścieków pracujące zarówno w układzie zarówno reaktorów wsadowych jak i przepływowych powodują skuteczniejsze zatrzymywanie cząstek zawiesin o rozmiarach cząstek do 30μ m oraz podwyższone wynoszenie do odpływu cząstek w zakresie rozmiarów od 30 μm do 600 μm. Dodatkowo w przypadku próbek ścieków oczyszczonych i osadu czynnego pobieranych w tym samym miejscu i krótkich odstępach czasu zaobserwowano podobne rozkłady występowania cząstek. W przypadku analizy wymiarów fraktalnych najmniejszymi wartościami wymiaru fraktalnego (mediana równa 1,89) charakteryzowały się cząstki tworzące zawiesinę ścieków surowych, a najwyższymi cząstki osadu czynnego (mediana równa 2,2), co świadczy o tym, że budowa przestrzenna cząstek zawiesin zawartych w ściekach surowych była zbliżona do struktur liniowych z dużą ilością otwartych przestrzeni, a struktura cząstek tworzących zawiesinę osadu czynnego była znacznie bardziej rozbudowana przestrzennie.

Słowa kluczowe

EN

suspension; fractal dimension; laser granulometer; activated sludge; sewage; particle size distribution

PL

zawiesina; wymiar fraktalny; laser granulometrowy; osad czynny; ścieki; rozkład wielkości cząstek

• Wydawca: Institute of Environmental Engineering, Polish Academy of Sciences
• Czasopismo: Archives of Environmental Protection
• Rocznik: 2016
• Tom: Vol. 42, no. 3
• Strony: 67--76
• Opis fizyczny: Bibliogr. 43 poz., tab., wykr.

Twórcy

autor

Kuśnierz M.

• Wroclaw University of Environmental and Life Science, Poland, Institute of Environmental Engineering

autor

Wiercik P.

• Wroclaw University of Environmental and Life Science, Poland, Institute of Environmental Engineering

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Uwagi

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę.