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1
Content available Real values of local resistance coefficients during water flow through a pipe aerator with filling
Kalenik Marek, Chalecki Marek, Wichowski Piotr, Kiczko Adam, Chmielowski Krzysztof, Świętochowska Martyna, Gwoździej-Mazur Joanna
Journal of Water and Land Development
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2023
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no. 59
174--182
EN
The paper presents the results of studies on local resistance coefficients (ζ). The study used pipe aerators with filling made according to the Polish patent PL235924. The hydraulic investigations were performed in real working conditions of a water treatment plant in a testing rig built in the Scientific and Research Water Station of the Warsaw University of Life Sciences (SGGW). The investigation encompassed two plastic pipe aerators of an internal diameter 101.6 and 147.6 mm with steel Białecki rings of 12 and 25 mm in diameter. Measurements of pressure difference (Δp) in the investigated aerators were performed at volumetric water flows (Q) selected from the range 2-20 m3∙h-1 with the interval 2 m3∙s-1. The values of ζ were determined according to the PN-EN 1267:2012 standard. The investigation showed that the ζ depends both on an internal diameter of the plastic pipe aerator and the diameter of Białecki steel rings. The values of ζ increase with a decrease of the internal diameter of the pipe aerator and a decrease of the ring diameter.
2
Content available Efficiency of wastewater purification in medium sand with a lightweight expanded clay aggregate assisting layer
Kalenik Marek, Wichowski Piotr, Chalecki Marek, Kiczko Adam
Journal of Water and Land Development
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2023
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no. 57
30--38
EN
The objective of this experimental study was to examine whether an assisting layer of lightweight expanded clay aggregate (LECA) of the granulation 1-4 mm, introduced into a subsoil, is able to improve an efficiency of removal of total nitrogen and total phosphorus from domestic wastewater. In the investigations, an assisting 0.10 and 0.20 m thick LECA layer was applied. It has been observed that the effectiveness of removal of total suspended solids (TSS), total nitrogen and total phosphorus from wastewater as well as the level of biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) is in accordance with the Polish standards on wastewater disposal into grounds and surface water. The performed experiments showed that the effectiveness of raw wastewater purification for the medium sand soil bed with the 0.20 m thick assisting LECA layer is higher than for the 0.10 m thick assisting layer. In the medium sand soil bed with the 0.20 m thick assisting LECA layer, the removal efficiency regarding total nitrogen increased by 20.6%, total phosphorus by 5.2%, ammonium nitrogen by 8.8% and TSS by 5.3%, and reduction efficiency regarding BOD5 increased by 1.7% and COD by 2.3% with relation to the 0.10 m thick assisting LECA layer (all percentages - in average). The results of the experiment showed that the LECA with the granulation 1-4 mm can be used to assist in removal of total nitrogen and total phosphorus from wastewater with application of infiltration drainage.
3
Content available Investigations on the effectiveness of wastewater purification in medium sand with assisting opoka rock layer
Kalenik Marek, Chalecki Marek
Environment Protection Engineering
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2021
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Vol. 47, nr 1
53--65
EN
The objective of the undertaken investigations was to examine in laboratory conditions whether an introduction of an assisting opoka rock layer with the granulation of 1–6 mm into the ground improves the removal efficiency of nitrogen and phosphorus compounds from domestic sewage. The performed investigations concerned the layer supporting the removal efficiency of domestic sewage in a home sewage treatment plant under infiltration drainage. The model investigations of wastewater purification were carried out in a medium sand bed with an assisting, 0.10 and 0.20 m thick opoka rock layer. The effectiveness of wastewater purification related to basic qualitative indicators (total suspended solids – TSS, BOD5, COD, total nitrogen, total phosphorus) was in line with the Polish standards on sewage disposal into grounds and surface water. The medium sand soil bed with the 0.20 m thick assisting opoka rock layer showed higher effectiveness of wastewater purification than that 0.10 m thick. The application of the 0.20 m thick opoka rock layer increased the removal efficiency regarding TSS by 6.2%, total nitrogen by 20.4%, ammonium nitrogen by 8.3% and total phosphorus by 2.9%, and removal efficiency regarding BOD5 by 1.2% and COD by 1.9% with relation to the 0.10 m thick assisting layer (all percentages − in average). The results confirm that the natural opoka rock with the granulation of 1–6 mm can be used to assist in the removal of nitrogen and phosphorus compounds from wastewater with the application of infiltration drainage.
4
Content available Stability and vibrations of micro-nonhomogeneous plate band resting on elastic subsoil
Chalecki Marek, Jemielita Grzegorz
Archives of Civil Engineering
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2021
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Vol. 67, nr 1
403--424
EN
The paper presents a procedure of calculation of natural frequencies and critical buckling forces of a micro-nonhomogeneous plate band resting on nonhomogeneous elastic subsoil and having any given boundary conditions. The band consists of N parts - cells - called elements, having a constant width l = L/N. Each band element consists of three parts - subelements with variable widths. The two of these subelements are matrix, the third - inclusion placed symmetrically relative to the matrix. Each band element is built of two isotropic materials. The matrix and inclusion bands have the stiffness and mass per area unit as well as they rest on the subsoil. The model has been derived with use of the classical displacement method. The stiffness matrix of any band element and then the band stiffness matrix have been built. An appropriate computer program has been written to calculate natural frequencies and critical buckling forces. A number of tests have been performed to check the working of the program and several calculative examples has been presented in the paper.
PL
W pracy przedstawiono sposób obliczania częstości drgań własnych i wyznaczania wartości sił krytycznych mikroniejednorodnego pasma płytowego o dowolnych warunkach brzegowych, spoczywającego na niejednorodnym podłożu sprężystym. Pasmo składa się z N części - komórek, zwanych elementami, o stałej szerokości l = L/N. Każdy element pasmowy składa się z trzech części - subelementów o zmiennych szerokościach. Dwie z nich są osnową, trzecia zaś wtrąceniem symetrycznie położonym względem osnowy. Każdy element pasmowy składa się z dwóch izotropowych materiałów. Pasma osnowy i wtrącenia mają pewne sztywności i masy na jednostkę powierzchni oraz spoczywają na podłożu o pewnej sztywności. Do wyznaczenia częstości drgań własnych i wartości krytycznych zastosowano metodę przemieszczeń. Zbudowano macierz sztywności dowolnego elementu pasmowego, a następnie macierz sztywności pasma. Ułożono odpowiedni program na wyznaczenie częstości drgań własnych i sił krytycznych ze względu na wyboczenie. Wykonano szereg testów sprawdzających działanie programu i podano szereg przykładów obliczeniowych.
5
Content available Model Investigations of Flow Rate and Efficiency of Air Lift Pump with PM 50 Mixer and Circumferential Mixer
Kalenik Marek, Chalecki Marek
Rocznik Ochrona Środowiska
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2020
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Tom 22, cz. 1
456--474
EN
The paper presents the analysis of results of investigations concerning an influence of applied constructive solutions on hydraulic operating conditions of a water-pumping air lift pump. The scope of the investigations encompassed the determination of flow rate and efficiency characteristics of an air lift pump having the discharge pipe with the internal diameter d = 0.04 m. The PM 50 mixer with a perforated rubber membrane, available on the market, as well as a mixer of own design, called circumferential mixer, were tested (the name origins from the fact that the mixer has the shape of a ring which encloses the discharge pipe on its whole circumference). The investigations were performed for three air-water mix delivery heads H: 0.40, 0.80, 1.20 m, for the specified pressure pipe submergence length h = 0.80 m. It has been stated that for both types of the applied mixers the water flow rate Qw increased along with the increase of the air flow rate Qa, reaching maximum, then decreased. However, in both of the applied mixers, the water flow rate Qw permanently decreased as the air-water mix delivery head H increased. The air lift pump achieved higher water flow rate Qw if the circumferential mixer was applied instead of that with perforated rubber membrane. It has been proved that for both of the applied types of mixers the air flow rate Qa in the air lift pump cannot be lower during water pumping than 5.0 m3·h-1 and should not exceed 15.0 m3·h-1 in case of the circumferential mixer and 16.0 m3·h-1 for the perforated rubber membrane mixer. The efficiency h of the tested air lift pump for both of the applied types of mixers decreased when the air-water mix delivery head H increased. The higher efficiency h, however, was obtained for the air lift pump with the circumferential mixer than for the perforated rubber membrane mixer.
PL
W artykule przedstawiono analizę wyników badań, dotyczących wpływu stosowanych rozwiązań konstrukcyjnych mieszaczy na hydrauliczne warunki pracy powietrznego podnośnika do tłoczenia wody. Zakres badań obejmował wyznaczenie charakterystyk wydajności i sprawności pracy powietrznego podnośnika o średnicy wewnętrznej rurociągu tłocznego d = 0,04 m. Do badań wykorzystano mieszacz dostępny na rynku typu PM 50 z perforowaną gumową membraną i mieszacz własnej konstrukcji, który nazwano mieszaczem obwodowym (nazwa pochodzi stąd, że ma on kształt pierścienia, który obejmuje rurociąg tłoczny na całym jego obwodzie). Badania wykonano dla trzech wysokości podnoszenia mieszaniny wody i powietrza H: 0,40, 0,80, 1,20 m, przy stałej długość zanurzenia rurociągu tłocznego h = 0,80 m. Stwierdzono, że dla obu zastosowanych typów mieszaczy natężenie przepływu wody Qw rosło wraz ze wzrostem natężenia przepływu powietrza Qa osiągając maksimum, a następnie malało. Natomiast w obu zastosowanych typach mieszaczy wraz ze wzrostem wysokości podnoszenia mieszaniny wody i powietrza H, natężenie przepływu wody Qw tylko malało. Większą wydajność natężenia przepływu wody Qw powietrzny podnośnik uzyskał z mieszaczem obwodowym niż z mieszaczem z perforowaną gumową membraną. Wykazano, że dla obu zastosowanych typów mieszaczy natężenie przepływu powietrza Qa w powietrznym podnośniku podczas tłoczenia wody nie może być mniejsze niż 5,0 m3·h-1 i nie powinno przekraczać dla mieszacza obwodowego 15,0 m3·h-1,, a dla mieszacza z perforowaną gumową membraną 16,0 m3·h-1. Sprawność pracy h badanego powietrznego podnośnika dla obu zastosowanych mieszaczy malała wraz ze wzrostem wysokości podnoszenia mieszaniny wody i powietrza H. Natomiast dla powietrznego podnośnika z mieszaczem obwodowym uzyskano większą sprawność pracy h, niż dla powietrznego podnośnika z mieszaczem z perforowaną gumową membraną.
6
Content available First natural frequency of multi-segment floor joists with variable cross section
Chalecki Marek, Jaworski Jacek, Szlachetka Olga
Przegląd Naukowy Inżynieria i Kształtowanie Środowiska
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2019
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Vol. 28, No. 4
526--538
EN
The Rayleigh’s method can be used to determine the first natural frequency of beams with variable cross-section. The authors analyse multi-segment simply supported beams, symmetrical with respect to their midpoint, having a constant width and variable height. The beams consist generally of five segments. It has been assumed that the neutral bar axis deflected during vibrations has a shape of a beam deflected by a static uniform load. The calculations were made in Mathematica environment and their results are very close to those obtained with FEM.
7
Content available Investigations on the effectiveness of wastewater purification in medium sand with assisting clinoptilolite layer
Kalenik Marek, Chalecki Marek
Environment Protection Engineering
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2019
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Vol. 45, nr 2
117--126
EN
Model investigations of wastewater purification were carried out in a medium sand bed with an assisting natural clinoptilolite layer 0.10 or 0.25 m thick. The effectiveness of wastewater purification related to basic qualitative parameters was in accordance with the Polish standards on sewage disposal into grounds and surface water. Medium sand soil bed with the assisting natural clinoptilolite layer 0.25 m thick showed on average the removal efficiency regarding TSS higher by 3.3%, total nitrogen by 29.3%, total phosphorus by 25.9%, reduction efficiency regarding BOD5 by 1.1% and COD by 15.9% than that with the thinner clinoptilolite layer. The investigations confirmed that natural clinoptilolite with the granulation 1-5 mm can be used to enhance the removal of nitrogen and phosphorus compounds from wastewater with the application of infiltration drainage. However, very good effect of the TSS removal from the wastewater in the investigated soil beds can lead to their fast clogging under the infiltration drainage. Septic tanks should be designed in such a way that they retain as much TSS as possible, e.g., multi-chamber tanks instead of one-chamber ones.
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